III REGION

* i
--.
III REGION
WASHINGTON
.
pane
Field work and acknowledgments ..........................................
Early history and previous work ...........................................
Geography ...............................................................
Location ..............................................................
Nomenclature .........................................................
W e t .................................................................
Geheral character ..................................................
Uplande ............;:...;-,..., : .. ................................
.
..
a-
Lowland? ................................-.:'+-.. i . .....................
Drainage ..........................................5s:
Climate ...................................................
.< ...
.....................
....................
v-:-
.
..__
5
6
9
9
9
10
10
10
11
..\....
.
i......
Animal life .......................................................... 18
Settlements and population ..............
..................... 20
Communication ........
....................
. 21
Dacriptive geology.........
....................
... 22
General featur ep .......................................................
22
Carboniferous greenstones and nssociated sedimente .....................
23
Areal distribution ................................................... 23
Lithology ........................................................ 23
Structure ........................................................
25
Age and correlation ...............................................
26
Cretaceow sediments.................................................
26
'Areal &.tribution ..................................................
26
Lithology and stratigraphy ..........................................
27
Local feature^. ...................................................
28
Anvik River ..................................................
28
Koserefski River to Mountain Creek ............................
29
Dogfish Village ................................................
29
Devils Elbow .................................................
30
Marshall ...................................................... 30
Chvilnuk and .4 ndreafski river b a s h .........................
31
Structure........................................................
32
Age and correlation ...............................................
33
Tertiary sediments ...................................................
35
Quaternary sediments ........... .1 ....................................
36
Agencies and processes .............................................
36
Older ailta and gravels ............................................
37
Modern stream deposits ............................................
41
Or@
depoeits ....................................................'43
Igneous rocks ......................................
.-.,
............ 44
Greenston& .........................................r-. :..........
44
Soda granites, quartz diorites, and diorites ............4"
,..:, . ..........
4.4
Dacitites and andeaites ..............................
/52:?, ........ 45:
9
:
B dts....................................... -. ;
.a,
.=r
53
3
C
...
......
47
\.......
47
. 5.
Distribution ............................. r..........
.....
8..
Lithology .............*.............................
- ;
Age and correlation
,
,:;,,, ,
4
.... ..............
: .
...
. . .
4
48
-
fl
*:-
.
-. ,M d c q a n B ' - ......................................................
.'rb,,,..,ygs..................
@ ! ! , i c time..
.. .............................
"
:*
- .-
Quaternary prid.. .l
,
Mineral resources..
Hiotory of rnining.development..
Economic factors affmting mining.
Gold placem..
W i h Cmk
Willow Creek.
.;
Other&eams
Oold lodee.
. -Anthony
-.T-4,
*,
.-.;;.-c;;i
................................................. I. ;....
.......................................
....................................
.......................................................
................................................ ....'...
............ .....................................
....................................................
................................................. ,. . ...
..........-................
..........*..
!
-
G;;.
.................................
........................................
................................................
............ .,..,;:....-,+..$.?+
&-5.i&i~&S:-.
*....
Index .......................................
..:.: ..... ;..-................
--d
.-
62
63
64
W
64
6
6%
69
--
~
Pam.
I. ETopqmphIc reconna~s9ancemap ol the Aavik-AndreniskE re
p;lcin -,,,,--LI------II n pocket
IT. Tupopphlc map of the Marshall seining d h t r l c t - - - - Inpocket.
111. Q ~ o l o d creconnalasance map of the Andk-Andreaiakl reglen-------*----I n~ k e t .
f V . Geologic mnp of the Marshall mlnttlg d d r l c t - - , In pocket.
V. A. Emlnnnl embaym~ntin the hank of thr! Yukon below Holy
Csncra: R, Altlplanatlon terraces and soltfiurtlon elopes enst
nf Faith Creek--,,,,-------------22
TI. A , Rnsalt aike cruttlng horizortnl bnmlt flows 26 miles above
Inmumhart; B, Low Ln peat In the wmt bank of the Yukon
T
-
,,,-,-I-----d
-----
5 tuiles below AarIk ---,,,,,,,,---------Zj
VIL A, Sinter cone of one of tbe soda sprlnga near Marshall ;, B, A
pottion of the mlolng camp on Willow C m k above Marshall-,,-,,----,---,,
- - - - - - - 80
---,
TflE ANVIK-ANDREAFSKI REGION; ALASKA.
FCEW WORK AND ACKNOWLEDUMEKNTH.
*.
"
This report is intended to cover the lasulta cf the explorations of a
United States Geological Survey party during the summer of 1916,
in charge of R. H. Sargmt, topographic enpneer. The writer was
attached to the expedition as geologist, C. F.Bailey acted as recorder,
and C. E.Anderson as cook
The party was landed frm the steamer at Anvik on June 16, and
carried on work from, that time until a 'steamer was boarded a t
Andreaf~kion September 13. A 20-foot poling boat quipped with
a 2-horepwer engine of the detachable hang-over type was the
principal means of transportation throughout the summer. A
topographic and geologic trsverse was msde on the Yukon from
Anvik to Anhafski and up Anvik, Bonmila, Stuyahok, and
hdraafsk: rivers as far aa wwss considered practicable under tbe
Limitations of the short season. The intervening strekheg of county
inacmwible from the h a t were not visited. Tn addition t o mnking
these traverses along the streams, the party spent 16 days in the
vicinity of Marshall in studying the mineral m m s and in
topographic and geologic mapping.
The writer wishes to express to Mr. Sargent and to each of the
members of the party his appmiatim of their cordial aid in the
furtherance of the geoIogic work on every possible occasion. To
Rev. J. W. Chapmoanand others at Anvik who misted in the preparation and equipment for field work the members o f the party feel.
their indewness, and to every miner, prospector, and merchant
met during the summer thanks are due for the unfailing hospitality,
the spirit of ready cooperation, and the unflagging interest in the
carrying on of the Survey work Such aeistanee made doubly
,efficient the efforts of the mernbm of the party where reliance had
to be placed on other than their own efforts or equiprrient fop the
prosecution of.the work.
Ih the
officithe m-bers of the division of Alaalrsn m i n e d rea
wmw h* e m n d d &nee
in many waya, arid the writer is
6
+
-.
1.
1
especially indebted to R M. Eakn and A. G. Maddren, whose work
in near-by provinces has elucidated 'obscure physiogrsphic and
gmlogic problem .in this region. Grateful acknowledgments are
made to 6. B. Mertie, jr, for assistance in making petrographic
determinations. I?. H. &owlton end 3. B. Reeside, j ~ . determined
,
the fossil collections obtained during the summer.
EARLY HIBTOR'P AND PREPIOTJ8 WORK.
Although the coast of Alaska had been early explored by the Enssian and English navigators, the interior country was wholly unh o w n , even after a considerable trade in lam had been established
along the m s t . Of *e many who explored the Yukon, Glazttnof
appears to have bPen the first. He reached Anvik from St. Michael
early in 1834, cmgsing the portage with dog& After c k g to the
Kuskakwim, he returned to the Yukon and apparently reached St.
Michael by way of the mouth of the river. He mar followed in 1838
by Mallakof, who crossed by the Unalaklik portage and swended the
Yukon as far as the mouth of the Koyukuk. The next summer he
reached tha mouth of the river by boat. In 1842 Lieut. Zogoskin, of
the Imperial Russian Navy, tmvemd the river from its mouth to
the vicinity of Nulato, and in 1844 he reached the mouth of the
Nowitna. He pmpard a map, which accompanies the report of his
explosationa2
. The earliest geologic work in this portion of Alaska wss done by
W.H. Dall in 1866 to 1868, while he was in chgrge of the sientific
corps of the W&m
Union Telegraph Co.'s expadition. Re made
a traverse from Fort Yukon to the mouth of the river in 1867, and
again went down fie river f q m Nulato 'hSt. Michael the following
summer collecting geologic and other scientific data. His narrative
contains ~bmap and some geologic notes, but mom detailed infometim is tu be found in other reports4 of s more technical character.
W h p p e r wm an associate of DdI m d the artist of the blegraph
expedition. H e d s t e d in gathering data which were doubtless used
in the preparation of his own books and that of Ball. A map of the
Yukon and a smalI-scale mtxp of Alaska are included in his account
of his travels with Dall.
*Brook& b. H.,Vnpoblhhed r n m u d p t
-,
*Zaga8kIn. f*, TrateIa on fwt and demrlptiun of tbe Busslam pmonl In
from 1842 t0 1844, St..Petersbnrg, 1847 (In Rnnslalatl) ; d m In German In Flrman'a
Arcblv inr rhemscbmttZlche KunPe w n Rllsaland, 101~.6 and 7.
Dall, W. H., Alaska and I t s resource, 187il.
*D&lI. W. H., and Hasrls. O, n., Cors~lntlonpapem, Neocem: U. I.Qml, 8 n m g Bull.
Report on rod md Ilmltn of dlaaka:
84, pp. 282-2W and map, 1892. Dall, W.
r[l. S. Qeo1:S-Y
SerrnMnth h n . Rept., pL I , 9p 7 M 8 , f8PB: Bamtw Nor, N a t
H b P . hoc., vol. 12, p. 138. 1888 ; J k p l O ~ ~ t l oI
nn B e n Amcrtca: dm. Soy!. Bet, W
w.. WI. a,p p 91-89, 1888.
WbymperI -etlck,
Tmrd nnd adventurn in the -tory
of A I u k .
&.
+
'&-.'.-
*.
&
Upon the acquisition of the territory by the United States, one of
the questions to be Atled was whether tha Fort Yukon post of the
Hudson Bay Co. was on American or Canadian soil. To determine
this point the k t of the expcbtions under the auspim of the United
States Army into interior Alaska was undertaken in 1869 by Cngt
Raymmd.a His party, consisting af himself, John J. Major, and Pvt.
Michael Foley, obtsined passap on the small steamer I'ukon on its
first trip up the river. Observations were taken at St. Michael,
An*,
Nulata, and Fort Yukon to determine their position. Asgisted by Major,,he msds lp traverse of the river while ascending it,
using the time and m m p w method. After observations had been
made 4t Fort Yukon, the party descended the river in a small boat
and c m d to St. Michael by the Anvik portage. The results of Raymond's survey# appear on the map compiled by him and included in
his report.
T ~ party
B of Lieut. Schwatka made a miIitwy reconnaissance of
the Yukon in 1883, and Charles Homan, attnched to the party as
topoppher, made a topographic sketch, map of the ~ g i o n .
. Rusarell
was the first geologkt detdIed by the United States Geological Sdrvey to make studies in the Ynkon VaIley. In 1889 he
accompanied the Coast and Geodetic Survey parties that determined
the location of the international bonndsry where it mxsa Yukon
and Porcupine rivers. F m the nature of his trip he was afforded
but scanty opportunity for mwking geologic studies on the lower
Ynkoa,' but his report contains many significant facts mgnrding
physiographic features.
With tbe development of geld mining in Almka prtrties were sent
by the Geological Survey to investigats the mineral resources and to
make snrveys in the produchg xegiona In 1896 such a party, in
charge of 5. E. Spurr, with H. B. Goodrich and I?, C. Schrader as
geologic &stants, undertook the study of the mining camps in the
interior. They descended the Yukon from its source t
a its mouth,
bvestigating on the way the Fortymile and Birch Creak districts and
making extensi~estudies along the river as far dawn as Nulato, A
small-scltle map6 of the lower Yukon ammpanies the report
of this invwtig*tion. From infamation obtained an this trip
and on a trip made in 1898 a geologic reconnaimnce mAp of south-
5
-
.
* mmond, C. W., Report of a r m a f w n c a o f tha W o n Blrw, A h k n Terrltorg,
a d COP#., lat -,
t3. Ex.
IS, 1871.
~ B f h w s t k ~FmIerIck,
,
Report of a mUitnry reconnalmn8a Id AI-ka d m In lE#,
." 48th Cong., ad eess., B. Ex. Doc 2, lw.
f i a u ~ l l I.
, C., Nolee on the amface geology af dI-b: Gml. 80c. Amtlca Bull.,
$01. 1, pp. 90-162, 1890.
cgpqrr, J. E,.Qtulom 07 the Pnkon mid dIatrIct, A b k a : D. 8. -1.
Barvey El&.
w n t l i Ann, &ePt., pt 8, Pp. gZ-392, 1898.
.Idern, p. If@.
.
weetern Alaska waa prepared."
mhp of! the Kuskokwim-Yukon
portage' was mmpild from notea taken by F. 6. Winckley, one of
Spurt's adstants, who em& to the Yukon by way;af the porhge
~ n thence
d
down'tbe Yukon tu St. Michael.
In 1902 Colliera spent the mason in an investigation of thm -1
resources of the interior of Alaska, Sidney Pnige mi& him and
made a canoe traverse from Eagle Ito Pairniut. Collier's report cunI t a h a mapt showing the distribution of the coal-baring terranes
in the Yukon Valley. The base map is a compilation of previoussurveys but includes also the results of Collhr and Paige. In addition to gathering data regarding coal, Collier made extemioe geologic
notes which have bean available to the writer in the preparation of
this report. h.olrder to make stratigraphic and p a l ~ n t d o g i cstudies
A d n r Hollick, with Sidney P s i p 8s his assistant, revisited in 1903
the loclslities from which fossils had been obtained by earlier geologists. The results of their collecting hare been available to later in, vestigators md are being utilized in the prepsmtion of the monographs by HolEick on Alaskan Crehceoue and Tertiary %oras.
In 1907 W.W.Atwood, with H. M. Eakin as his assistant, midtmk further studies and descended the Yukon es far as Holy Crose,
where the mmn's work was c l w d The following year M a d d m
spent a portion of the field mason in a h d y of the Inaoko placers
and made material contributions to the existing kno+ledge of t b ~
plrrgy of the lower Yukon region. Maddren's explorations were
followed in 1909 by the expedition of Smith and E a h ' between
Nulato and Norton Bay and in southeastern Seward Peninsula The
d t a of them expeditions are of great value in the interpretation
of the gmlogy of the ereas lying south and southwest of the regions
traversed by them, but larm areas that are geologically unexplored
Eie between tha m a s previously sumeyed and tlmt mapped in 1916,
The Marshall district had not previowly been visited by any member of the Geological Survey, but notea on the mining operatiom
on Wilson Creek nnd on the general conditions in that vicinity were
obtained by H. M. Eakin in 1914' and by A. H,B m k s in 1815.'
Besides the inveatiptisns by the pwtiss of the GeoJogicsl Survpy
work has been done by members of the Coast and W e t i c Survey
,
.q
.
\
* ipurr, 1. BI., A ~ n a a l r s a n c ein mtbTwenmh don, Bcpt, pt. 7. p. 284,1800.
g ltbm, p. 08.
a Colller, A. J, Tba -1
rcmUrw d the Y
1803.
4 Idp 10.
Maadten, A. O,, Thsr fnnoka gold pnleer
1910.
Nmkn tn 1m: U. 8. Osol S o w
&
m dt.Lr: U. B.
QWR,
. .
Aln8h :W. B. -1.
h
r
w BuU
~
21%.
Wmif I h I L 410,
nsmlth, P. a, mnd makin, H. M.. A mlog!c mCOn~baneein mthea#teru S c w a ~
pemtnmla and t
k Norton BapNnlato regton, bE&
: m. 8. GeoL 13nne;l Bthl. HD, 1811.
U. 13. Oml, B t v r s ~Bull. 822, pp. 8 5 4 6 , 1915.
*U. 8, Uml. B m e j BuU. 842, p p ~67-08, 1916.
'
a
Y
i
-
in this and adjoining regions. Commencing in 1898 and extending
aver tbe following season, several parties were engaged in charting
the ghom 08the Yukon delta, the mouths of the river, and the main
river as far ns as And~afeafs T h e work dong the river a d the
&ores of Norton Sound was controlled by triangulation and includes soma topographic as well as hydrographic mapping. ' The
work of the Geological Snrvey party in 1918 was dons in-sn area
adjoining that, mvered by the earlier work of the Coast and Geo.detic Survey parties, of which a portion h ~ been
s
used in the preparstion,ofthe accompanying topographic map (PI. I).
In 1908 s, series of magnetic stations along the Yukon were occupied by J. W.Green, of the Coast and Geodetic Survey, and magnetic and astronomic observations for latitude and ldngitude were
made in the region covered by this report at Anvik, Holy Cram,
Itmian Mission, and Andreahki.
LOCATIOB.
The Anvik-Andreafski region as described in this report embrace
tb m t o r y west and north of the lower Yukon RiPer between Anvik and Amdreafski xivew and an extensive area of low-lying coimtry immedkhly contiguou~tt o the Yukon on its east and south sides.
Extending from longitude 159" 40' to 1 6 3 O 20' W.and from latitude
61" 30' to 6 3 O 40' N., the area co~eredby the surveys in 1916 is
ripproximately 2,000 square miles. The map of the Marshall mining
district (P1. II,in pocket) covers the area in which mining is being
done,
NO~IENCLbTITBE.
C,
d
The history of the And-hdreafski region throws light on tho
swam of the names of the towns and topographic features, These
namee are in part in the tongue of the two native races that h t
inhabited the region. Later the R u ~ i a nlanguage furnished some
.names, and tfis advent of men of English-speaking r- brought
a b u t other changes, modifying some of the earlier names and
substituting new name3 for others.
So far as pmible the names in most common use have been employd on the topographic maps (Pls. I and 11, in pocket) and in this
_ text, Iboth native and English names are known and both a p p m
,20 tw used to about the same extent, the native name is given prefenmm. For a list of the names of the natural features in the vicinity
of Marshall, many of them applied by the natives, the survey is
indebted t o Mr-Frank Waskq.
- ~~f
and W e t l c Bumey chart 0370, Cape Eamanzoi to 8t. Michael, Alaska.
,
In naming ~ o m eof the creeks the Englishgpesking minem have
exhibitid the same poverty of vocabulary or lack of originality that
is to be found inmany other mining districts. The repetition of the
-commonern m m fur creeks, such as Spruce, Willow, Rear, and Rat,
in almost every district in Alaska kads to such confusjm that in
order im be dearly understood it is frequently necessary to refer not
only to the district jn which the creek "l found but to the larger
-stream to which the particuIar creek is tributary. It may even be
necessary to n a m a third or a fourth stream into which the smaller
one flows in order to maka identification positive. It would geem t o
be false modesty which inhibits the discoverer of a creek from naming it after himwlf. His name applied to it usually has the double
advantaga of giving it individuality and of having historic valua
.
3
In general, the relief of the region is slight. The highest point
attains an altitude of about 9,700 feet! and there are comparatively
few mall isolated aress lying above 2,000 fwt. Along the west and
north bank of the Yukon the snrfnae is in places sharply dissected,
but as a whole the forms are those of a mature topogr~phy,so that
the country presents a rolling aspect Wide, poorly drained lowlands occupy the intermontane areas.
Tha uplands are scarcely high enough to merit the term mountains,
although here and there a point r i ~ well
s
above the general level
and furnishes a conspicuous and easily identified landmarlr. Of thia
charactsr are Bonasila Dome,'Chiniklik,~ n Pilcher
d
Mountain.
8onasila Dome lies east of SStuyahok River and south of Bonasila
River, and its imlatiop, together with its peculiar form (a cone on
the crest of a gently crowning dome), gives it prominence from
whatever point.it is seen. It is sometimes called Simel Mountain. '
The highest and most mnspieuous peak in the region is tht known
by the guttural native name of Chiniklik,frequently corrupted by the
whit- to Cheneegly. It appears remarkable that so high a peak
ehould be only 4 miles from the Yukon. It lies 8 miles above Russisn
Mission and
miles below Tuckers h i n t . This mountain was
Men from points along Anvik River, from Andreafski, and from
p r a c t i d y all the intermediate statipns e m p t those! a t the water's
edge on the banks of the Yukon. Its conical outline, with shor~lders
a few Bandred feet blow the apex, readily identifies it. This peak
c
5
..ri
3
is visible from many points along the crest of the divide between the
Yukon and Andreafski drainage basin and from points f a r south of
the Kuskokwim.
Pileher Mountain lies about. 5 miles east of Marshall. It rises
well above the immediately adjacent hills, and is topographically
prominent because of the exceptionally well-developed altiplanation
terraces on all sides but the southeast.
The areas occupied by the softer sedimentary rocks of Mesozoic
a& are everywhere, except near the Yukon, marked by the gentle
slopes and rounded crests that are characteristic of a mature topography. Elsewhere the drainage is that of an area past maturity in
the cycle of erosion, but the crests of the hills present-a terraced appearance (Pl. V, B, p. 22). The origin of these forms has been described by Eakin; who termed the process altiplanation. This feature
is discussed further in connection with the Quaternary history (p. 55).
The terraces are best developed in the areas of igneous rocks i t the
higher elevations. To a minor degree altiplanation has taken place
in some areas of the more indurated sedimentary rocks, especially
in the viciniiy of iytrusives.
LOWLANDS.
*
The lowlands may be subdivided into two classes-those that lie
above the flood level of the Yukon and those that are reached by its
highest stages of water. The lowlands of the first class occupy the
broad erosional depressions that are characteristic of the region.
Bedrock crops out along the streams only here and there-not a t all
for several miles above their mouths. Alluviation has proceeded so far
that, except in their headward portions, the streams flow in meandering courses along which are many oxbow sloughs formed by abandoned meanders. I n the lowlands that lie within the influence of the
Yukon are to be placed the wide stretches which extend to the Kuskokwim east and south of the Yukon. On the larger tributary
streams alluviation has lowered stream gradients to such an extent
that they are controlled by the Yukon at all but the lowest stages.
Five miles up the Bonasila the writer saw debris which undoubtedly
came from the Yukon. It is therefore conceivable and even probable
that the alluvial material that is now being laid down over the bottom
lands along the lower reaches of this and other tributaries is derived
in large part from the overloaded flood waters of the Yukon, which
deposit a considerable portion of their burden in the slack.waters of
the embayments furnished by these stream mouths.
XEakin, H. I&, The Yukon-Koyukuk region, Alaska: U. 5. Oeol. Survey Bull. 631,
*4 -"lQ%-:2-,
?o the gwlogic structure was due the original pmiti~riand direotion of many of the streams, but other factors hqve affected their
hter. higtory, and the former coursk have been ~omewhatmodified
by aUuvintion and lateral erosion. The .valley occupied by Stuyahok,
Ronasila, and Anvik rivers affords an excellent example of stream
trend initially controlled by the underlying bedrack structure, and
the Yukon above Holy C r o s tmnds in the same generd direction.
Structurnl .control is also evident in the vicinity of Marshall and,
at least in part, along the, north fork of Andreafski River,
The region considered in this report lies wholly within the Yukon
drainage basin, but the wide, flat, Iake-dotted delta between the
Kuskokwim and the Yukon, opposite and below Rnmian Mission,
has so littIa relief that the watershed between the two rivers is difficulb of location. So far as w l d be wmrtained, there are few places,
except near the mast, that Tim even so high as 100 feet above either
of the rivers. At high &ages of wker much of this lowland is
inundated. During the spring of 1916 thesmall steamer Tam left the
Yukon throngh a slough near Pilot station and, entering Kashunuk
River, reached Bering Sea through h e n Bay. Essentidly simibr
conditions are tn be found in the delta of the Imoko. At high water
this river may be reached throngh any one of several mouths, from
a point gaveral miles above Anvik h the last slough, sbout 11 milw
blow PaimiuL Other trifiutsriea of the Yukon enter from the
west md north after passing through considerable delta a m s , which
are modified by overflow from the Yukon and truncation of their
hunts by that river. Bonasila, Kmrefski, Kuyukutnk, and
Chvilnuk rivers and many of the smaller creek enter the Yukon
thmngh alougha Lakm are characteri&ic of the flood .plains of
same of these irtrearns thronghoot their lower ~eachesand were
v i a l l y noted in the broad depression mupied by Kupukutuk
and Ghdnuk ri9ers, which resembles in this regard the region
between the Yukon and the Kuskokwim.
CLIXArn.
The clim~teof the Mk-Andreafski region is i n t e d i a t s in
character between that of the upper Yukon and the e
l region
fromNoftonSoundtaBrisf;olRay. ThepmximityafBeririgSen
haa a stabilizing influenee, so that the summer ternpemtmres are not
so high nor, aa a rule, the winter temperatures so low as those of the
upper Yukon, although north winds may occasionally bring about
similar conditions in the two areas. From the records the precipitation appears to be greater in this maon than at coast points and
almost double that of points in the upper Ylikon Valley. ' ~ i h n two
y
consecutive s e a m them is likely to be considerable djffkrence in
r
fie amount of rainfall and in the timea when precipitation takes
p l q but normally the *test
precipitntioa occurs after the middle
of July. In 1916 records were kept from June 18 to September 10,
indnsiva In the 40 days from June 15 to 3uIy 25 there was some
precipitation on 21 days, or 52 per cent. In the 48 days from July
25 to Sephmber 10 there was some precipitation on 35 days, or 78
F -L
t
MetmmIogic observations are available for Holy Cross, the only
&ation within the region at which rccorda have been kept for any
great length of time, but for comparison records are given for Tanana
and Nome alm in the folIowing tables, compiled from data obtained
from the United States Weather Rurenu, I-?jguresin the first three
columns are for 1915 only. The other columns are a summary of obawstions extending over several p a r a
m
r
&
a
of temperatwe at Holy Omas mmpared dtlp thane
in degree*
Date1
Of
lab
Fahrmhdt.
Nonto oad T a m
f d f l telmpwa2acre bn mdap and first W n g tempemturd
atct~rmma t Nanae, Help Cross, and Tanana, 1M5.
In
Fm5plfalion at N m e , Holy G m r , aalld TaRana,
'
- Recomb of the time of opening and closing of the Yukon at Holy
Cross have been kept for a, considerable number of years, and there
is p d 8 b l y normally very little differends between the btehl at tv.is
?paint end othem .asl far down the Yukon as Andreafski. ,These &tea
may+ summodzed as follows :
1
9begs* 63 Faa'ln aprfng betwen Aprll 29 and June L
.
~.~~.ir d laa b e t m u M a y 2l and June 8.
Xcs begnn b Eom 10 autumn between October 6 aria October 5 8
River Josed between Octob r 10 and Novemkr 8.
The rains are usually tmiught by southerly *Pin&,- and nottherly
winds prevail during periods of fair weather. The southerly winds
are fmqnently of such force as to impede navigation seriously, ns the
shambo~tsam likely to be driven aground on mrne of the numerous
barn of the river, and the seaa caused by the wind make nnavigatiw
dangerous for any mall boat exmpt a dory or one of the skin boboats
of the ngtives. The activity of the wind as an e m i v e agent was
observed many times on the a n d bars in the river, for ss soon as the
surface became dry the sand would drift before the wind and pile up
in mall irregular hummmks or dunes. Cross &ions of dunes thus
formed are e x ~ here
d and there in the cut banh of the Yukon.
-
TE(3ETATLOZP.
Within' the n m crossed by the expedition of 1916 the' conditions
aflecting vegetal growth are so diversa that a corresponding diversity bf plant types is reasonably.to be expected. In the vicinity
of Anvik the lowlands am well timbered, although an approach to
the tundra conditions foand .below Andwtlfski i s presaged by the
lowering of timber line compared with upper-river points. In the
vicinity of Anvik, timber line is s h u t 600 to 800 feet a b v e the river,
though in favomble localities, such as sheltered, well-dmined valleys,
it extends somewhat higher. No spruce was seen growing on the
Yukon below Andraafski, but scattered stumps of gpruce and an
occasional stmgg1ing birch indicate e former scanty growth of these
trees to devstions from 100 to 206 feet a h v e Andreafski: River.
From the hills back of Andmfiki small patches of spruce may be
soen mattered through the cottonwmd and willow thickets that extend along the Yukon above this point. The h s t growth of spruee
mre found along gullies, on slight eminences in the lowlands, or near
the banks of streams. Farther back from the smaller 8tmm in
the lowlands, where drainage is pmr, the growth is usually scatted
and stant&. Wherever spruce is found on well-drained bill slopes,
bimh generally mcum-ah, together with small-leaved poplar or
quaking aspen. Extensive growths of t h m traes are appemntlp
Jess common thsn in the Tmana basin. On Anvik m d Banasila
rivers the bimh bark is nwd by the natives in making their m o e s
Tamarack grows in very open g r o v i
~n the more b o g y plem along
the Anvik and Bonasila and was seen hem and there alrmg the
Yakon*
T?rroughout the lower-lying portions of the a m , cottonwwd and
eeoemI species of willow constitate the moat eommoa element of the'
forests. Some of -the bars that have bsdy emerged from t h e . *
are covered with a dame growth of willows a few inchm hi@.
In the driftwad along the river.there a p m Co b1em,miflm
pnd p o $ b n w d ~ @ . nsprqce, Fmm this it would ssam thst i, cop
r
+
a
-
.r
sidera'ble a m a n t of tha drift has come from points farther up the
liver, where the proportion of spmm is greater than it is within the
Amik-Amdreafsgi region. It is probable, however, that the preponderance of vruca in the driftpad may. be due partly ta the fact
that it rotg less easily md is not ao qnieklg waterlogged.
hiders am fomd throughout the region a t considerably higher
elevations than my timber trees, They cover the slopes, in places
&g
almost at the crests of the hills or ridges, where mme proM i o n is sflorded by the depresions in the hadward portions of
the streams.
Berries of some variety can be found in almost any part of the region. Blueberries are m m o n on the fairly q n s l o p . hw-bush
crankrries are fonnd with them or at somewhat higher elevations
and where there is little or no bmsh. The soft yellow salmonberry
appears to grow at almost any elevatio~but seems t o be most abundant in situations less well drained than those occupied by the other
berries, The bitter high-bush cmnberry was found in shady places
along the river bank associated with red and black currants, which
were also found on the drier, sunny slopes, together with red raspberries. Neither currants nor raspberriw were seen .in abundance
mywhere.
Grasses nm rmrprisingly plentiful in variety and amount everywhere in the region, so that horse feed could easily be obtained for
outfits traveling by pack train, especially along the tributarie of the
Yukon. On tbe Stuyaholr there a r e many beautiful open parks containing luxuriant grawths of pass, and at almast every point where a
&ap was made there was an abundance of forage. On the hilltops
and most of the slopes a large part of the vegetal covering consists of
moms. and lichens, but considerable horse f e d is still to be found
even here. On the river bars there is usually an abundmce of the
rariety of E p k e t u m called mare's-tail, and occasionally the pea Pine
is found.
5
When the party left the field (September 13) them had been no
frosts of mifficientseverity to destmy the nourishing qualities,ob the
grasses, bnt the season of 1918 was probably exceptional in this respect, and killing fr&
may ordhsrily be expected eady in September.
Fairly extensive agricultuml operations have been carried on for
a number of years by the m&on at Holy Cross. The native g r a w
in natural meadows on the floodplain of the Yukon below the mission
- .,+re cut and cured for forage or are utilized BS paA considerrie.ty of vageihbles are grown for private osa Any surplua
is sol ~ n finds
d
a ready market along the river. At Anvik some
%srd*
ia dwe, asd wveral varieties of
matar& The
mbhqe
'4
~~tzr,m
-
senson without frost appears to be slightly lonpr herethan farthar
up' the Yukon. Along the lower canme of Anrik River are g r ~ s m v s d areas a h w t wholly free from brnsh or timber. Thew nstural meadows couId doubklem be used for pasklre or the grass
cut for hay. 1Simil~rere= were seen on some other streams, but there
appear to be few along the Yukon.
An attempt wart made to procure a represantative ao1ldon of
flowers and p-, so far as other work permitted, but no Irxge
shrub sr trees were obtained. The collection was submitted t o the
Unitad States National Museum, and the following species were identified, the p- by Mrs. A p e e Chase, the Pteridophyta by William
R. Maxon, and m& of the other specimens hy'PauI C. Standley:
'
Alnpecroms alpfnoa J. E. Smith.
s p h a d o t h e ~ ~hydroplperla batdalfs
Qlnton
(on Bistorta Plamosa
( S m d ) Greene).
Calnmagrmtls canadellirla
Beanvols.
Fmtuca altalca Trhlnk
I
{Michaor)
Poa mrnpressa Llnn&
aad0nts i a ~ t a l ~adrmm
?
( Acharlua
Flotow.
adonla
dehmta
extwaa IHm- Carer anemma Linn&
Edophorum angusUfoElame aQtb
mann) Waiola
mchatus plummo~
(Rmch and Schlmper) lbth.
PolytrI~ham commune LInnC (near
var. nligino~umE-IIlmer)
Polytrlrburn commune T h n b
Polytrtchum strlctum Banka.
Sphagnum drnbrlatum Wilson.
-nocladas
.
~rym6rfsdllahti (Hoffrnann) Gray.
Dryoyterla dryopterle (LinnfiE Rrltton.
Dryopterla fragmm (LlnnE) Bchott.
t.
Pobgonom daskamflrn ISmalI) Wight
R u m 00~1d8ntaltsS. Watson, form.
&nnrla d c a Steven.
Cwadnrn alphum LlnnL
Merckla phpodm Fischer.
MoehrLngia laterlflora (Unn6) Fenel.
Dryaa ocbopetala Linntl
Poteatllln nivea Llnne.
Potentill* vlllom Pallas.
Rosa aclcularl~Llndley,
Rubus arcticua Llnne.
Itubus chamnemoru~Elan@.
dconitnm BelphlnifoUnm De Candolle.
Anemone narclssiflora L h 6 .
Snnguigorba ~ItchenslmC. A. Meyer.
Spiraea steven1 (Bchnelde~) Rydberg.
Anemone richardsonl Booker.
Batrachltrm 'iqnaMe (Llnne) Wlmmer.
Caltha palu8trLa ~PCHCR(R. Brown)
Hllth.
Rannndns reptam Limee
Yloh blflora Urine.
Viola langdorfii Flmcher.
Vlola pallrgtrls U n n t
h b l s mtn Intermdia (De CandoIIe) Wight
Barbar(LinnC) MacMlE
Ian.
Cnrdamlne pmtemh LinnK
hmba Im-eaFla De Cnndolle.
Radicttla paIustria [LlnnB) Mwmh.
Chamamdon angwMfollna (bnnh)
Smpoll.
C~amnenwloa latlfollurn (LI a n d) ,
Sweet.
Eplloblum dav~rlmm~1-m.
Bupleurum amerlcanum LlanB.
Clcnta dougtasll (DbCandolle) &utter
and Rose.
eORlOACEAk
~dtrnk
F F ~ J ~ L ~P
UU~~~AI L
H
Saxifriraga&cab Don.
B~~&"-ILBUU.
6
6
2
M o n w ualflorn (Llnn6) Gray,
'
Em-
Ledma d m m b e m (Aton) fio8dlgec~.
Loiseloria pmcnmbos (LhM) Desvaux.
Pbglldace caerulea (Unn8) Grenfer
and Godron.
Therorhodlon glamlu1osurn StandIeg.
Oxymmma o z s m s (Unn8) M a c
Mfllan.
Vaccinlnm caespltmnm Michaot
Tawhiurn vitls~IdaeaLInnR
Qentiana glaum PallHiernclam Wpte Wllldenow.
Taraxacnm cerntophom [Ledebonr)
I)e Onndolle.
Pokmanlum aeutlfloruin Willdenaw.
Polemonrum hurnlle Wllldenow.
8moP-w
I
Arnica I w l n d ! (TO&
(ireem=
I
Aster dbirlnls Llnne.
Senedo reserl Iforius Leasing.
and Gmg)
a
Animal life b ab~mdknt,'but there is little la- game. Only ono
small black bear was seen, h ~the
t tracks of black bear were fairly
common along the sand bars, and brown bear were r e p o d . %ither
caribon nor moose were seen, and it is said that there are none in this
pnrt of Alaska. Their former presence in great numbers is recorded
r-
.
.
.
.
by the earlier explorem, and on some of the ridges their trsils am
*
w
5
&ilI
visible. Domesticated reindeer a m herded in the southern
part of the region and small bands are pastured naar Marshall and
Andreafsli
Of smaller animals a few rabbits and fox^ were wen. The tra~ks
of the foxm were frequently observed along the river bars, where
they had been stalking the aquatic birds. Beaver dams and houses
were seen on the Stuyahok, and thaw was also evidence of the prmmm of ermine, mink, marten, md muskrats on this and other
streams. To judge from their tracks, porcupinks are fairly common.
The red-backed mouse was frequently observed.
Du& were seen almost constantly on the streams tributary to the
Yukon. G e m were abundant on tha Stuyahok and lower Bonasila, and in the fall they were seen in Bocks of hundreds on Yukon and
Andreafski rivers. h r e flocks of ducks were alao seen on t h e
Andmafski, as well as smaller Awks of m a n s and cranes. Near the
banks of the rivers some individuals of the several spspecim of sandpipers, snip, and plover were almost always in sjght, busily engaged
at the water's edge in search for food.
'She land game birds were exception"a1lys c a m Ptarmigan were
seen but twice, and o d y one grouse wss seen during the summer.
Other birds nohd include loon, tern, gulb of severs1 species, horned
. owl, haw'ks of mveral species, kingfisher, raven, t h m species of swallows, junm, three species of sparrows, varied thrush, hermit thrush,
robin, warblers, waxwing, Canada jay, and shrike.
On clear-watar streams that had a p o d current grayling were
taken with a fly, and no difficulty was experiened in getting as many
as were deired. Occasionally a trout was caught, but the tmut
- seemed lw nnmerous than the grayling. Fish wheels m d fishtraps
are used on the Yukon for catching mlmon ltnd whitefish. The salmon a m m o k d and dried or mlted down to be eaten during the
winter, by dogs as well as men. The whitefish are used largely as
summer feed for the dogs. Trout, pike, and pickerel are also said to
be t a k a by fish wheels or in nets. CoasidembIe quantities of fish of
mrious kinds are caught in large dip nets, which are handled with
wmmmat.a skill by ,the natives. In winter whitefish are caught
through holes in the ice by the natives, who use for bait an nrtificia1
minnow made of bone or ivory.
On Bonasila River large areas were noted where the willows aria
alders along the banks had been almost entirely stripped of their
foliam by m a l l w o r n , probably the larvae of a small black and
white b u t m y which was especially common. In places nlso the
willows were infested with small black wwvils, which were doing
considemb1~damam
'
,
-
'
A certain proportion of klaska'~inhabitants may be t e h e d IiteP
nlly a "floating " population, and for many ef them, both whim and
nstives, the act of changing their abodes in summer consists in lmding their few neoessities into boats of sume description and traveling
by water to places mhem employment may be had of where there
exist more favorable conditions for obtaining food by huntirig or
fishing. A p t number of the natives live in tempomry fishing
camps during the summer but asemble; into villapa in the winter.
The population of many a mining csmp is evanescent, and winter
finds the workers greatly diminished in numben, the quondam miner
having become a prospector or trapper and sought other scenes for
his activities, or he may have left Alaslra for the winter, ta return in
the spring. The following statements ius to the population of the
Anvik-Andreafski region should be considered with these general
conditions in mind,
There are permbent white reside& at Anvik, Holy b,
Mar&all, and Andmfski, and a few othem have trading pads or h h i n g
stations a t other points on thi+Yukon. There are also white teachem
at Pilot station and Russian Mission. On Anvik, Bonasila, and
Stuyahok rivers Cm cabins which are used in winter by prospectors
and trappers. It Is said that whim have also h e n built for winter,
nse on the Knyukutuk, Chvilnuk, and Andreafski. Marshall i s the
point of transfer for the supplies for the mining camp on Willow
Cmk, aboat 74 milea away, which is the largest cenfer of population
in the region. 1n August, 1916, none of tha cabins on Wilson Creek,
which lies between Willow Creek and Marshall, were -pied,
although considerable mining had been done on ita tributaries earlier
in the season. The white population at Mamhdl and on Willow
Creek in 1916 wae about 225 and at a~ other points from h v i k to
hdreafslri, including these villages, about 35, a total of 2&0.
The natives ere of two stucks. Those above Faimint sre affiliated
with the Athapascans of the upper Yukon. Tho* at and below
Paimiut are .affiliated with the natives of the mast but show slight
diflerenoes in dial& At each of the towns in the regon except
Marshall the natives aco moie numerous than the whites. Many
native villaga are mattered mlong the Yukon, some of which are
temporary and some permanent, having solidly constructed log
houses, caches, and drphg houses fur the summer catch of selmon.
There a m no permanent native v i l l ~ p
in the mountain on^ calmtry
an the west and north bank of the Yukon. Ruins of old deserted
~iIlap
were seen an the Anrik, and early in the spring the natives
make a trip up this river t o h h and to build boab, but nothing like
a pemment camp was seen. It is mid that the native also fre-
f
=
,
,
.
I
L
*'
-
quently make portages from the head of Mountain Creek to the headwaters of the Stuphok to fish and trap on that stream, and they
then deft down to the Bonasila snd the Yukon to avoid the return
portage., The native population includes about 200 a t Anvik and
along the Yukon Getween Anvik and Holy Crass, 200 at Holy Cross,
and 300 in the Znnokodelta. Between Holy Cro& and Russian Mission there are about 70 natives, mostly a t Pnirniut. There are 150
at Russian &on
snd in the villsgs between Russian Mi&on ttnd
MarshalL About 750 make their homes in the area htween Marshall and St. Michael, and of these perhaps 120 are st Marshall and
Andreafski and between these two villages. The total native popalation in the Anvik-Andreafski region is nesrly 1,000,of which about
700 are of the upper river race and the others Mong to the lower
river or coast stock. .
Schools have h e n established a t many of the villages Those st
Anvik and Holy Crass nro sectarian, and most of their &dents live
in the s c b l dormitories, Government mhmh are maintained at
Russian Mission, at Pilot station, and in the Innoka delta a t Shngeluk. Two Government teachers are also attached t o the mission
school a t Holy C-.
QOXMUWICATIOX.
5
..
In mrnmer practically the entire region is accessible by h a t .
Steamboats afford s ready means of transportation on the Yukon
and are run at intemals of a wmk to 10 days. On the Bonasilrr
there is sufficient depth of water for steamboat navigation to tho
mouth of the Shnysahok, where soundings gave a depth of 13 feet.
- All the larger streams are navigable by poling boats or smell launches
for considerable d i s h n m from the Yukon. The Survey party in
1918 used s 30-foot poling boat equipped with a 2-horsepower engine
of the detachable type. T h e Soat usually carried a load of nearly
a ton but, experienced little dificultp in amnding the streams that
were traversed and made good p r o p up the Yukon. An engine
of higher power, however, is to be recommended for a boat and load
of this size. A boat with greater frsebosrd than a poling boat is
also d&able for n e on the Yukon.
During the summer of 1916 a wirelcs ststion was erected at Holy
Crm by the Signal Corps of the United States A m y . This is the
only telegraph station within the region, but them are stations at
Nulato: Kotlik, and St. Michael.
Dnring the gammer there is a weekly mai1,service on the Pnkm
and throughout the year a monthly service betwsen p i n t s On K w
kokwim River and on the Yukon ta and above Russian Mission,
During the perid when naaigation is clmed there are fire mails
from SL BiLichd ta Marshall ( Fortuna w e post office) d intazc
mediata points.
@
E
m FMTUEES.
The principal mcks of the Anvik-hdreafski region are dih'ba t d mentially m ipdicated on the geologic maps (Pla IlZ snd IV,
'
in pocket). Much the same conditions prevail in this w o n as in
i*
many other parts of the Yukon basin, so t h a t although the general
distribution of the smveral units is ascertainable, their exact h u n d aries sre not redfly determined. Contacts are a h & universally
obscured by Quaternary dluvium or by a mantle of residual material,
produced by mechanical and chemical disintegration, which migrates
down the slopes and effectually conceals the distribution of the underlying rocks. Comminuted rock d4bris derived in this manner coven
the lower slopes (P1. 7, 3) and merges into mahrial of gllnvial
origin without perceptible break. It is obvious that in auch p l m
the boundaries of the alIuvium must IM generalized.
h reconnaimnce work Zike that done in 1916 it ia not 'yvoesible fo
trace out formatiosl boundaries so accurately that no asrtumptions
need be made. Topographic f o m , color of mka as saen from a
distance, indimtiom afforded by changes in type of vegetation, and
other forms of hdence are eonsidered, but inevitably there will be
some error in detail, although the w o r k q out of the majw relatione
may prove to be essentially oorrect.
In the vicinity of Marshdl there is an area of metamorphic roch
which extmd eastward to the Kuyukutuk and reappear along tha
Yukon below Russian Mission zrnd still farther east between Mountain C m k and Kosmfski River. Greenstones of e, rather wide rango
in composition and origin, probably embracing intrusive mcka aa
well as flows and tuffs, make up a large proportion of them metamorphic roe&
Closely m i a t s d with the greanstones are data,
quartzites, and wnglomemh and many intermediate mck types.
The greenstones appear ,to have auflered the mast intense changes,
but secondary structure has d e ~ e l o p din the gediments also. Undeformed acidic dikes cut both tha gmnstones and the sediments.
Although the complete solution of the questions involved in the
strstigritphic mquence of these rocks and their mutual ~.eletions
mud await more detailed study, i E is now tmtatively &ssmed that
the greenstonas, including the tuffs and mme oonglomeratea which
occur with them, are of late Palemoic qp and that the sedimentary
rocks are the metamorphosed equivalent8 of the CFBtaceolls beds
found elsewhere in this region.
Cretaceous rocka were found on h d k and hdreafski rivers and
probably occupy much of the intammhg area T h e principal rock
typas found are conglomerah, sandstonw, and ,shalq wMch b y e
?
'
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f7. S. GEOLOGICAL SURPET
BUT,LETI?; T,SR
PT..ITT YT
locally been metamorphosed into quartzik and slates. ~ h k u ~ h
tbm roch are generally thin bedded, with sn atreme phase of
dhmating sandstone and shale layers Iess than half Bn inch thick,
m&ve phases also m u r in which the individual beds may be severa1 feel in thiclmsss. More or l e a closely awxirrted with the Cretaceous rocks in the northern and eastern parts of the region are a
series of tuffs and flows of intermediate basic types. Some of the
flows appear to be intemalated with the Cretamas sediments. In
the southern part of the region are a number of dacitic porphyry
dikes of lab Cretaceous or post-Crebceous sge. It is probable that
same of the intrusions in the vicinity of Marshall took place at the
time these dikes were formed.
Na sediments of known Tertiaq age were found in the area, but
*
E
"
at somewhat widely separated points vesicular lavas occur as unde- formed horizontal flows (PI. VL, A ) , which are either late Tertiary
ur early Quakrnary. Quaternary deposits are found throughout the
region. They include the residual mantle or rock and soil on the
higher hills and slopes, the gravels, sands, and silts of the terraces
and lower hills, and the alluvium that occurs along the stream courses
almm to their beads but is most extensive in the lowhnds of the
Yukon and its larger tributaries.
WBBOWIB-MfB
CIBEEHSTONES AND ABSOWTED 81EDmENlrss.
AREAL DIKl!RBWTIOm.
,
Metamorphosed tugs, flews, and intercalated sedimentary rocks,
t ~ e t h e rwith some rock that may represent altered basic intrusives,
-mcur at a number of places in the And-Andreafski region. In the
vicinity of Mawhall they form a mmidembf- portion of the bedrock along the divide between Spruce and Wilson creeks, on the south
and mast slopss of Pilch~rMountain, and on the south slope of the
r a w of hiUs to the east of this mountah This s e r k o f rocks also
appears at four other- localities between the mouth of Xoserefski
River and Marshall, outcrops being found below Russian Mission,
in the vicinity of Baref ace Bluff, above Tuckem Slough, ,andfor.ashort distance dong the Yukon at the mouth of h a r e f s l d Ever. ,;
A large proportion of these mcks are igneOt19, but r m b o f ~ & & mmtrrry origin make up a minor part of the series.' Only in hhi
' ~cinitJr
of B a d a c e Bluff are the sedimenb notably abutdint.: In .
the area between Paimiut and fickers Slough a 'few thin be'& of
oq1memh am intercalated with the flows The congyohwb
p e b b l ~.con& mainly of igneous material, with lesser amounts of
cbefi. Green tudaceouls grits and sandstenes also occur at this locality in similar relations ta the flows. Small chert grains are fairly
numerous in m e of the coarser-grained beds. Here and there thin
beds of argillitic sand separate the flows. Below Russian Mission
occur some grits, the grains of wbich are almost w h d y gray and
blttck chert. In the m k s near Bareface Bluff greenish tuffs and
tufEaceous wdstones am asswiahd with red cherts and argillites
as well as with greenstone flows.
Near Marshall this wries is represented, so far as observed, only
by g e n m e flows and intrusive MC@ and the associated d i e n tary rocks are presumably younger, Several rather widely different
types, ranging from schists to rnapksive mcks, are included nnder the
term of p n s t o n w . At the bluff below Marshell the greenstones
are extremely whistme, much contorted, and netted with quartz
veins, which have also been subjected to deformation. One of the
quartz veins noted is 6 inches or moro in thickness. At Mnr~hall
the deformation appears to have k e n less inten%, although s =his-
*
?
+
*
tosity which gives the impression of bedding has been developed.
Elsewhere on the slopes of Pilcher Mountain and along tho ridge
east and west from Maunt Okumiak the rocks appear gneissoid
,
rather than schistose, with some massive phases in which but little
m o n d a v structure has been developed. Thesa various phases
appear v q different in the hand specimens, but under the microscope nearly d prove to be spidote-amphibole rocks, practicnlly
the entire rock being made up of these minerals, with a moderate
amount of magnetite and here nnd there small amounts of quartz
or chloritic minerds. Less frequently pyroxene and plagklarsa
feldspars may be determined.
These m b am all recrystallized, and there is some doubt aar t o
their original nature, but they probably represent a mehmorphosed
series of mdesita or basalt tuffs and flows which have included some
pbbmic intruaivm. This conclusion as to the origin o f the greenston- is confirmed by their composition at the localities b l o w rsnd
above Russian Mission, where they have not been subjeded to such
infen& metamorphic procam and their original nature is more
readily determiwble. The tuffs and flowa are largely basaltic, with
a u g i h and labrdorite as their principal constituents and magnetite
as the chief amwsory mineral. Some of the flows are a little mare
siliceoug the feldspars having the average composition of and*
and the rock is an andwit&. Secondary minerals have been. deveIoped
tokonris extent, mainly by the dteration of minerals containing i o n ,
foiming hornblendi, chlorite, or seqenkhe. Glass is found .inBorne
of the tuffs. '
. .
- - tk.4 &;?!:
.I
,
.
:
'1
,j
'P
'
8
Tntwives in the grecnmne series m r at .t anumber of places in
the vicinity of Marshall, where they cut the Cmhcaous mks $IN.
(See PI. IV, in pocket.) Sods granites snd quartz dibritRstRs
make
up the larger stacks, and the numerous dikes are dmite9. They are
d i s e u d under the heading of 'L Igneous rockg (pp. 4441).
*
-
.
.
r
-*
-
T h e stmctnre in the p n s b n e areas is rather complex. To some
extent it has been induced by thc jntrusives which have cut the series,
bnt for the most part it is related to broader arogenic features.
The intrusion of the rsda granite that forms the core of PiEcher
Mountain probrrbly produced the complex structure in the ares north
of Wilson Creek and caused a general doming effect in that area.
The strructnre south of Wilson Creek is open to two interpretations
and may have been produced either by close folding or more probahlp
by faulting. The outcrops in this area are rnnssive and afford few
structural data. It is notable that the drainage of this aren is controlled by bedrock structure. Between Rusian Mission and Grand
Idand the ~tructurecan not be determined, mainly on account of the
massive nature of the roc& both the,flowa and the associated sedimen& showing no deposition planes. They are, however, much
jointed, and dong the joint planes considerable movement has taken
place.
Tha sedimentary rocks above and below the mouth of Kako Creek
contain prominent joints and are in many pIaces broken by conqicuoas faults. h a i l l y the stresses are adjllsted by movements
along bedding plmss, but the effects of such movements are not
pronounced. For the most part these rocks have a nortbederly
strike ~ n da northwesterly dip, confoming to the regionaI trends.
Both the topopphy and the rock ~Ztitudesuggest that they are
separated by faults from the sedimentary series in the vicinity of
Do@h Village.
Where their attitude is determinable the greenstaws above the
entrance to Tuckers Slouglf strike northeast and dip. steeply to the
northwest. It appears likely that this dip is reverse, and that the
flows r e p ~ n an
t overthrust upon the younger sediments Faulting
has been extensive, across as well as along the flow planes and.bedding
planes of intercalated sedirnenta The contact with the sediments
lying to the southe& and up the Yukon is complicated by faulting;
spprmntly with some intarshearing, so that no sharp l i n ~between
the two series can be drawn. At the mouth of Roserefski River
these mks ara massive and the outcrops afford no evidence of their
attitude, but, an in other localities, they have been faulted. The
m g e m e n t and distribution of the p - n e
areas, flanked
.
on either side ly younger d i r n e n h derived from the p n s h n e s ,
bugan earlier easterly folding upon which has been superposed
a northerly or northeasterly structuml trend, which now predornin a b Between Marshall and Russian Mission crow faulting has
been a c i e n t t o produce p t offsets. (See P1.IV, in pocket.)
A m AND
*
rn&TrO~*
The greenstoneg and inteccalated sedimenb am the oldest rocks
in the region and represent the source of a considerable amount of
the material which makes up the Creta~cousbeds. No additional
evidence from this region as to their position in the geologic column
is at hand, and correlations must therefore be made with other near-by
regions where more information is available. Maddren' describm
similar rocks, here correlated with tho greenstones, on the north side
of the Kuskokwim, 6 milm above Ohngarnut, where there is a p d a tioe downward from tuRs througl~tl~ffaceouslimestones to pure q s talline limestones. Fossils of Artinskim or late C~rhniferousage
were obtained in the tuffaceous limestona, and it is therefore evident
that this period of geologic time was marked by the inception of thevolcanic activity which resulted in the formation af the greenstone
*
serie3.
AREAL DXBTRIBWTTOK.
Sediments of Cret~cmu~
age I E ~ Owidely distributed thrmghqut the
lower
Valley. In the Anvik-Andreafski region they appear
about the margins of areas of uplifted older rocks and doubtless occupy mnch more territory than is indicated on the geologic map (PI.
111, in pocket). They probably underlie considerable portions of the
drainage basins of Anvik, Hawk, Chvihuk, and Andreafski -rivers
and possibly that of the Golmva aIm. The rocks on the headwaters
of Bonasila Biwr ,are probnbly Cretaceow, and the sediments associated with the flows and tuffs on the Stuyahok are believed to be
of the same a g a Tuffs and flows which may be late Upper Gretam u s or early Tertiary occ~~py
considerable sreas in the Anvik,
Ronasila, and Stnyahok basins and appear B~SQalong the Yukon,
forming the hi418 dong its west bank irrrmdately below Anvik and
below the mouth of the Bonasila
The sedimentary mks m i a t a d with the greenstones near Marshall have been considerably metamorphosed but, aside f ram the secl.
o n d q metamorphic featarea develop4 in them, rn not e n t i a l I y
1Ynddrw. A. G., The mfneral m n r c e a of tbe miadle EWQlrrptm
king Ball.
Iln m a o n ) .
U. & -1.
-
-1
w
wbr:
.
b.ict-,,.
diffemnt h m the h t s m u s beds, of which they are b e l i e d to be
the metamorphosed equivalents, and with which they are mapped.
(See Pls. III and IV, in pocket.)
ZTTHOMQY AND S T R A T f C I R A l ' ~ .
+
5
e
-
The sediments of this p~riodexhibit a great diversity in lithology.
Conglomerates and fine-grained argillites represent the extremes in
M u r e , but sandstone and argdlites are tha most common rock typea
Grits are fairly common in some parts of the area, and in places are
of mnsiderable thicknes.
.
Some of the c~nglonerateappears to be bass1 and made up of
pebbles of the older metamorphic rocks, greenstones, and chert pm
dominating. Quartz pebbles and cobbles am found in these con, gfomemtesbut only in small %mount. Here and there are intrafomational: mnglomerat~a few inches in thiclmess in which rounded
white qua& pebbles form almost all the larger rmk fragments.
On account of the light color of the material forming these beds,
debris from them is much more conspicuous than thnt from other
T O C ~ R ,and they appear to be more widely distributed than is indicated by the number and width of the conglomerate beds seen in
outcropa
h the bssal prtion of the Cretaceous sediments sandstones appear
to constitub the dominant IiithoIogic type. There is, bowever, every
grsdation between the conglomerates and the sandsbnw, both in
size and in charncter of grain, and locally the grits attain considerable prominence. The individual grains of the grits are fragment8
of greenstone, chert, or other rmks, as well as quartz and feldspar in
greater or less amount. Feldspnr is found in varying arnoilnts in
almost all the sandstnnes. In mme rock phases the feldspar grains
appear ta be as numerous as those of quartz. The ferromagnesian
minerals appear in a few places, but theyare as a rule largely, if not
completely, altered to secondary minerals, Small grains of chert or
sl~teare dimemibls in thin ~ectionsof some of the mndstonea
Calcite is apparent in most sections in amounts ranging from s few
waall grains, which may represent replacement near fissures, t o
fairly large areas in which some of the calcite was pmbab!y deposited
as p i n s with other rock constituents, aIthough much of it may
represent later replacement or deposition from solution.
The h e r - p i n e d mcks comprise bdh siliceous and rrgilIaceous
'fypcs, as well as gradational phases between the two. Some of the
us rock are ~w,fine gmined and so badly altered that only
m a l l proportion of the grains, mostly quartz with some p k g h l a m
feldspars, can be readily determined. The argillamm be& show
several p*
of which &e are due to differnoas of induration
28
THE MWIK-ABDREAFSKI
REGIOK, ALAS=
and mme to differences' in comiosition. T h e least indumted beds
were called mudstone in the field. They range in thicheas from a
few inchea to several feet, and one of their most common chamcteri~tics is the occurrence of numerous elljpsoidaI nodules, from some of
which successive layers may be removed. The= nodules sre prammably of concretionary origin, although pmibly due to processes
of westhering. The more strongly indurated argillites have closely
spaced cleavage planes and break up into angular faceted bloeks, in
places forming the so-called pencil slates. True dates, which break
up into thin plates with parallel surfaces, are only occasionaliy fonnd.
It is not pogbla to make an approximation of the thicknew of the
Cretaceous rmks within this region, as no continuous mctioa from
the base to the b p of the =rim is e m d . Faulting, l~rgelyof the
normal tgpe, is common, and there ie probably much repetition of
beds in outcrops on this account. Nevertheless there are mveral
localities in which the section exposed is from 300 to 700 feet thick,
and lithologic diderences in these sections are sufficiently great to
warrantthe belief that they represent different portions of the mries.
If this Mief is correct, the minimum thickness for the Cretaceous is
~tleast 2,000 or 3 , W feet, and the maximum may lm 10,000 f&t or
mom
UICAL
'
P
F
~~
mstwa.
Mudstones or consolidated shales we the most characteristic
depmits along Anvik River. Some 02 thes shales display in a very
pronoun& manner the ellipsoidal noduIes already mentioned, The
mks are chamcteristically .gray to very dark gmy, and in many
places they have a greenish tinge. On westhemd surfaces red, yellow, and brown tones are pronounced. Fine-pined siliceous rocks,
locally cherty, occur with the mudstones
The sandstonee are not po rnassivo as t h w farther sonth, 6 to 8
inch beds between shaFy layers being the most common, although
mndstones 5 feet or more in thickness are occasiozutlly found. These
are almost universally grey with B greenish tinge, which may be
lacking, however, on some leached beds that appear cream-colored on
the surface.
Thin sections examined show a considerable amount of pIagiml~se
feldspraq of which albite is the least altered. In many mtions the
more basic feldspars are not readily recognizable on account of the
amount of decomposition they have undergone. Many of the beds are
c~lcareous. In some a large amount of the matrix is calcite, and
apparently some of the bait plagimlawe feldspars also have been
replaced by calcite, of which the lime radicle has been chiefly
.>. .
derived
..
.
from the decomposition of the feldspars.
r
A.
*
1
Above Rely Cross, and on the wast and north bsnk of the Tulran
opposite Paimiut, coarse-grsiqed clastic mks pdominah. Conglom~~,@ts,a3ldsndstonesalternatel~aUyinbeds100feet
or mom in thickness or in massive beds whose attitude and thicknm
a m not determinable from the outcrops. ArgiUi* of considerable
thickness are present here and there, but more commonl~rthe argilli ta
~~~?~~~~thinbedsorpartin~intheothermks,es+allynear
Paimiut. Most of the pebbles in the conghmerste consist of green,
black, or gray chert, but gebbles of gabbroic or basaltic m k s are
rather mmmon. The grits are essentially the =me in composition
as the conglomerates, representing s greater comminution of material
from the same source. Similar material is found in the sandstone,
of which quartz, feldspar, and chert grains am the principal constituenta All these coarser-textured rocks show on expowd sarfaces a
predominance of rounded forms, which have probably been produced by exfoliation. The rocks are all indurated, and some of the
mom quartzom sandstones might better be termed quartzites and
others grqwackes.
'She nrgilIitic mcks are gray to neady black indurated shales,
mma of which contain small amounts of carbonized material. T h e
arfillitm contain many closely spaced partings at various angles,
m that the dkbria reslrlting from their breaking down is mainly in
angular fmgments. Some of the rock that breaks down into elongated fragments is called pencil slate. True slates m not m m o n
in thisarea
noc+nlia ~ U E .
+
-
'
,w
Fine-grained rocks pdominate along the Yukon from the month
of"Mountain Creek to a point below Dogfmh VklIage. They are
largely siliceous and indude cherts and quartzites as well'as some
be-grsined quartzite8 containing a considerable amount of argillaceous or possibly tuffactmus material. Associated with the finergrained rocks are a few beds of grits and conglomeratq but the
pebbles of the conglomerates am mostly not aver an inch in diameter.
A large proportion of the pebbles are of green and horn-cdored
chert.
Jn the mnge of hills nmkh of Doflsh Village great many dacite
porphyry dikes intrade the sedimentary rocks. These dikes have
probably increased the induration in the mlicmua bed% rendering
them more resistant to erosion. than rocks in adjacent areas, 'm that
the high& peaks in the region are found within them r a h at rr
m-vdy
~bortdisbnce from the river.
30
TEPl aKVlK-hRDREAP8KI REI3IOB,
9EVlLfI ELBOW.
*
A tather 6 d e lithologic range appears in the outcrops along the
north bank of the Yukon between Grand Island and-Round Point.
Sandetones and argillite, cornparrzble to those of the Cretmmua aabove discussed, are included in the series, which contains, in d d i tion, however, msny fine-grained giliceous and argillaoeo~~
sdimenb
of somewhat different character. These sediments am thin bedded
for the most part, and in places show numerous alterations of the
two principal phases. Some of t h e beds are light colored, in places
nearly white on the weathered surfacq other beds are grean ar
brown or darker gray. Where these di flemntly colored beds occur together, ns opposite the island about 2 miles below Toklik, the apparanca of ribbon.bsnding is pronounced. Jt is probable that same of
the green bands may represent altered ash beds or tuffs. The saquence of the beds is not wholly clear, but there geem to be fairly good
structural grounds for comidering these m h younger than the
eandshnes and argilliIt was notd .in this small area of Cretaceous mks more mspjcnously than elsewhere that the exposed sections of small r i d m
that srre truncated by the river commonly show the effects of weathering an both the upstream .and downstream sides near their base&
This weathering is made canspicuons by the rusty red color of the
residual material formed by the decomposition of the hard rocks.
Decomposition has p m g t d so far that it is not always pomib1e
to determine the contact of the rocks with the overlying silts where
the entire sactian is esposed. In the mte~
of the truncated mtion8 the rocks are we~theredmrnpaml5vely little, erosion proceeding
so rapidly that it almost keeps p m with weathering.
In the a m where mining operations am being carried on near
Mafshall greemtones of various types predominakt, bnt there are
soma sedimentary rocks that are considered C f e t z ~ ~ ~ ~Their
u a . distribution is shown approximately on the geologic map (PI. In,ia
pocket). In this area sandstones and argillites have k n altered to
qusrtzita and slates, and conglomemtes C ~ Q - i nqnartz
g
pebbles haw
hen' sobjeotad to p r e m m so great that the pebbles have been
s h e a d and distorted. C R e h are interbedded with the other d i ments, both light and dark gray varieties being men either in outmop or in the gravels on Disappointment Creek.
The sediments are cut by a number of dikes and larger intrusive
bodies of acidic m k , which sra dimmed uhder the h
a :.pews
roch" (pp. 4447.)
I.:%
OWILHUK AAD -BE-
P
-rn
*
C
In the b d n s of the lower ICupkutnk, Chvilnuk, md Andreafski
rivm the csrving of the stream rnlleys has been gr;reatly facilitated
by the occurrence of an emily eroded bedrock. Both the Kuyukutuk
and the Chvilnuk flow into n slough of the yuIron after pasing for a
considerable distance through the Yukon flood plain. Similarly,
Andresfski River and its east fork flow in rather wide valleys and
join after reaching t11.e flood plain of the Yukon. It is probable that
the wide valleys of these strcams nro also dua partly to the fact that
they were f o m d when the base lemI of emion was much lower than
it is now.
Mong the route traversed the Cretaceous rocks appear for nearly
$2 miles below tlie mouth of the Ohvilnulr, and are succeeded on both
Bides of the river by Quaternary river-laid mnds and flood-plain de
paits, which extend ta the mouth of Andreafski R i ~ e r . Here the
Cretaiceous beds reappear and extend up the m ~ i nAndreafski as far
as the traverse was carried, and it' is known that they form the hills
along tba north bank of the Yukon for sveral miles below the mouth
of the Andreafski.
t same pham
. The rocks near Pilot station are slightly d i f f e ~ nin
from those seen dsewhem. Some of the beds show striking alternrttions ~f sandstone and argillite laminm Lenticular sandstone layers
appmr in the argillites. T h e argillitirmaterial is usually so nearly
black that in the talus it resembles " bloom " from a me1 seam. Some
of the gandstones are highly cakareous.
Movement slong.bedding planes has been cmnmon in this mia,
and in certain localities slickensides appear on practically all the
Mding mrftrces. In the black argillilites graphite and sericih occur
along the slickensides.
Along the Andreafski conglomerrttic phases are morecommon than
near Pilot station. They appear generally in sandston~several feet
thick, and the pebbles have a maximum diamehr of about 2 inches
Some of the pebbles are whih vein quartz, but more of them consist
'of argillitic material. The nrgiIlite pebMes Have a poor cleavage,
which has been developed sincc the formation of the mglomerates.
The argillitic rmks are mainly slaty, but they include some fossil
leaf-bearing beds that have suffered comparatively little metamorbeing mam8Iy more indurated than well-compacted shales.
Closely spaced joint cracks, however, cause the rock to break up into
angular ftrlgments and make it difimlt to obtain determinable leaf
imprints. In the sandstbnes the leaves arc represented o h y by a very
faint smear of graphite and the stems by indeterminable cornprmd
c a r b m h d rods Besides the leaves, some nf the argillitic beds also
e d i s b o r t e d casts of invertebrates, and in a few places the two
f&l typedl mmr togther. This &tion,
tagether with the alter"nation of mck types and the presence-of well-preserved f k l ripple
marb, is indicative of near-shore or shallow-water dposition.
Mawive bedding is the gensrd rde for the sandstones, grits, and
mnglomenrtas and is found in some of the argillitic rmks as well. In
some of the coarser rocks the bedding planes am not determinable,
but in the finer-pined clastic rmks slight W u m l or color differences make them apparent. In placm rr thin band of argillite appears
between heavy beds o f sandstone or grit.
Ira. conmqneoce of the deformation to which the entire series has
been subjected, jointing is practically universal, but natumlly the
joint planes am more closely spaced in the argillites than in the mndston- and grits, so that talus from the argillites is cmnpmed of mall
angular, faceted pebbles, whereas thst from the sandstones and grits
is made up of large boulders, h l l y metamorphism has been so
jntensa as to convert the argillites to slab that have a typical platy
d e a v a e mostly pacallel tm the bedding.
The sandstom show in many plnces a slight tandency t o assume
rounded forms, between joint cracks, which is attributed to exfoliation through weathering. In the argillites a somewhat similar feature may be due in part to weathering, but the exceptionally wdldeveloped ellipsoids sometimes formed are probably concretionary.
Deformation has been most severe in the vicinity of Marshall, bnt
exposures there are not suflcieet to indicate the attitude of the be&
Elsewhere sections along the Yukon and its larger tributaries afford
opportunity for dudies of the structure. The dips for the m e part
are less than 45*, but on the h a i k and on the Yukon below Toklik
beds standing vertical or having revem dips were seen. The beds
drike mainly in *,northerly or northeasterly direction, bat near the
Devila Elbow m e northwesterly strikes were measured. The older
greenstones are in geneml flanked on both sides by Chtamow wediments dipping away fiom the greenstones ar by W b l y Cretaceous
tuffs and flows, a distribution of outcrops that s u g w an anticline
w h m crest has been truncated by eroaion. Ammpa&g
minor
open folds are seen in outcrops between Akaharnvt and Ohogsrnut.
In tha group of hills north of Dogfish village there are cross folds in
which the nearly vertical beds strike almost at right angles to the
r i ~ e rand to the general trend of the formations. Year Marshall
either closre folding or faulting is indicated by the distribution of
lithologic units and the arrangement of drainage lines. It is probable that kith folding and fauIting have taken place, for the rocks
in the few ezposures nt Marshall snd at the hltiff below appm.minuh
faulted and exhibit crumpled and crenulated surfam.
t
f
t
In no part of the region do the Cretao~ou~
rocks appear rmde
formed, but except as noted a h the s t r e s m have been relieved by
the formation of open folds and by faulting, mostly of the normal
type. Zn nearly a11 outcrops fatllk along planes nearly perpen.
diculer to the bdding were observed, and although many of these
are of comparatively small throw, the mxurrenm of others having
throws ranging from several feet fo posibly several hundred feetand af numerous faults along bdding planes, which am not so
d l y apparent, is indicative of the magnitude of the st-,to
ivhieh the region has bean subjected.
F d plants were collected at mveml localities within the AnvikA n d m region, on Anvik River, on the Yukon betwwn Holy
and Paimiut and on the Andreafski about 11 milea above i b
mouth. Invertebrate fosils were found in the same bed as plant
fragmmta on Andreafski River about half a mile a b v e ita mouth
and were dso obtained near the fossil-plant locality farther upstresm. The fossil plants were examined by F.H. K n o w h a Those
from the Anvik md Yukon river localities are indeterminable. Concerning the collection from the east hank of Andreafski River 9 2
miles northeast of hdreafski he mpofts as foll~ws:
m. Phagmenta of bark and w d . Also fragments of dtmtylB8ons of two
kind& wfth littEe or no merfffnsp m e m d . I also note PoUommitea gsallceoikhg
and Faxodium sp. I am kee to m n f w that I am not able to platre
lot
~t~Bf8&0~
though
~ y , mere wonld seem to be no doubt of Ib being Gretaceon~
If It depended on the Podmm4Ew 1 should incline to ~ n itt well down in the
Cn?htwns. but the dicotyledons Indicate that It can hardly be older than
middle Cretaceou
Determinations of the invertebrate f&
h i d e , jr., ss follows:
'
were made by J.
B.
877% 16 A ~a 134, Enat bank ot AnAndrenfakl River 9 mumi -n
M
aiski t
BmalI nniw of t h m w fQur pmbablg nnd&W
@ear.
Frament of gaatrogod.
9176. 18 A Ha 1%. East bank of h d r e a f s k i River 92 mlleg nort8Andrentah1 :
Sphaerium ap.?
Unlo ap., mall f o r m llke t h m in lot Brpr4
Cionlohads sp., fragment# of a sharpkeeled form and o f a mnltffineate
form.
Vlvlmrns m.,iragmentsl of a b i g h - n m form and d a &out low9pIred
form.
h
6
.
18 h Ha 140, Weat bank of Andreafakl R l v e ~L5 mllm below A n d m u :
OH- #.+ mall nnsculptnrd form,
-sat,
apparently o f n Iargehelwypd with a
like that ai
34
-
as&
-
A W V I K - ~ ~ P ~ ~REGTOIT#
K I
ALASK&
tX1lsstEmm W74 and 9775 cwCaln the
faoi fiW~-mbsrm?leaqMs
and ;Rasrtopoda The nnios do not dWer m t l a l l g fmrn forms cdlected by
Colller, Atwood, rind Hdllck along the Ynkon a t and below Nnlato. AU are
probabb undesuibed, The aame is true of the gastropods, ggeeimena collected
by Golller, showing no appreelable dlfPerenc@a The h m p Is anppmed, on
phgafcal grounds, to be Ckk.etaceon&though in itself it does not fiord concl'nalve
evidence ot Its age, for the tgpea represented are
long range.
E . ! ~ ~ t97T6
m contains a form of Ostrao Lnsepamble &om material mU&
by Holllck near Nnlata and repre8enb a brackish-water fauna Wo such forms
are known in the Tertiary of the entlre region, and tbis l o t also is probably
Cretaceous, though the f o ~ f l salone are not sufficient p w i .
Other mllections made in 1902 by A. J. Collier,in 1903 by Arthur
Kullick, and in 1907 by W. W. Atwood and H. M. Eakin inolude
specimw obtained along the Yukon from a point near t h e mouth of
Melozitnrt River ta s point a h u t 10 miles rrbova h v i k and probably
rep&nt the aame series of rocks as those found in the Anvik-Andreafski region. The plants horn them collections were studied by
Hollick9who summarizw them as follows :
'
There in a fomplex mixture of floras, not only hrnn locality to W t y , but
alm In many of the Sncllvfdual collectlans. L~~alitiee
of Iower or mtddIe C m
taceous strau alternate with locnllHea where the beds are of Upper Cretacmns or posslbly d Tettlary age, some of them'only a few mElm 13-t
from
each other, and nome of tbe coIlettlons contain floral elemenb m dive- that
I t fsimpsstble at pment ta correlate them ~atMact@rlly
wfth m y h o r n or
described flora. There can be no doubt that the co1IectIons Pn at least two
of the localltiea indicate strata as old M lowemdddle Cretaceom ; the 0thindImte strata whlcb are either Oretamm or questlonabb t
u yoas b n d
&ten&
Marine and M - w a t m hvortebrntm from the mme region have .
been determined by Stanton to be mainly of Upper Cretaceous age.
The wide distribution in near-by regions of known Cretaceous loch
that are LithalogicalIy similar to those in this region, together with
the corroborative evidence of the fossils found, even though they
wem obtained at nther widely sep~tahdlocalities, md only those
mIlgcted on Andreafski River are of stratigraphic oalue, affords
grounds for the belief that the consalidated d i m e n t a r y scrim as a
whole is of Cretacms am 30 far as hss been determined, however, the entire Cretaceous section may be present, together with h a 1
Tertiary deposits It is not impossible that Triassic or Jumsie
mka QWW In the areas mapped as Cretaceous, but no evidence of
mch ~ g for
8 any of the rocks waa found.
Some of the e f f n ~ v erocks m Anvik River appear a intmalatad
flows,
near the top of the geriea, and are therefore late
Upper C r e ~ ~ or
u a&rly Tertiary. These flowa are bdieved &
belong to -tially
the mme period of igneous activit;y ~s the extravasation of the flows, tbe deposition 03 the tuffs ~JI &:&
basin, and psibEg the intrusion of the earlier CTO~CEOUB
sBdE
by dikes of acidic rocks.
f+
l
,f'
-
Cretaceonsrock are widely distributed elsewhem in w d m n Al-
r
-
and probably have a greahr a d extent than dl other consolidated
deposits in this general region. From the R d u k wutbaastward to
the Melodhm and southward to Nulato and Norton S o d , as well
as along the west bank of the Yukon still farther south, both h w e r
and Upper Cmtmus rocks are found. South of the Yukon tbey
crop out in an area extending from the headwaters of the Nowitna
and its tributaries to and far south of the Knskokwim, including the
lnnoko and Iditarod districts South of the Kuskokwim volcanic
appear in the series Cretaceous strata occupy considerable
the Almka Peninsula, where dimentation wm apparently
unintmrupted during the transition period from Upper Cretaceous
to early Tertiary time. Evidence of the wide distribution of the
Cretaceous rocks &where
Alaska is afforded by their presence
along the north front of the Endicott Range, in the Yukon-Tmma .
region, in the Ghitina Valley, and in southeastern Mash. Close
codation of the Crsh(380us of the Anvik-Andreafski region with
that of other regions should not yet ba attempted. It is, however,
safe to make broad correlations and to stab that the deposits of the
entire lower Yukon Valley were hid down in the same or adjmnt
basins during Cretatseons and Eocene time. A concept of the conditions of sedimenbtim in p t embayments, with alternations of
periods of quiwence, wb~dence,and &onrl
elevation of the land
surfam, sffords a means of undemhmding how mch a aeries of =la
might have been f omed.
r&
~1.eason
As
suggested above, a portion of the mdimentp mapped &B Cre-
taceous may be early Tertiary. If this is true, however, the Crehmds and Tertiary localities can be =paratad only through the
finding of determin~tivefossils, as the rocks of the two systems, if
-
both am represented, are lithologicaI1y &milarm
It is likewise possible that the seriw of tuffs and flows interca.1at.d
with the sediments at one Zwlity on Anvik R i ~ e rmay km Tertiary.
, IJCOpther with the intrusivas below Holy Crops, these m k s are considered in the-fomgoingdwription of the Cretacauus rocks, for they
are of the same age &s ~ ~ SUPPOSB~
k s b h C ~ ~ B C B O The
U & effusive
and i n d v e mlrs rare wnsidered as belmging to the same period
of igneous activity, although no direct evidence to support this inf'erenm was
No sediments hewn to 'be of Tertiary age were
''\found. It is likely that during Tertiary t h a , especially during the
liter part, the p m n t topography was outlined, although the base
levd was ~onsideFab1ylower than at p m n t snd the relief w m
W y Iterrdrial deposits were formed, and these have Geen
=.
.
'
almost, if not entirely, m o v e d by Qnatemary erosion or covered
with the prodncts of erosion.
At .two localitieg d h e n t s o ~ c n rwhich may *be of Tertiary age.
Near the mouth of the small meek entering Andreafski River h u t
200 yards below the p i t office at Andrerfski is a very -11
exposure
of blue d a y which differs from any Q u a h m r y deposits sen. On
the Yukon 24 milea above Ingmmhart grave1 beds are overlain bg
basaltic flowg, but as the pebbles of the gravel are similar in composition to the overlying flows, the presumption is that they belong ta
the same period as the Iavaa No direct evidence is at hand as to the
pohble Tertiargr age of either tlie clay or the gravels. No fossils
were fennd in either place, and the relations of these beds to other
rocks are such that they might be either Tertiary or Quatmriar~r.
They ara described in connection with the Quaternary depkti3.
I
OUATEBHAXP BEDA d E # a E B A N D PmcmBE&
<
The u ~ l i d a t s depogita
d
found in this aegion a m of many types
and owe their p m n m to different.agencies and prucem= Silk md
gravels that lie st elevations we11 above the prmmt stream camsm
undoubtedly were laid down in park as deltas in embayrnenta at a
time when much of the region was inundated. On reelemtjon of
tba land snrfsoe:,dFainaga linm were again established. It appears
likely that for the most part the muma of premnt streams am t h m
of the priod following the mIevstian. These streams have laid
down allnvial deposits of gravel, sand, and silt, the extent of which
is generally Iimited by the flood plains, sb that &longthe ma1Ier
streams the deposits are but a few feet in width, whereas along the
Yukon and its larger tributaries they extend for many milea
On the higher hi& and ridges the products of comminution by
mechanical and chemical forces form a mantle over much of the
surfam, either as. miI, as tnlus, or as broken residual rmk daris.
So completeIy do these dspsits conmal the underlying rock that
the nature of contach and the attitude of individual beda em'
obscured.
Vagetatioa s e m to
~ hide still further the ~~ of the material
upon which it grows, especially on all but the s k p & dopes in the
nntimbered areas, where lichens, mosses, and g - r make
~
up n
protective mat and in some p l a w form p t beds that may be several
inch@ thick.
Practically the m t h mgion is thns mantled with Quaternary d 6
pogita which maaH what Eiea beneath. Bedrock is as a m l e &n
only dong the Btreama and at or orthe awh of
d&aa,
.
t
w
Many af ths oukropa on hills or ridgp comr only smaU mcm and
g ~ ao
e mnch a f f a by creep or jointed by frost as b Se of little
eerlrim in the intarpretation of atfucturb
T h e Quatarnary deposits as mapped include only the-older silta
and recent slluvium, not the residual mantle of mil, talus, and m k
dQbriaor the covering sf ~ t which
,
w e not mapped, Although the
9
m
older silts and m n t alluvium are dascribed separably, they are
map# together, as suficient d a b were not obtained to map them
individually. There is not everywhere s topographic break h h e e n
. the older and younger diments, and contacts that are not exposed in
outs slong the banks of streams are masked by vegetation.
Between the higher-lying residual soil or blus on slopes and the
ailta or alluvium there i s generally no sharp line of demarcation and
apparently every stage of gradation in topographic form exista Aa
a m q u e n c e the boundary line9 as drswn between the areas of
- wstsr-laid d e p i t a and of bedrock are of n e w i t y approximations.
m
-
In the v d e p of Banasila and Anvik r i v m and at numerous
plscss on the Yukon and one locality on the Andmafski are dt and
p v d beds which lie at considerabla elevations above the p-t
streaah courses. These deposits were noted in d o n s along streams
almost 300 feet above sea lGvel, The expaam usually has tha appearance of a di-ted
terraca, doping back from the top of the
d o n at a very l o l ~angle. Above such.brrace63 and f~rkherback
from the drabage courses rise dill other t e r r a m to elevations of
&out 800 feet, in which no &ions were sen. It is significant,
bowever, that rocks crop out but rarely belov 600 feet,, except along
gtrsam mts, and that outcrops a m considerably more c a m o n above
this elevation. Section8 of the older gravels and silts are not wpee i d y w h o n , even along st-,
but q m s m e a were eeen in many
parts of the area and a E o d evidence of the widespread di~tribution
of such sediments.
At h v i k silts cover the undm1yhg bedmdq which ia exrpased only
dong the rives beach. Two miles up An* River sand and silt make
up the blnff that r i s a deeply about 100 feet above the river. Farther
npstream they appear to merge with the present fld-plain deposits
of the Anvik. About 4 or 5 miles Mow the mouth of the Beaver a
enters the Am*
from the east. For s quarter or half
mall
a mile above its month the silts form a bluE 20 ts 30 feet high, into
which the rivm _is attirig. At the upper end of the bluff bedrock is
exposad in a mnch westhkrad outcrop, which is overlain by weathered
graveh occnrriug at the, upper end grade downstream into finer
material. At tke upper end of the outcrop pmcticaUy the entire
sgction consists of gravel; a few hundred feet downstream gr;ravels
-
and sands are interbedded; still farther downstreem practically the
entire section is,b e sand m silt. On the lower Bonasila the river
cuts' against the law hills betwen Bomsila and Anvik rivers, giving
exposures of 30 feet or more of h e sands and silts. On the Anvik
aide, hills of simil~rmaterial rise sharply 150 feet or more directly
from sloughs of the Anvilt
.
. Between An* and Russian Mission the older unconsolidated deposits are seen in few exposures, but well-developed terraces $u& as
cra m i a t 4 with thee deposits elsewhere appear at .several levels.
Of these hrmca the one at 600 feet seems to be the most persistent.
Along the hill facing the river erosion has removed not only the unconsolidated sediments but bonsiderable of tha underlying bedrock,
and it is only in the mall lateral valleys that the sedimenh remain
and appear ae bmaces. Much the same conditions are found b l o w
Hussian Miion, bnt the exposures are somewhat better. In the small
slough about 2 miles below Rumian Mission at least 200 feet of silts
Ire exposed in what appears tu be an old bednock deprekon. On
either side of thi exposure silts ta a depth of several feet overlie the
bedrock,as if the old depresion has been filled to the level 'of its banks,
and dimentatitm had then continued ever both the Hied depression
and the adjacent low hills.
At several plates farther down the river essentially M ~ l a rhaturn may be m,the gravels and silts that 6ll the lateral tributaiy
vaIle~tsstill pe&jng.
Such deposits are especially xidiceable 2
mil- h l o w Toklik, where 15 to 20 feet of silt ~ n fine
d sand appear
above 50-foot exposures of the C r e t m u s mcks From the upper
edge of the silt q o s u r e te the crests of the flat-topped hills-150 to
200 feet above the-riverthe slopes are less s h p and are csvared with
regetetion. It iseems likely that these h i represent gilt terraces on
the fronts of the hills farther back from the river. Similar terraces
are wen near the Cross Slaugh but are l a distinct elslewhm, aa at
Marshall, on account of the much g d e r dope of the b e d r d .
Qn Andreafski. River terraces are only faintly indicated. The
dark-gray or blue-gray mnd and clay bank of the stream are in p l a w
1 5 to 20 feet high and possibly r e p e n t the products of flood-plain
depasition, though they may be older. The gravels smn at the end
of the Survey traverse, 8 or 10 feet thick where exposed, map also
be river borne or they nay be the basal beds of the older grave4
sand%end siltxi, but no mtiona were ob-ed
here w elmwhere on
the hdwafski of a natnre to confnrm the sugges$ion
this
- -= -5 -&to
;-$$
ocxurfenee which the brrace forms p-t.
T
-
t
-
-
.
-
Nem the mouth of the smaU stream below the warehouses of
the Northern Comnewial Co. at Andreafski is a mall outcrop of
Eight blue-gray clay. Its age and origin am wholly in doubt. It
nmg represent a remnant of late Tertiary sediments but appears
9
I
.
t
more likely to be Qnxtemary and equivalent to the older gravel~l
and silts or fo more recent river-'Saidsediments.
T h e exposure of graveh under the Aows above Ingrumhart is disc u d in oomectioe with the Quaternary igneous rock^. (See p. 49.)
The mast satisfactoq explanation of the origin of these highlying unconsolidated sediments is aflorded by the hypothesis that
nn inundation of the region covered points now 600 feet or more
*born sea level and that the gravel, sand, apd silt represent the
deposits laid down by the advancing sea and reworked by the re- .
treating sea during the period of emergence. From the oczumnce
of deeply buried valleys such as those on the lower courses of Anvik,
R o n d a , Koserefski, Kugukutuk, and Chvilnnk rivers and some of
the smaller streams it is evident that at the binning of the
period of inundation the base-level of erosion was lower and the land
stood considerably higher above the sea than at the p~>resenttime.
The record of the inundation and fillimg ia of d e p d o n s below ths
present land surface is conceal4 by the sediments laid down at that
time and by the later alluvjal deposits, If elevation and subsidence
$oak place fairly uniformly over the &ire region, as is indicated
by the presence of terraces at the same elevation a t widely seprtrated
localities, the outlies of the sea a t sum-ive stages may be closely
approximated from the topographic map (PI. I, in pocket). From
Russian Mission t o the TCuskokwirn as well as west to Bering Sea
the deltas of the Ru.skokwim and Yukon were inundated, and embaymenk reached far up these streams and their tributaries. At successive stages of the inundation deltas were fbrrned in the embayments e t the months of the &earns, and the delta deposits are now
mpresen'ted by g r a ~ dbeds such as those on the Stuyahak or on the
Anvik above the mouth of Yellow River. Beach deposits were
formed along shore lines a t about the same levels, and these msy
b r e p m n t e d by the gravels near Anvik. Fine arndn and silts were
Inid down in the deeper water of the embapments. Deposits of this
type form the plain through which the lower Stuyahok, BonasiEa,
and Anvik rivers now flow. T h e fine and unconsolidated nature of
the materiel Iacilihted the rapid cutting of the stream courses in
adjadment to new grades, and later erosion by lateral cutting has
produced wide valleys and flood plains intrenched in these older
spediment~ None of the other large streams were travemed by the
Survey party, but it seems likely from the evidence afforded by the
low terraces along tbc Yt~kmas far down as Marshnll that innn-
-
40
Tlf& ARWET-ANDItBIAPSEI REGION,
I
Ugh.
dation occurred there under the ssrne. conditiana as elmwhere. and
that similar deposits will be found in the vaIleys of Buyukutuk and
Cbilnnk rivem.
No direct evidence was found in the region as to tile' age of t b w
deposits, except that there is generally nno sharp line of demarcation between them and the products now Wng formed by w i d u d
decomposition, ssliff action, alluviation, and other pr-.
Silts and p ~ a l essentially
s
similar in character to those in the
Anvik-Andreafski region are said to be widespraad throughout the
lower Yukon and Koyuhk valleys' 'The best exposures of these
deposits along the Yukon are in the 'Palisades below Tanana and the
high ~ i l tbluffs about 8 miles below Louden telegmph station. No
such aections have been noted in the Inneko and Iditarod valleys,
although M a d d m P mentions silt bank,^ 30 feet high on the lower
hnoko, but the occurrence of 50 to 70 feet of muck above 5 to 20
feet of gravel on Ymrman.and Flat creeks, in the Ruby district,'
and of 70 feet of muck above 30 feet of gravel on Boob Creek, in the
fnnoko district, indicates that pracem other than alluviation were
active in those areas. These deposits and those on the Yukon am
attributed by the writer'toinundation, the agency that enused the
formation of the silt and gravel beds in the Anvik-Andreafski
region.
The fresh-water Pleistmne invertebrate f d l s found in the silt
a t the Palisades are prhumed to have lived in a fresh-water estuary
at an early stageofthein~ndation. Znthesillaab~eAnvikCtilmore~
collected remains of Pleistocene mammals, finding h n e s of mnmmath and bison a h t 5 miles nbove Rall Rapids, and W.C.Cham, of
h v i k , foundthelowcx jaw of Ekphmnear Grayling. Gilmore also
mentions a re@ed PIeistocene fossil Imality on the Yukon-Kuskoh i m portage. Other such locdities in the vicinity of a lake
of Andreafski and s lake near Fort Hamilton were reported ta the
writer. A I ~ r g ebone fragment seen e t Andreafski was said to have
come from the locality near old Fort Harnil;ton. The Pleistocene
rna-1
bones found by Gilrnore near Hall Rapids were similar to
othersBfound by him at the Palisades, on the Xowitna, and at other
places in the Yukon basin. Similar fossils were geen by the writer
a
Ft. M., The Yulron-fCo>nkuk region, I l a h :
8. -1.
Survey BulL .BB1. pp
1916; The Coma-Nowlton reglon: U. B. OmI. Sumey Bull. 887, pp. 35-86, 1918.
MeMs, 3. B., mud Harrlngton, O. L., Thc Enby-Krralokwlm reglon, &ash: U. % -1.
Bnmef BUIL
(In preparation). Gllmo~a.C. W., EEmlthdan m.ColL, rol. 6 1 Na
1807. 1908.
r Maddren, A. O., T h e I ~ ~ P L
sold
o placer U!lMct,, Alaaka: U, S. awl.
Slln,
110, p. 68, 1910.
rMprtie, J. a. lBd H m i l r n , a. L,rbl BElbl-K~8kokWhlreghl, u :
33. a
Wl. Rnrvey Bull.
tfa prepasatlon).
* W m o r e , C. W., op Ht., p. 12.
* .>
Gilmore, C. W.,on. elk
. *. ... 1n k i n ,
M,
-
-
7
..
v
*
t
*
on m a y bf *the meek9 in the Ruby district. This fauna mmes to
c o d a t e the Bilt in the localities where evidmce of it is found and
to furnish evidence of its Pleistocene age.
Shell fragments were also reported
having been found in 'k&
pita during the c o u m of prospecting on the flats nmr Willow C m k
These were not 'seen by the writer, but from the description given
they appear to have been marine.
7
MODERN BIUFAM DEPOBITB.
Thmghout the region the ~treamaare trarisparting and laying
down gravels, sands, and silts, representing reworked older material
of similar texture, either of alluvial or mmrine origin, ss well as soil
and other comminuted products of chemical and mechanical disinkepation. In all the streams except the Yukon the water is clear,
excapt na it is discdored by vegetable matter or, during flood s t e p ,
by ,silt and sanda. It appears likely that part of the deeper-lying
grsveh found in prospecting on some of the dreams were formed
, at an earlier time and possibly by other agencies, but further dudy
will be required to determine these-pink The creek gravels along
same of the streams near Marshall are discussed under '4Xnern1
rafwunres (pp. 694%).
In Ehe 1ower.reaches of the rivers tributary to the Yukon gradients
are low and stream veldties appear b be mntdled largely by the
rstage of water in the master dream. This feature is well displayed
by Bonasila River. On July 8, 1916, the current in this stream was
barely perceptible even a t 20 miles above the Yukon; two weeks
later, when the Yukon had fallen 6 feet or more, the current in the
Bonasila was noticeable almost to its mouth. During stages 'of
high water the silt-laden Yukon overflows its own lowlands and
those of many of it^ tributaries and deposits most of the fine
sands and ailts. As tl result the banks of the lower reaches of these
Btpeam~ are made up wholly of silt, largely deposited by the
Yukon. Farther up the tributaries the silts R ~ the
R
result of fldplain deposition by the streams themselves, and althou~hthe banka
may be 6 to 12 feet high, they usually contain sand and gravel layem
near the base, and gavel bars are normally found at bends in the
stresma Oxbow ~Ioughsand lakes, resulting from the cutting
through of meander loops, are of common occurrence in the d d
plains. Nearer their heads the stream madienlts inmeam, the, flood
plains become narrower, and the alluviaI deposits include more and
more &vels and sand.
The d m a t s laid down by the Yukon are mom &king than
-&:$he.
d e r dreams. Stages of water 30 or 40 f& &hove
A
$'
w
w
-
,
the normal are rapohd, afld for msny miles along the river tha
banks nrei not over 90 feet high. On the left bank Ad-plain deposition reachea back mveml milee from the riper, but w the right
bank the river wts bedrock at many places, BO that %&-plain
d e w i t s on this side m u&lly of small extent. The rate of deposition by the Yukon was very well shown in a cutmbank at the, edge of
a marsh near the mouth of the Bonasila. In this b m k ,thin bands
of vegetal material alternate with beds of fine sand and silt from
-a quarter of an inch to 8 inches in thickmm In a section of 3 feet
about 50 such aiIt beds appear; and as each layer of vegetal material
probably repkenh the growth of one m n , or possibly two: and
ertch layer of sedimenh represents the deposition during the p e r i d
of overflew, rmtinIy in the spring, it seems reasanable to presume
that the time required for the anmulation was approximately
60 years, or 950 years for the accumulation of the sediments represented in the 15 feet e x p m d in the cut bank. Conditions appear to
have been. exceptionally favorable for sedimentation and preqrvation from emion at this place, and it does not follow that d i m e n tation is proceeding at this p ate evexywhem in the region. At sev-,
ern1 places, however, the &amboat channelts have changed considerably in the last 15 or 20 years, the old channels having filled up so
as to be impassable to the larger boats, and sloughs have been c ~ l t
through tp form new channels. Thus Polks Slolrgh a t Mnmhall is
now used by the stsambosta and is rapidly cutting a larger channel,
while the much larger old channel is being ao rapidly -filled that
none of the steamers now follow it. Above Psimiut the main stream
formerly flowed to the north of Ham Island, but it now flows south
of tha island, and the old channel is filling. At the Devils Elbow
eimilar filling has taken place; the middle slough, formerly used by
~ e a m e m ,is no longer passable, and the large loop of the elbow is
the principal channel, although some of the largest boats pass
through C r m Slough.
Tho d i m e n b of the P&on are mainly fine sands and silts! and
little gravel is ta be found except st the mouths of m a l l stream
entering the ririver from the r i g k I=-n~fted pebble from these
gravels may bssem here and there on bars OF on the left bank of the
river. Below Do@h village some of the streams have built p v e l
deltas out into the Yukon. T h e sediments that were Tdd down h
watem flowing with coneiderable velocity consist mainly of sand, as
in the numerous bars covered at high water gnd the flood-plain sands
near the b a h of the streams. Q&
and feldspar grains are the
principaI minerals, but a few deposits contain some mica. The a n d
was tested wherever the banks were mfficiently dry and was found
ta contain =me magnetite. Below Russian Mission 41-'e
+
r
.-
amount of magnetite was seen in the slmd, and this is thought to
have c a d the local magnetic disturbance thet sE&d the needle
of the alidade cornpas.
The h e r d t y material is laid down in alack water and forma
most of the deposits in depressions away from the river, or in the
shallow dead water found in places along one bank, aa on the m t h
side below Paimiut, where mud 2 or 3 feet deep forms t h wide
beach between the s t ~ p
banks cut at high water and the water's
edge at normal and low stag@.
f
D
t
t
T
.
;
On dl but the gteepest dopa in this region tha underlying rock
or soil is copered by vegetation, for the most part moss or lichens,
although in =me places grasses and other plants predominate.
At high elevations, where there is useally fair drainage, vegetal
ammulationa are slight in amount On gentle slopes or on the
msts of rounded ridges mosses .and lichens, together with leava
and gram, form a practically continuous mantle, which is, however, generdy not more then a foot in thiclmess over any extensive
a m : On flat-bppd hills, under favorable conditions, t h w accumulatiom may reach slightly greater thicknesses. The most, extensive deposits, however, are formed along the poorly drained areas
within or slight1y above flood plain& In such situations the mnditiom for p w t h seem to ba most favorable and accurnuhtions of
peaty mahrial are common. For the most part these deposits are
formed from the same pIants as those a t higher dmations, but
g r a s s and dges and some aquatic plants occur in greater amount,
and trees that float in during high water or, growing on the deposit:
fall and form a part of it are of common occurrence. Many gection~
of these depasits a m exposed. One of the best exposures seen sppears in the bank of the Yukon above the Bonasila. Here the brown
peat is at least 5 feet thick and contaim mnny qnoe Togs, which
have been broken ofl flush with the mrface of the bank by floating
ice. (See P1. VT, B , p. 25.) The logs appear but tittle rothi. The
pest is layered, and some partings of silt or fine sans appear in it, tha
mdt o f deposition at. flocd stage8 of the river when the pelat was
being formed. No such deposits were seen on any of the tributary
streams, although well-consolidated M s of peat over a foot thick
em fairly abundant.
In the eddies of' the Yukon at high water driftwood often f oms
-piles on the-bmks which are several f& high, and in 1916 the bank
of one or two ~Ioughswere covered with logs two or three deep.
R.,-. .q W : b , a. .log wss embedded in the bank, bnt no suggaion
"
*
wss seen of.+
such piles becoming thick enough to form on alter&tion beas of E+ta It appears likely that for the most part these
logs are picked up during periods of rising w ~ t e of
r successive highwater stages, carried along for a time, and then droppad whm the
water falls.
None of the de@ts of peat appear t~ have iny present value, in
view' of the abundance of timber in tha areas where the peat ia founrt
v
*
XQHEOUB
-mxm%
Garboniferomr greenstun= occupy large a m in this region,
the rocks miatermingled with dimentary deposita and are
scribed in connection with the &ents
on pages 23-2&
but
de-
At a number of places M o w Rnsgim Mdon large dikeg or sills
and still larger b d i e s of stdcWike form have intruded the p e a -
*
.
stones and the younger sediments. Such intrnsiom adcur just above
the native villages of %h and Ohogamut. Between Spruce Creek
and the Kupkutuk there are several larger areas of d a granites,
the largest of which f o m s the core of Pilcher Mountain. The next
largest area is at the head of Willow Creek and extands from a paint
near the forb a t clsim No. 5 above Discovery almost to the crest of
,the ridge. Owbg to the covering of soil, cock dhbrh, and vegetation it was not determined whether this body L continuous wikh thom
to the west at the heads of Owl and Slope creeks and rto the east at
the head of McNeill Creek, Some of these a~reasare believed to repm t wparate intrusive rnagses and have been so mapped.
Along the bank of Pol- Slough, both at Marshall and s ehort
distnnce below..the mouth of Wilson Creek,there are some sheared
.peissoid dikelike bodies that approach quartz d i o r i k in composition, but their originid texture has been destroyed and it c a n not be
*
positively stated-whether they are of igneous m sedimentary origin.
Similar gneismid mnterisl w m seen'in the talus southwest of Pilcher
Mountfiin and on the north slope of Mount O h m i & Along the
r
edges of the intrusive masses at the heads of SIope and Owl creeks
evidence of shmfing 3s found in the m o n d s q structure which hw
been developed. Except as steted above, the taxturn and appearagce
of them mks ia esmtially granitic, with only an occasional sugges-.
tion of gneiswid stmcture.
At the end of the Survey trsversa an h v i k R i v g a
g
m
.
,
p
&
"
g
of diorite was geen, but its relation to adjacent k k s h s
#
mined. Similar rocks were seen in small areas east of Mount O h mi&, and on account of their lithologic similarity to tb quartz diorites 4the small size of the exposures, they rn mappd with the
quartz diorites and soda granite,
*
Cbnsidemble variations in mineral composition am found from
place to p l q but these are believed to be only such as are normally
to be expected. Quartz is not abundant, being usually lws in q u w
tity than the feldspam, though evqwhere present in moderate
s
amount except in the diorites The feldspars are all plagidase, of
which aligoclasle-albite appears b be the most abundant, but it is
ah& invariably sssociated with albite or with andesine, Other
m e m b of the plqgioclase serles which may be as b s i c as labradorita are d o n a l l y seen. Magnetite is usually found in mall
amownts, Apatite occurs in some of them m k s , especially in t h m
in which there are graphic intergrowths of quartz and feldspar.
Biotite is 1- common than hornblende or pyroxene. Secondary
miner* have ddeeloped s t the expense of the feldspam' and f o m magnesisn minerals and include epidote, chlorite, cdcib, and green
hornblende, which have given m& of the rocb a greenish tinge.
Th- intruaives am all yonnger than the greenstones, and soma if
not alI of them are younger than the memhrs af the wdimentary
- wries between Windy Point and M a d a l l , which have been proviaimally mapped as Cretaceouua 'Shere may thus be two swim of
igneous rocks of very similar chemical composition; on the other
hand, them is s ~ i b i G t that
y the dimentsrnentioned are early M e w
mic and that but one period of igneous activity is represented. It is
believed, however, that intrusion o c c u d during two periods, to the
earlier of which belong the gneissoid dikelik8 bodia near MarshaU
'
and the intrusive mass foming Pilcher Mountain, as well ais some
of the intrusives eastward from Mount Okumiak, and tm the later of
which are to be assigned the bodies of soda granite near Kaka and
Ohgamut, together with m e of t h m near Willow Creek, which
are believed to be contemporaneous with the dacite dikes in the Marshall district and in tha vicinity of Doghh village, as well as with
the andesite and dacite tuffs and flows farther north. As is stated below these sndesites and daoites are probably of early Tertiary age
They show little or no deformation. The f a d that some of the soda
grlsnitea are undefomed, though other rocks resembling them closely
in composition and occurring in the same ares, are much deformed,
3 .
is taken as evidmw of two periods of intrusian, the earlier of which
"",
is pCretaceoua This conclusion is mppprted by the occurrence 02
&aa-uf oligodam-andesine and pebbles of vein qnarta in the Crec
tachus sandstones and conglomerah on the'Andreaf ski. The fdd. spar+*
have been derived from a pre-Cretaceous medium-siliciq
'
roelr, such a~ a diorite or quartz diorite, and the vein quartz WEB derived from veine accompanying the intrusive, Such qnnrta veins
appesrattbeMaff below Marshall. They havemffereddefbmation
comparable in amount with that suffered by some of the diorites and
granites, and it may reamably be inferred that the veins eccoin.
pmied these intrusive&
The degree of metamorphism and the fact thnt so& of tbe C m
taceous sediments were derived from mcks of similar compmition
therefore appear to justify the a m p t i o n that some of the a d a
granites nnd the quartz diorites are pre-Cretaceous in age and may be
correlated with the late MiddIe Jurassic quartz dierites in the
Talkeetna Mountains described by Paig and Knopf and may epm-,
sant the great granodiorite intrusion w h i ~ h - o m m d
along the Pacifia
coast and along the axis of the Alaska Range ah about that t k a
Tbe later igneaus mlm north of
are basalt, -but thoae
muth and west of this point appear to be mom siliceous, dmite and
and&te dikw, h w 4 and tuffs k i n g fanad along Yukon, Stuphok,
and Bonasila rivbrs. The andmites acrmr mainly rts tuEs and flows
near the Yukon between h p i k ~ n dthe month of the K w f s k i
and as flows on the Bandla and Stuphok. In the Stuyahak basin
dad& were fodad ag glass flows in andetermined aar~ociatiomwith
~ndepite. In the sedimentary area north of Dogfish village and in
the vicinity of Marshall numerous dikes of dacite cut the older mb.
Dacite pebbles found m the bars on Andreafski R i m about 12
miles above ita molrth indicate that inhsives of this type oocnr
alm west of the Marshall district.
On ammt of their elm atio ions the decites and mdesitee
in the Stupahoh b ~ i ncouId not be mparatdy mapped, although
it is m c q n i d Zhat mrtny essential diffsrences exist between these
rock types Bath we porphyritic, but ,there is a wide range in
groundmass texturq that of some of the dacita flows being glaasp
and that of the dikes being distinctly granulstr. Between these two
sra gradational textural phascs. For the most part the andesim
are porphyritic, with microgranular g r o u n d m e
T h e andmites am dark g a y , some of them *pith a gmm t i n e
and many of them c a n not readily be distingaished h o r n ImsaIts.
It is believed, however, that ss a rub they weather in lighter colors
than the Gasalts. A lighter p y , in plaeas tinged with light green,
p.lm, MU~F,
.nd Xnopt. Adolph, Gmloglc W
c
e la the Ymtannaka m d
Tdkettna hainn, A l ~ k a U.
: 8. Geol. Elurvey Bum. 32'1.p. 20. 1907.
Brmk* h. A., me ~ ~ o p r * p hand
y geolog~nf Ala&kx:D. & Geot
46, p. 260, 10%
*
.
m,
P.pa
'
t
m
+
w
.
.F
,'
I
.
f
h characteristic of the dacite dikes, and this coloring, with their parphyritie habit, exhibiting nurnems qua& pbenenocryats, mmes to
distinguish them from other igneous mcks found in thia mgion.
In the drtcite flows the colors are also light, ranging h m very pale
yeIlow to a light rusty brown Fresh surfa p p r gmy, lacally
with a greenish tinge. Quarts pbenocqsta are more prominent
in the flows than in the dikes, especially on weathered surfam.
In mineral eompositian the dacitss appear to be the porphyritic
quivaleuta of the soda granites. T h e most common feldspar js
aligoclam, but there is a range from albite-oligoclase to andesiae. Pyroxene ghenocrgsts sre prominent on fmhly broken mrrfacan
Under the microscope magnetite is usually found in small grains.
Biotita appears in a few places. Secondary alteration p d n c t a
include epidote, chlorite, green hornblende, and mlcite, together with
sericita fmm the altaration of feldspam Andesine, augite, and
magnetite are the chief constituents af the mdesitw except that
some contain also numerous grains of olivine, which show a strong
tendency to weather to serpentine. Otherwise the secondary mineds
are the same as t h w produced by the weathering of the d a c i h .
It is not possible to make dehite statements as to the age of
the dacik and andasitm, which are held to be of the same nge as
the d a granites. There are, however, two points of referenThe dacites have cut the Cretaceoue rock and the andesib are cut
by the basalt dikes, so that if, as has been assumed, the dacites and
andesltes are of the mme age, they were formed sometime betwaen
the end of Cretaceou~pedimentation and the extravasation of the
baaalts, which probably occurred in late Tertiary or early Quaternary time,
Similar rocks, to which a Tertiary a& has been awigned, m u r
in the Ruby-Kusbkwim region,' and it is believed that they repregent s phase of the Tertiary igneous activity which prevailed over
western and mathwestern Alaska and are to be correlsted with the
and&& and dacitas of the Anvik-Andreafski region.
Basaltic flows appear in the low Mn8s near Rudan Miiasinn and
overlie b w l t i c grave1e in the still lower banks a t end above Ingmm, hart. The hills b e t m ~ nIngsurnhart and Engineer Creek consid
\of b a , and it is probable-that other low hiIIs between Engineer Creek
W,BltEasian Miasion me made up of a continuation qf t h a same
W a r t i e , E. B+jt. and Brrrlnstan, (3. L, Tbu Bnby-Euukokutm -om:
sripr;lP1L;rL.
-pre&mmtlOIl).
U. &
Eeot
flows. , h l t dower occupy. the m s I l area mapped on the WE& bank
of Bonasila R h , and bamlt dikes and silIs cut the andeaitic tuffs
along the Y s l b below the mouth of the Bonasila #OnAnvik River
mme basalt dikes, flows, and tuffs:are awmiated with the sedimentmy
mb. In one exposure an argillite bed lies betwmn two flows. The
'most extensive areas of them mch are found below the month of
Goblet C m k and above the mouth of Yellow Riveq d in these
areas the basal& appear to consist of a m r k af successive flows, with
which mme sedimentary rocks occur in unknown association. Basalt
dikes, sills, and tuffs occupy some smaller a r e q most of whi@ m
indicated on the geologic map.
A large proportion ~f the basalt flows are &cuZar,
but they show
a wide variation ki the amount of cell space. Some a m fairly dense,
with vsaicles few and smell; others are extremely porou& Some of
the flows am blmygddoidal. A number of the d i k a m n sbo~kIna m h a r t $re vesicular; others 4 or 6 feet thick are mare dense and
display mlumna~
structnna These dikm probably represent the vents
thmugh which the latest dravasations took place. At the lower
end of this exposnre the flow rest upon gravels which range from
cream-colored to rusty red The pebbles are basalt m d represent the
produets of ad intedow period of erwim.
The feldspam are mostly labradorite, aEthougb in some specimens
thst contain bege phenmqsts md msrnallcr laths m e of these laths
are andesine or andesine-labr~dorita,and these nppear ta represent
m k a htermediats in ntmposition between tha typiaal-basalts and
the pyroxene andasihs, Augite is the most common of the m d c
minerals, but in places .olivine is conspimeuous and here and there it:
to serpmtinous aggreg~tes. In weatheted m k chlorite is developed. Magnetite ie universally present. Some flows are a m y g
daloidal md:the cavity filling consists largely of calcite, but some
opaline quartz was alm notd.
.
-
It is not impos9ible that more than one period of volcanie s&viv
is r e p m n t d by these rocks. Only along the Yukon do the exposfford an indication of their relative aga Elsewhere the relatiom are obscure and give little additional data b d n g on this
point.
There appeam to be an intedtim of flows and sediments on
Anvik River, where; the sedimenks are p r e a b l y of lab ~rekerwuag
or early Tertiary age. Above Holy Crosa ithe undeformed basalt
dikes and silEB are intrusive in andesitic tuffs that am bshbe
I
-
af Tertiav
L
#
age. From these relatione the maximum ege of &a
appears to b late Cretacmws or early 'hrkiary. At and beIow Rnssian Mission the flows am nearly horizontal (Pl. VI,A, p. H)
md undefomed, and their attitude indicates that they, a8 asdl aa the
dikes above Holy Cross, have not been influenced by the deformstion that probably marked the end af the E m e epoch. They
have not been subjected to any Iwsl warping rtnd &ow no hulting
or folding.
Although it ia rec.og&md that other explanations are possible,
the gravels between. the flows above Ingrumhart seem best accounted
for by. the hypothesis that they mpreecnt beach gravels laid down
at a stage of the Quabrnaq inundation and subsequently covered
by flows that wem poured out during this stage. Some evidence
as k~the character of the flows ie aflorded by irregularly rounded
weathemd lava d a o e s at the level of the present river beach a
few handred yards upstream, s n g p t i n g the ellipsoids pwduced by
submarine flows. These rounded surfaces may have been produced
by other agencies, however, so thny afford no positive proof of the
littoral origin of the flow&
More definite evidence is at hand regarding the minimum age of the
basalts, which in a few lwalities are overlain by a mantle of Quaternary silts and are therefore older than the silk
Ebwhere in western Maskr similar rocks are rather widely dintribnted. Collier's unpublished notes on the geology dong the Yukon
contain many references to b~saltictuds, dikes, and flows between
Keltag and Holy Cross. Smith and Ealrin ' state that the vesicdsr
lavas of the Reindeer HiDs and Resboro Island " probably mark a
connecting link between the well-known volcanic Bows of St. Michael
on the south and of the Royuk VaIley on the northn MoEt "describes considerable areas of besalts on Seward Peninsula in the valleys of Kuzitrin, Noxapaga, and Koyuk rivers. Some of these flows
show very fresh ropy surfaces, which have been only slightly a%ded
by weathering. The age of the youngest effusives is considerad t o
be Plei;stoaene or Iste I'Jimene, but that of the older flow5 is mom
doubtful, because the age of the young& sedimentary mks, upon
which they rest, has not been determined.
It thus appears that volcanic activity extending over s considerable period of time has occurred not only in the Anvik-Andreafski
region but in other regions farther north. The evidence at hand
rshaws that sum of the eruptions were separated by considerable
intervals ?f erosion, yet it seems unlikely that in any one locality
*- aamfth, P. S., and n k i n , m. M., d *eoIagit meonnalr~nmIn sonthenatern Eewnrd
.*
Peninnula and the Norton Bar-Nalata W o n . Alanka: U. & Gml. Borvey &If.
1911.
'b-
if.. Tbo Bmlrhslrew gold placen, Btwud P e n f n w A I g e h :
Rn11. 247, pp. Sl-95, 1608.
t920Pn-l&Bon. g8s--J
449,
V. &
a 7%
-1,
-
50
THE ATTVIK-ABDEUEAFS~BEQIOX, -A
volcnnic activity occurred even spasmdieally throughout the period
between tZle tim&s of extravvasation of the oldest and youngest Iavas.
Mom probably En each locality volcanic activity wss confined to a
relatively short period and therefore was not exactly wnchmnous
with the activity at other centem.
Criteria are lacking a t most of the localities to determine the time
at which the lavas were extruded, and it is only pmsibb ta say that
although they may have h n extruded in late Cretaceous, Tertiary,
or Quaternary time it appears probable that most of them am l a b
Tertiary or early Quatemargf,
.
I
*
Too many fa& are missing to permit the writing of the complete
geologic history of this mgion. Fossils give only a -1e
point of
reference upon which an outline may be drawn, and all other hbtorical data mast be obtained from lihho4ogic relations, from the
structure, and f r m the amount of metamorphism of the rockz within
the region, or, if these facts are lacking, by correlation with formations outside the region. Nevertheless, an attampt is here made to
summarize such points sa a m known or may be s u m i d from the
aludiee that have been m d e in this and =-by p d of A l h
Nothing i~ hmof the history of this region prior to late Carboniferous tima At that tima a t l& a portion of the region was a
land surface upon which flaws were p o u d out, while in the near-by
rnsrine basins were laid down deposits coIwj$y of tnfls,
which in places alternate with eonglomerstes, sandstones, and even
argillitic rocks. These dqosite afford an indication of the changing
relations of land and rn areas while sedimentation wss going m.
In other portions of Alaska a crusts1 movement took plam at the
beginning of the Permian epoch, and the pre-Chbmus movement
in t b region may wen have occurred rrt the &me time. The result
of this movement was a g e n e 4 mt-west stmctaral trend which i~
indicated by the general trend of the p n s t o n e areas.
The axtent of the Permian .omgenic movements is in doubt, but in
the absence of known Triassic or Jurassic sediments it s%ems likely
that they p r o d u d ranges of considerable elevation.
Through early Mesozoic time destructimal procesw w e p active,
Periods during which there ware extensive movements, accompanied
by granitic intrwions, alternated with periods of quiescence in which
erosional agencies were active in reducing the land surfC
'Bmow
H.. op. dt. P
m
9
B
I
i
-
*
lwd. Neither marine nor termstrid da@ts of early Mwrwmic age
are knbwn, w that if such depsits wem formed they have h e n
destroyed by erosion. At the beginning of the Lower. Cretaceous
e w h this part of Ahska was a land surface of modemb relief,
acrogs which many broad valleys extended in a general easterly or
norkheaster1;y direction. In wme of these valleys in adjacent regions
subsidence had occurred and marine dimefits were being laid down.
Between the Lower and Upper Cretaceous epoch extensive d i a s h ghism occurced, resulting in some folding of the earlier mdimenb
and in the Anvik-Andredskiregion in the formation of depxesaions
or embayments in which sedimentation took place, It is inconaivable that the submergence of the lowlands waa cstastrophic, for the
amount and texture of the material contained in the Upper Cretaceous dirnents preclude anything but s near-b SOD
for much
of it, md the orxurrence of ripple marks, cross-bedded sandsitones,
and fresh and brackish water fauna, locally in close association with
a fd
flora, indicate littoral and estuarine conditions of depositin
wer much of the region. The almost universal occurrence of conglwnwta dong the wnhct with older mks is similarly indicative
of a sea that slowly encroached upon the land area. Periods of
qui-ce
or even of slight emergence alternated with the periods
of sumsihce, and thus were formed the basins in which a rank
vegetation flmrished and was prmervd to be converted into beds of
coal. These conditions persisted until l a b Cretaceous or early
Emne time. Sedimentation wis then i n h u p t e a by igneons activity, but the d i m e n t s of normal types that are in places intercalated with the basaltic flaws and breceiaa indicah that the volcanism was noh everywhere continuous. In other places there were
mountain-forming movements which resulted in great deformation
of the Cwtrtceous beds and superposed a second deformation and
e r n folding apon the older rocks. With this great diastrophic
moveanent was associated the intrusion of many dikes and larger
mam of soda granite along lines of weah-.
Auriferous mineralization attended the intrusion. Before the movements ceased, probaHy in Eocene1 or early Miocene time, the earlier flows had also h
subjected to wme deformation.
QUA!KRl%HARPPEBfOD.
J
A rather complex seriss of e v m h marks Che his to^ of the region
daring Quaternary time. At the beginning of this perid the surface d m d at a somewhat higher elevation than now, and the barnlevel of emion was lower, so that many of the s t r e w were able to
mrv~_deeper
valleys in bedrock than those they now occupy. It
..
c,
F?.'
'Bds, b
a,. op a,
p 2BB
-
appears likely that the stream systems had b&me well established
and a fairly mtum topography had b& developed.
At mme time h this-step of erosion there was an extmvwtioa of
b a d t i c hva which materially altered the m u m of soma of the
larger stream4 po~iblyinclnding the Yukon itself or it9 predece
sox. Such is the interpretation of the occurrence of flows Between
&&an
Mimion and Ingrumhart.
That the period of sxtrusion of the lams was 1% it3 made
manif& by the murrence above Ingrumhart of an. alternation of
flaws and of gruvd beds in which the pebbles consist of basalt derived from the flows. The gravels nay be either river borne w of
mapine origin. If the former, mature topographic forma may have
been developed at this stage ;if the latter, they mark the beginning
of the a c c e d i n g &age in the cycle of events, when them was a subaidenm of the b d surface of at least 600 feet and possibly much
more. It is i m p s i b l e to &ate how much higher than its p m n t
elevation the land etood at the beginning of the period of subsidence, but that at the end of this period the w a mupied a position
600 feet or more above its present level is dearly indicated by the
nave-cut termma occurring at this elevation, a d the unoomlidated
depasits below it.
It is believed that this inundation progmmed rather steadiIy and
that emergence fn>m the aea was almost equally continuous, h to
the duration of this period of inundation little field evidence waa
found, except in so far as the extefit of the terraces then developed
is a marker of the length of time taken to form them. These terraces are not mderrsive anywhere along the Yukon, although tram
of them a t 600 feet appear more or 1- clearly 0s almost every
ridge that risea above this elevation, and lower benches of less extent are occasionally seen. O n the Anvik M o w the mouth of Yellow
River their best development appears to be between 400 and 500
feet. On the lower half of the Stuyahok ths most conspicuous
bench appears between 300 and 400 feet. On both the Anvik and the
Stuyabok the 600-footterrace is not so gmnounced, although it may
t~ noted on some ridges. (See P1. I, in pocket.)
To this subrne-ce
are due the d n o h g of the low& portions
of prmtimlly all the valleys and the formation of the delta deposits
which stre found throughout the Pegioa,
The lack of corrolmrati~efossil evidence as to marine inundation
is t o be accounted'for mainly by two facts. Brackish-w&ar invert+
bra& whom structure favors fwilieation are few in nurnhr and,
like marine species, might find difficulty in migrating to keep pace
with fie inundation. n e conditions which have prevailed through-
1
1
-
"
-
F
w
out most of the deposih since emerpm hava t R n M to destroy
rather than to preserve evidence of animal lifa &&rznation of
the b3rpothesis of marine inundation during Quaternary time is
thmfom to be sought dram physiographic details, rather than fforn
foasil epidetlce.
Emergence after this inundation probably tmk place very slowIyF
although it went on at a fairly uniform rate, for few terra- remain
to mark stages a t which there may have been a long-continued cematioh o f movement. During the p r i d of emergence there was more
F
t
'
J
or less reworking of the unconmlidated sediments above and dong
She dmnd line, and the finer material was carried to snamsively
lower levels. The depressions formerIy occupied by the stream were
thus gradually filled with silts and fine sand&, while the higher
portions,of the former land surfaca were again ex@.
During the later part of the Quaternary period there has h n
little if any relative change of level. The most important gmlogic
event of which evidence is afforded by the plresent tupopphic forms
is stream adjustment to the new base-level of erosion, through the
m o v a l and redeposition of the earlier Quaternary sediments.
Some of the details of adjustment are worthy of note, as they
may throw light on the f o m of @ble
placers in the larger
stream& K,eeping pa@ with the reelevation of the land surface
t o approximately its present psition, the larger streams rapidly
cut channeIs.in the unconsolidated silts m d fine sand in adjustment to the new base-lavd of erosion. This base-level was then pmbably considerably lower than a t preent, for the Yukon, like other
large rivers, h d s to aggrade in its lower courw and has raised ib
own bmlevel of erosion and that of its tributaries. The tribu1taries in turn have filled in their channels in adjwdment to the p d uaUy rising base-level.
Where the streams flowed through unmmlidated materid the
gradients we& low, but in their .headward portions, a h v e the level
of inundation, gradients had besn established in b d w k in adjn*
ment to a lower base-level before inundation and were accordingly
much steeper. In conquence there was a distinct change in grade
where the stre.ms left their b d d mum^^ and flowed m o s s the
silk Emion has tended and is -ding to restore normal grades
throughout their mursa, but there still appear to be some &reams
in which complete adjument has not yet Been reached. Xn their
lower courses erasion consists of a minor amount of lateral cutting
of the high silt banks and khe migration of m n d e ~ . In their
upper reach* where erosion is most active, the elevation of baselevel hsa prohbly m u d no difference in the type of cutting going
.@3h%mghthe amount has been decreased.
howevm, has b h n place at the points wheze the
A ~raat
d r a m s left bedmk to flow in channels in the silts. Became of the
cbange of grade e t t h a p i n t s gravels were deposited there; dem & g the grade above bnC increasing it below and permitting the
transfer of grlaveb farther and farther down8tream. In this way
there have berm built up within the d t a gravel-bottomed channels
over which the streams now flow.
Many factors have entered into the lmtion of the pment conm
of the Yukon. A striking feature is the lack of hills on the.left
h k , and their presence, except where tributaries enter, on the right
bank This feature ha@been noticed on many northern rivers and is
explained by E&n as being due to deflection to the right mused
by the earth's mtation. As the Yukon is an aggrading &ream, its
channel is constantly changing, and it swings back and forth across
its flood pl~in,bnt nevertheless the emion on the right bank is
distinctly apparent and appears to mntrol the mum of t b river.
Mmy channel c h m p have m r r e d in the la& 20 yesw. Poltes
Slough has been d as the * m b t channel for only a few peRw,
and only in the last year or two have some of tha large boata u d
Crom Slough instead of the channel around the Devils Elbow. Other
changes have occurred near Holy Cross and eIsewhere. At the Bite
of old Anvik, I miles above h v i k , there is a distance of about 125 .
feet between &an and Anvik rivers, and.this distance is constantlg decreasing, as both fivers are now cutting a t this point. In
1916 the cutting amounted to nearly 24 feet, so that appsrently the
remaining narrow neck wiU be cut thrwgh in a comparatively short
bme and the mouth of the Anvik will be rrt this pint rather than
a t h v i k . At Holy Chm a h the amount of cntting may be di-17
measured, fn 1916 it-is said k t have k n 30 feet, and in'
pmvjow years it had been as much or more, necessitating the moving of many of tbe buildings that wew n a r the water fronL On
the other hand, deposition tippears td be going on a t Russian Misr
mon, although it Liea just below one of the -west
stretches of
r
-
d
the river.
& of the peculiar erosion f e n t ~ ~wan
m dong t& Yukon is the
of numems mall eemicifcular embaymenfs in the shore
rmes, in which t m stin stand but ara partly submerged. This is
well illustrakd in Plate V, A (p. 221;only the tops of the t m in the
cenhr are visible, and t h m on eieher aide am topplbg into the watm.
&law Holy Cross thew embapents are especially numerous. They
ran* in radius Zram a few feet up to about 100 feet. They have
probably bean formed by the undercutting of eddiaa at st*ges of high
u r n ot the s ~ * rststlon
m
upom tbe h t e m ~ - z - i ~
*-,
a
-:
..
Jm.Gsologg,
vd. 1%W.486--H7, 18f0.
F
e
wster'in the spring. && and f mt prevent erosion at the surf rice
but do uot prevent undermining, and as the water mbsides the entire
mdwmiaed area drops and is partly submerged. Each of thwa areas
is comparatively m a l l , but in the aggregate the amount must be large
and represents a m d e of stream erosion which must be considered.
At elevations above the direct influence of stream erosion other
p
m have bemi active.. Weathering is hastened by the cornminution produced by great variations in temperature and by the extremely effective work of frost The transporting agent *at carries
,
most of the material produced in this way to the lower leveb where
it is reworked by the streams, is solifluction rather than running
Solifluckion on sZoping surfnces is
waterJ as in warmer dimataccompIished by the heave and thrust of frost and by gravity, rwulting in the characteristic hllIside forms that show lobate waves and
from a distance have the appearance of flows of some extremely viscous substance. For the mast part these lobate forms are characteristic where t h e rock detritus is fairly h e . Where the frost-riven
rock breaks into large angular boulders, mlifluctian produces distinct
topographic farms called altiplanation terracea by Eakin: who has
described the p r w m by which they, originate. They resemble
wave-cut terraces in outline (see P1. V, 31, and may not be readily
distinguished fm~ u c hterraces a t a distance, but mmfuI mapping
(PI. I ) reveaIs the h c t that teron adjacent ridges me slot at the
srtrns elevntions and are separated by different intermla Furthermow many of them have the appearance of having been tilked, and a
terrace may be t i h d in the opposite direction €0 one below it, thus
precluding tha hypothesis that they are wave at.A lack of waterworn pebblw on the terraws also slrpports the inference that they
originated in some way other than by water action.
*
These .terraces are very conspicuous in most of the a m of igneous
rocb and in some areas of the sedimentary mh. Their formation
appears to b favorsd by mrtain conditions of vegetal growth, for so
.far as known they da not appear below timber line, dthough, as in
the 6cinit;g of Marshall, they exhnd down very dose to it. Soliflactioa prooesa%s may have acted upon land forms resulting from inundation, which, it has been assumed, extended to an elevation of about
600 feet above present sea level, but no clear evidence of this is at
hand.
The p-t
topographic forms are the resultant of all the forces
which have been at work to caws them, and it is largely through
these forms rthrt the Quaternary history of the region l
m been inter-.
preted. Each force has acted and is acting to produce definite forms,
but such
forms hsva been modified by many other forces, and the
. .
-.
t$r'ldn. H. M., The Puton-liclyakah re~lon. Alaska: U, 8. Eeol. survey Bdl. W,
W. 7&82, 1CllB.
p-t
o o n f i g d o n of the lard mrrhce hm been produced by the
agencies which haw been decribed. Erasion has been the dominut
factor, and the effects of sedimentation are only IocaL
OR the discov~rjrof p l d at D a w m and at Nome thew was an
influx of prospectom, who left few of the readily a ~ i b l creeks
e
anywhere in Alaska unprospect&. Yukon River was the main highway for these men from one camp to another and from the upper
river points to St. Michael and Nome. The Anvik portage geve a
rshorter route to St. Michael than the Yukon and was faIlowed by
some. Naturally enough, too, the bars on the Anvik were panned ,
Colors of gold were found but app~rentlynever in sufficient quantity to warrant mining, and the prospectors wught other lmlitiez
to work. Almost every year, however, there has been some one prospecting on the Anvik, the Andreaf~ki,and streams between these
rivers, In part the pro~pmtorswere men who devoted most of their
time to tr~pping,but other8 had a grubstake suficient to permit them
to devote their entire attention to the seamh for gold. As a result of
their work gold has been found in several places. O n the Anvik
there are mid to be depmits along bars cantajning gold in paying
quantities, but up to 1016 no eRort has been made to mine it. &Id
colors are said to be obtainable. in panning on Stuyahok, Kake,
Kuyukutuk, and Andreafski rivers and Mountain Creek, as well as
on soma of the mall, creeks .emptying into the Yukon near Tuckem
Point, No mining has been done on them streams.
Tha outcrop of metamorphic rock on Polkas Slough, at the present
town of Marshall, waa noticed by some of the early traders and prospectors on the Yukon, and some desultory prospecting was done an
Wilson Creek and on streams flowing into the IZupukutuk. It was
not until July 15,1913, however, that gold was dimovered on Wilson
C h e k by E. L Mack and Joe Mills. Claims were *ked by them
men, and R few days later others were located by Andrew Edgar and
A. 6.Rohde. A stampede followed, and Wilson Creek and jts tribubrim were qiriclcly covered with claim lccdiona h t e earners were
foroed. to cross the divide and located claims on Willow Creek and
other tributaries of Spruce Creek
The claims had to be recorded at St.Michasl, so that many of
them were unrecorded and titla to them; was lost. On October 24
1913, a miners' meeting was held and G. M.Pilcher was elected local
rworder: but until t h e Wade Hampton mining precinct +as &ablished, with the recorder*^ office e t M a d a l l , it a p p a d - & b & d e
m
.
W
P
to msny to make their titles mxm by recording both with the local
recorder and a t St.Michael.
Asseswent work for 1913 was not done on many of the claim
lying outside of the W i h n Creek valley, and titla to them was lost.
Prospecting during the winter of 1919 and mining operations early
in 1914 gave proof of t h ~
presence of gold in paying m o u n t 8 on
W i h n Creek. This stimulated prospecting an other streams near
by and led to the discovery of gold on Willow Creek by W. C.
Blanker, Ben Blanker, and Robert Barr. Dimvery claim, the
Bumblebee (corresponding t o "No. 1 below"), and "NO.2 below"
were staked June 17, 1914. Assemnent work and mme prospecting
WRS done on thesa and other claims or1 Willow Creek, but no gold
,.was obtained from them in 1914.
T h e shortness of WiUm Creek made it at onm apparent that the
m u m of gold in the placers was not far distant. Vein quartz
carrying free gold waa found in the talus on the east slope of the
valley about even with c l a i m Nos. 5 and 6 above DFsmvery, lu~d
the veins from which this talus came were eteked as lode claims by
Thomas Plunkett August 8, 1914.
The find production of placer gold was mrde in 1924, when about
$15,000 was obtained from two properties on W h n . a n d Disappointment creeks. In 1915 the output was a h t $25,000, mostly from .
two claims on these creeks, but the li* of producers also includes
four claims on Willow. A m a l l sample shipment of ore was also
made' from the lode claims on Willow Creek. In 2916 the gold
pmdnction was $270,000 from two' claims in the Wilsan Creek
bmin and h m seven claims on Willow Creek Preliminary estimates give the production in 1917 as $495,000, practically all fmm
six claims on Willow Creek
*he boundaries of the Wade Hnmptori mining precinct are d e h d
es beginning at a point on Bering Sea betwean Pastof Bay and
Yukon River and foUawing the height of land, which separa*
Yukon River and Bering Sea drainage, to the one hundred snd sixtyfirst meridian, thence south to a point within 5 661s of the Ku$kokwim, thencs paralleling the Kaskokwim & a distance of 5 mila.
. from it to the sixtieth degree of north latitude, thence foJIowing this
p a d e l to Bering See, thence along the coast of Bering S m , iadudk g the adjecent islands, back tm the point of beginning.
"
a
I
.
.I
s
.
'
Timber is fairly plentiful for such mining operatiom as hwe bean
conducted. On Elephant md Disappointment creeks fuel could be
pmwwmi far a time from the bottom of the valleys along thm
~
.
streama E M v e opemtiws, nsing &am power, w d d nmbte
hading wood from the valley of Wilson Creek. AIders are the only
tmw found on Willow C m k above claim No. 2 below Discovery*and
conquently all the fuel wid far producing power is obtained from
the gentle foot slope between Spruce Creek and the hillsllsThis wmd
cwts $5 a cord to cut, snd by the time it is laid down st the mine
plant d y to um there ia an additional charge of $5 to $7 for labor
and hauling.
Wagea are abut the same in this regin m at other interior Alaska
points. Minem wem paid $5 a day and board in 1916, but in 1917
this w s s i o c d to $6 and h r d ; hoistmen, bZIIWthS, and mka
receive $7 and h r d . Two ahifta of eight horn are employed by
the larger plants, but the maller plants work only one shift,. In
1916 employment wlls given to everyone who wished to work when
them wwaa a
duicehead of wahr. Nativm are employed m n d
the camp bult do no mining, They are paid $2 to $3 a day. .
The emnp an Willow Creak is very accmible. About 3 miles from
the camp, Spruca Creek Rows into a small l&4 which ernptiw
through a dough into the Yukon and rises and fdls with that
stream. Supplias may be brought t o tbe landing on the lake by
gasoline basta or fn wows, and one, of the smaller steamboats also
brought o b a r g ~load of lumber up to the lake. Tbe f&lght rate
from Mmhall ho the lmding, about 8 miles by bod, is $15 a ton.
E h r n the landing the rate in 1916 was $30 a ton to the lower daims
on the creek and $40 a ton t o points afl far up as '' NoO5 a h a n The
wintar rsta is prokbly much lower. T h e rate on general merchandise from Seattle to Marshall, by way of St. Michael, was $45.50 a
ha
In 1914 on aaqunt of traffic conditions, there wss a d t y of
-a
mmmoditiea at M a d a l l . T h e following prim were peid 'for
gtsples on the creek:
PSonr
----per budredwetght- $lo* 00
B a c o n,,,,-,1---------,------------r
pound-.3T
~ffee,---~-------------,--,,,,,,,-,,,,,-do-,,,
.75
1.00
-t2
%---l-r----------*---------------dI---do-,
Bean~,,-,,,------~----------------,-,,,,-,-,do-,
Rice--------.--11-m--------.r----------d-----do,"-,
~pr,,,,,,-,,-l--l---,,,-----------------lrlldo-,
Bn~er----h,----------,,,----------.h-------k-do
Relndeer meat ,,----l,,l-.
-,-,,,,,,,----,-,-do,,,
Bef,-,l,--,----r-r------r-------~---~r~~"~-----dO
Potatoes-,*,-,---+-----,-,------,--*-------,,-d0,-,
-123
-134
-674
!M-, 30
.
.46-.m
.o?*
Lumber was dificult to obtain until a barge lmd was brought down
-.
h m Ruby. This mld at $80 a thawnd at the l a k -..:
m*;
. .
+
until the summer of 1916 most of the mining in the hcinitjr of
Ifamhall had been done on Wilson Chwk and its tribntariea h the
spring of 1916 8 mall damp was taken out on Elephant Craek, and
early in the surnmes considerable ground was worked at the mouth
of D i p p i n k m e n t Creak, At the time of the writer's visit, about
the middle of August, there wlss no o m working in the W i n Creek
S
*
e
baerin.
Mining had been dona by mderpnnd methodrc on claim '' No.6
above'' on Elephant Creak, although the p h n d is comparatively
ehshallow. It is nnderstood that a hydranlic plant is to be instdIed,
the water ta be obtained from the headwaters of this stream. The
g m d on claim abovo and below No. 5 will be dripped and mined
by hydraulic methds.
T h e workings on W i h n and Dimppointment creeks have been
aonhed to about two claims at the mouth of the'lattsr, over a maximum width of about 800 feet, The gravels containing gold in quantities sufficient to justify mining appear to have bean irregularly diatributad, ss work was dons at several spots s e p m t d by unw6rked
'
*
a
.
ground. Open-cut methods were employed. These deposits are apparently not over 10 or 12 feet deep to M d The upper portion is
composed of 2 to 3 feet of c oil and vegetable matter, and this with
mme of the underlying p v e l was stripped oft by groundslnicing.
The lower h t u m of grvel containing the gold was shoveled into
sluice box= Tt is said that boles sunk fit the month of Disappointmmt Creek failed to m c h bedrock at a depthof 35 feet. They were
then abandoned on gccount of water coming i
a No mining has been
done in the deeper graveh of Wilson Creek itslf.
The principal mineral found in the concentrates is hematite, prabably coming from a band farther up the-creek, which is believed to
be the weathered outcmp of a pgritimd sedirnentay bed. In addt
'Lion a small w u n t of magnetite occurs in the odahedrrtl form
characteristic of tks mineral. A apecimen of a few grains+ofa whita
metal from the creek sent to the Survey for determination wm found
to be; platinum.
The bed&
is' of mdimentary origin. It was not ssen in the
cmk bad, but dates and conglomeratq together with fine ~ t s ,
appear along the muth'bank of W i l m C m k just above Disappointr
+h&~k..Craek,
and these d s , together with some dark-gkP cherh,
make up most of the gravels. Some pebbles are derived from dikes
tht wk the s~adimentargr d a and form the igneous m k s at the;
liead of the creek. The gravels are mostly small and well-rounded
pebbles, 8 in&m being about the average dim& of the largest
cobMes seen. The finer material of the graveIs is partly fbrmginous,
~ n d dthough
,
it disintegrates readily in the daice boxes, on exposure to the alr it hardens and cements the larger pebbles into a conglomerate.
WILZlOw
-
Willow Creek heads against Dieappointment Creek, and the divide
is n b u t '100 or 800 feet in elevation above the claims an which most
of the mining has been dona Mining bas been confined to the weat
fork of the c m k and to the claims from No. 2 below to No. 5 above
Dismvery ;the latter claim covers some ground on the western branch
of the small forb near the head of this stream Some prospecting
hna been done on " NO.6 above " and on other claims bdow '' No. 2
below," but in 1918 development had not progressed suffici~ntlyto
~ a r r m tthe undedaking of mining operations. Prospecting on
claims below " No. 2 below " during the spring and summer of 1917
is said to haw resulted in the discovery of depmits rich enough to
wort
TWO -11
p ~ s were
a
operating on NO.6 a b v q w the mateha1
being shoveled into sluice box= Prospecking was being done on Urn
3 and 4 above D h v e r y , and some mining waa done on them claim
in 1917. Power plants were working on UNo. 2 abovq" the upper
half of UBo. 1 above,* and the upper half of Discoveq. On Nw. 1
and 2 ~ b o v eDiscovery the avriferona e v e 1 is wheeled in barrows tO
a bucket and then h o W to l h m of sluice boxes on the hillside. A
portion of the dripping is done in the mms way, but some of the overburden is remared by sluicing.
The plant opmding on the upper half of IXecwery in 1916 worked
the lower half of No. 1 above '' in 1917. ks them c l s h lie blow
that portion of the valley that has stsep walls (PI. VII, B ) , the
line of.duice boxes was mounted an &st1es b provide ths n w r y
grade'and dump room for tailing& A novel f+entureat this property
is that bokh stripping snd hoisting am done by a dd-line scraper,
*hi& is a modific~tionof the drag-line =raper used in otherAlaskan
m i n i districts.. The bucket bas a eapacity of a ygrd and a half.
On account of the Iaqp sim and angulsrity of t h ~M d e m and
the extmrnely uneven and blockg charader of the bedrock, some d 3 i mlties h ~ v been
e experienced with this equipment It appears likely
that the bedrock will have to be cleand by .hand, a it is on other
pmpedm. The mnditiona of. operation an Willow Creek for a
scraper ?f this type are probably ss d a d t ns will be found anywhere else, and i h m&l
operation here -would w-t
an invsstigation into the possibilities of ib economical use a t other Al&m
f
-
a
?
m
~
cumphi. The m n d d and maUm gravels on Dhppointment Creek
appear to o%ermom favonrble conditions for such a scraper than is
affordedby any of the plmr ground on Willow C m k .
During 1916 the most extensive mining operations on Willow Creek
wme on the lower half of Discover~rclaim. Operations were continued in 1916,and one shift of men was employed shoveling into the
sluice boxsa The sluice-box amnpment differs from that on other
properti@, and a greater effort is made to save the fine gald. The
upper four b x e s into which the gravel is shoveled have false bottoms,
in which are 2-inch holes, spaced 4 b 6 inches on centers &?ow
this in the line is a box contahing Hungarian riffles, with a 6-inch
drop to a mud box. The mud box, like the three sluice-box lengths
that follow it, has pole riffles of the m a 1 m e . At the other properties on the creek-all the sIuice boxes carry pole riffles, made either
of Ioesl spruce polas or, when it is obtainable, of sawed 2 by 2 inch
lumber. The lumber r i f l l ~ sare generally faced with %inch strap
iroa
M ' i was done on the upper end of the Bumblebee eldm early
in the summer of 1916, and a small area of ground was worked o u t
Operations were then shifted to the claim below, and preparations
were made for more extensive mining. A sluiceway had been exmoatad 8 or 10 feet to bedrock, and boxes were being put in on Aagust
27, whm the writer left the c m & The conternplatd operatiom
included the sluicing of both the overburden and the auriferona
gravers from No. 2 below ,' through this line of boxOn aooonnt of the small drainam basin of the creek, the water
supply for the claims lying above Discovery is likely t o be somewhat
scanty d m them are frequent rains, By the time it reaches. Discovery claim even this scanty a p p l y has been somewhat lessened.
Tho operators on Discovery have diverted tha water from the East.
Fork of Willow Creek1 and sn inereaspd the amount available for
this claim and tho= below it. A ditch from Slope Creek was confitrulcted late in the summer to hrnish an additional supply for the
mining operations on " NO. 2 below.'"
Discovery claim lies s h t opposite the front of the range of hills,
which marks s d*nct change in the topography. Below Dimvev
daim them is a wide, mleming apron which slopes gently down to
Spmm Creek and the Yukon, as illu%trsted in Plate Va, B. Above
this topographic break Willow Creek has a V-shaped vaflq with'
walle of fairly stoep slope ; below it the stream has intrenched i h l f
but Little in the frontal epmn, across which it Bows at a p & e n t
lower than where it is confined within the valley. There a p p m to
be s suggestion of a beach line between elevations of 51H) and W0 feet
(see PL on,.in ptxket), and the change in the topography occum at
h u t 500 fed or m e w h a t lower. This tapgraphic k k may
m s k the pasition of a beech, and come evidence hae been fonad near
Marshall to c o n h the wgption of the topographic form. F q m a t s of shells are rsporkd to have been found in 1817 in proapect
holes a t an elemtion of about 450 feet on claims on lower Willow
Creak. The widening and somewhat itregular aribution of tha
rruriferons p v e l s below Dimvery may be duo in part to beach concentratioil and in part to c h a w in the chamel of the dream &fore
it had k o m intrenched in its present mum.
The depth to bedrock rangw from about 6 ta 18 feet. On No. 1
above " it is from 12 to 16 feat. The upper half of the deposit consists of soil and angular rock .fragmenb with comparatively little
rounded gravel. This is dripped off before mining the lower layera
Gold is found both above and below a clay Beam Iying about 2 feet
from bedrock, and aoma of the mars&stgold occurs above this seam.
Tha bedrock L eztrameIy rough and blocky, and just above it there
are R considorable number of large angular boulders, part of which are
talus boulders fmm the valley slopas and pwt mpresent frast-heaved
h
material from t h e greenstone bedrock. On the lower claima them asp
pear to be mare rounded gravels, but the bearock is similar in character t4 that on the upper portion of the creek.
The gold in somewhat rough, and some of it appears rather porous.
Over half of it is coarser than will pa- through an & m d screen.
Nuggets valued a t $5 to $10 am not uncommon in the clean-ups, but
few worth over $20 are found. The very h e gold saved constitutes
only a very msll percentage of the clean-up It is believed that t'ha
installatian of devim for saving the fine gold would be warranted, as
Borne of the fine gold already saved ia flaky and light, and it is quite
w b l e that a gr~rrkproportion of this light gold goes through
the boxes than is saved in them. Few a w y a of the Willow Creek
g ~ l dare available. One of them is aaid .to have given a valne of
$1830 an ounoe. me gold passes current at $17 an ounce.
MAgnetite ia one of the most common minemh associated with the
p l d in the clean-ups. Ihenits m u m h m a l l amounts. Although
pyrite rnRy be Been here and them in the p n s t o n e near the head of
the creek, little or none is found in the concentrah, axidation havh g rnnosrted it tn hematite. Shot is frequently found in the heavy
resulting from the clmn-up, A few grains of platinum are
mid to occur in the mncentratea
Anvik River nnd its tributariw bsve been pmspedd ever since
1900, and p d b l y even Gfom that time. Gold has h found on
the bars at numerous locelitiea, but never in &cient mmmk -bo jus-
.
ii
.
e
7
a
t i 0 mining operatiana It is reported, howeper, that in the winter
of 1918-17 t w o men wew pr~spectingon this stream and found warkable plmm, upon which work was being don0 in the gummer of
1917, Platinum in considerable amount is said to a u r in mcjation
with the gold and i~ m i n d with it.
Practically all the other large strenms accedbla by a poling boat or
canoe have also been pmspected, but up to the present time no commercial placers have been discovered on them.
s
5
@OW) rnDEB.
,
*
.The hills in the vicinity of Marshall have hprospect4 to find,
the lodes from which the placer gold hns been d e r i d A nun~bec
.
of lode claim have been staked in the Kuyukutuk basin, on the north
aide of the ridge extending enstward from Pilchar Mountain. Little
development work is reported as having been done on th- claims,
and they were not visited. Free-milling gold is mpFted &om quartz
veins near the h e 4 of Edpr Creek, and claims have been staked
then A number of quartz veins were seen along the crest of the
divide between Wilson and Spruce creeks. Claims have been staked
t o cover m& of these veins, but no evidence was seen of work having
been awe upon any of them except on the east side of Willow Creek
.nearits head.
The group of daims on the east side of Willow Cmk, known as
the h o l d lode, was staked August 8, 1914, by Thomas Plankett.
The development work consish entirely of o p c u b made with a view
t4 determining the siee.and continuity of the veins, of which a mumber are exposed. One of the lowar veins has been traced along its
drike for over 100 feet by a seriea af trenches, 2 tn 6 fmt deep,
through the talus and dido of the hillside. T h e vein is fcDm 8
inch- to e foot in width and shows free gold in places. Farther
up on the slope a cut has been dug about 30 feet into the hill, so that
there is exposed B face 12 or Ib feet in height and 3 to 8 feet wide.
In this face apperrm a quartz vein ranging in width from 4 b 8
inch^. The minerals in the vein include calcih pyrite, galena,
molybdenite, and free gold. In plaees the pyrite hag midieed, and
the quartz t stained with iron oxides. T h e vein shows numerous
cavitie formed by the removal of pyrite and calcite. In some of
these cavitias s m J I g l a q qua& crystals may be seen, topther with
an axasionaE metta of calcite crystals. Some of the dirt from the
') bottom of the open cnt was panned. In addition ta the vein minerals
mentioned above, the concentrates from panning included s m ~ l l
amounts of wulfenite, Qe yellow to orange-colomd molybdah of
lead, and anglaqita, tha white mlphate of lad. Magnetite and the
oxides derived frm the elterntion of iroa pyrite ars dm p-t
in
mnGderable m u n k The 90of the latter minab is the
greenstone connky rock, the hanging wall in placers showing strong
pyritization, Veina near by show a m e 1 1 amount of chaloop~te,
accumpanied by the characteristic p n stain p d u d by its oxidetion. Similar minedieation has occurred in the qua& veins that
appear in the bank of the river a t Marshall.
Q
C
No veins carrying ~ n t h o n yare h o w n within the rtreas 4&ed,
but at Pairnint it was reported that stihike m u m in t h e group of
hills south of the Yukon, near tba Kuskokwim.
Data repding the mindisation in this region are not dcientIy
compIete to justify positive statements regarding the mum of the
gold, but some inferenma concerning it can be drawn. Wherever
gold has been f omd there are also soda p n i k or porphyritic daeita
dikes, many of them of considerable width, and it is believed thak
the mineralization wa9 consequent upon the intrusion of both the
s e d i m m h ~.grid igneous m k s by these p i & and dmitas. The
dacites are similar in chemical composition to the soda granites and
diffarfrom them only in having a somewhat h e r groundmass and a
porphyritic hxture. T h q repr-nt offshoots from the larger igrreous masses or wero derived from t h e same d i c pi^ magma.
Both the larger granite masses and the dacite dikes appear to have
been concerned in the mineralization. The quartz veining that foll o w d is alsa related to the intrusions, and much of the $old ocmw in
the vein qua*, but wall-rock impregnation has also Eakm placa
B&des the gold the sulphides of iron, lead, molybdenum, and copper o m r as pyrite, galena, molybdenite, and chalcopyrite, in the
veins and mineralized wall rock. These minerals have not been found
in the soda granites or d s c i h but doubtless were formed .as a o w
qvenoe of their. intsnsion.
As the m i n d h a t i o n was attendant upon the sods granita and the
porphyritic dacitea, it follows that streams which drain a m where
these. rocks appear afford the m& attractive field for prospecting.
Exposures are few in most parts of the region but may maIly be
found along the crests of the ridges or here and there along minor
streams. The
of the gravel along b m , however, will adord
quih as effectively an indication of the nature of the rocks farther
upstream. Vein quert.~OF pebblm of light-colored &tic
or porphyritic igneous rmk should be noted. T h e rwks from which thesa
pebbles are derived are of course not nec~=~riIyaccompanied by gold,
1
,-
.
MIXEEAL REBOWRCES.
65
..*
8
, .FI
but, on the other hand, in &hisregion fie g~1db a always
~
been found
hnder mnd4tions'which indicate-its derivation frotn these intrumvea
- ' OIPthe.mpprmc o r n s of most of the atreams the d e y % am cornpmhtively .narrdw mid the depth to bedrock slight. mirhing cm*
&tting af the chnnel fairly easy. On the lower reaches,.howemr3
the width is gmatm,.in some places being m ~ e r a miles,
l
and the valley
Hl is of nnlmown.depth. Prospecting under auch conditions, taken
fR comedian with &thepossibility of d a n g e s in the position of atream
eonma since the wncentration of the gold in placers, appeare uncertain to yield profitable results.
.. .-..
- -..:
?E
&
I
.*
C O ~ ,
T
The pmmca of coal on Anvik River hm long been known and is
mentioned by
It seema to have been used ta a moderate extent by the nstivm, who f ormefly employed it in the manufacture .of
a black pigment. A small amount hns also been k e d for blacksmith
ooal a t A n d , but so far as known no other utilization bas been attampted. The following information regarding these deposits was
obtained from Mr. F. H. Krupr, a merchant and prospector at
hvik.
The ma1 mama crop out about 45 miles above the mouth of Yellow
River, or omr 100 milea by water from the Yukon ;the air-line
tance to the nearest point on the Yukon is probably about 35 milea.
Anvik River cuts diagonally across the sedimentary series, made up
6f sandstones, shales, and coal hds, which appear for a distance of
about 5 milw along the course of the stream. Both up and down
stream from the sedimentary series are rock of igneous origia
Within the series ma1 seams a p p r for nearly rr mile along the river,
mast of the outcrops on the east bank. One seam has a t h i c h m of
&bout 10 feet, and several have a thickness of 2 feet.
Transportation tm the Yukon would entail a high e x p e q as only
m a U paling bolata cohld be used except at high-water stage, when
ma11 mows and power boa& might be utilized. Transportstion
overland waald prove feasible only if the Jwal market we& mfficiently g r e ~ tto warrant the construction of a r~ad,~taftm,
expIbr8- '
tion ~ n ddevelopment work had proved the extent and quaytbg of
the coal: .
b
l seama of varying thickness will doubtlaas be found dsswhem
in the areas of Cretaceous mch. 'Many framenh of Fp'~trtbed
mil wem fomd i s t h e high gravel bank on the east hfde "of'myehok
River a h t 45 miles from its modth. It ie likely that thtlee9mp
have not bmr carried for any p t distnnM and, thdleaWtt1
rlu'
, . ~ F w * ~LL
~.W
. -.OL
tee Y&O% c l u u : . u . . s . . o ~ ~ : & v . a ~ ~ . ~
p a+
lea.
,., - * - s a m . ~
'
9
.
a
from which they warn ddved.
Like thme on ths bnyik these beds when found would probably be
of lucal value d y , u n I a they were of considemble extent a d the
cod of such a quality as would permit it to compete with other fueh.
At Mamhall it was learned that m l occurs on one of the m b
which flows into a slough of the Yukon .about20 miles above Marshall. No information concerning thh deposit other than he faat
of its occurrence was obtainable.
A narrow band of bituminous shale occurs in the vicinity of the
old fnrt s t hdmfsk-i.' The Bussians attempt4 to utilise this shale
for fuel, but it was too impure to burn well, and the a-pt
was
abandoned. Thia locality is a few miles down the Yukon from
Andreafslti, where field work was terminated in 1918, and was not
visited by the writer.
M I W U mmes.
Abont 7 milm east of south of Marshall and half a mile from the
Willow Creek Imding are what arb known Imdy as the M a
Springs. Analyses show the mineral content of the waters from thwe
springs to be cbiefly caldum and bicarbonah, with considerable iron.
Free, carbon dioxide is constantly being fiberatsd and b u b b l ~up intermittently in almost all the pools and springs of t h p u p . Some
have built up considerable cones, 4 to 8 feet high and 10 to 20 feet
wid&at the b m (Sge PL VII,A.} Ths ~nahrialin these con= as&ts of lime carbonate and yellow and red iron oxides. At the northem edge of the p u p is an extensive
covered with granular praoipitotsd oxides +ofiron, with some lime carbonate, which is rather
loow: md incoherent, much resembling gss-house cinderpk It has
buil t'up r deposit thick mough to afford a solid footing, much ia contra& with t h a t d the soft, spongy moss-covered areas near by. That
very little vegetation g r m s m the sinter is indicated by the photograph of the cune, (See Pl. VII, A, p. 60.)
Between the main group oE springs and the lmding are a number
of pools of water which in part may represent the o v d o w frrnn the
sp*
above and in part may be the.bmsins of other spring^ hming
B COmparBLtivelymall flow. The depmits in the PiciniQ of these
chiefly of lime carbonate and are wnspicuous for their
whib mk>rand manty growth of vegehtion.
%
are situated rtE the base of the muth froataI slope of
&e -ge of h a between Spruce and W h n creeks, A mantle of
-tion
and,nncc,~lsolidatedmaterial so complet?I y covers the
tha$ it ii3 i m m b l e to determine the natnrs of the underI&
badrock. It appeam likely, however, that the aprin,@ oociur
~ m ~ d would
b g reveal the, seams
I
3 4
&
./
-
a ~ d W.
, H.,
.
arrd Earrls, Q.
p, 847, 7,1882
.
X).,
Correlatloa wperr. N m e :U. B:&oL
ImfeB BolL
?
.
3
-
M
rS-
?
I
67
~ RESOURCES.
L
near the contact of the Quaternary lavae- and the greenstones which
make up the ridge to the north. Other springs of assentidly s i d r
cha&
are reparted as occurring about 12 miles t o the east, where
the topographic situation and geologic conditions #re much the
m e as at. this locality.
Little utilization has been made. of these minerd wal;em The
spring &own in Plate VXI, A, wm dug dawn about 3 feet or mom
from the crest of the cone, and a m a l l bestin was dug below the rim
of the outlet. This spring flows a few quarts to the-minnte. T h e
wahr is carried up to the camp on WiLlow Creak and used ta ta mall
extant ae a tabIe water. A few hundred yards to the north another
spring bas been dug out, the cone leveled off, and s log building
e d ' o v e r it. This building was in nse as a salmn, and the basin of
the spring sefvsd botb for cold dorage m d as a source of carbonated
water.
Iln mdysis of this water bp R
gave the following results :
AwMrb of
B.Dole and Alfred A. Chambm
W U ~ Wlronr Bsde ISprfnpd,
near HarshalF
Parta per million
mca (51015 --,,,,,,-,-,,-------40-------~roa(Fe]
----- ---d2*
blnmlnhm ( M )
,---------,,-,,,---,---------4.0
--1
1
--------,
-,
---
Caiclctnm
886
[Ca)---,,-,,,,,,,,,-,-w-------L--+-+~~--
Magmslnm (Mg),-----------,,,---------------------,58
W i n m [Na)-----------------------,--,,,----,,,,,-32
Potastttm 1K)-~------------------ttm--ttmttm~ttmttmtt
14
Carbonate radicle (GO3) ,-,------,------,,,,
,
,
,
,
_
,--.O,,,
Blmbonate raaicle (HCO,) -,,
,
,
----------- ,,,,,
,
,
,
,
,
,
,
1,$58
Snlphate radicle (SO,)--,--,,-,,-,--,,,---------,
18
Chlorlde radicle (C1) -------,--------,,------3.l
Kitrate radicle (NO*)
-----------------,---------------!T?sce.
Total dissolved solick at 180" C
------------,,------I,270 .
Free Cd----------------------l------------l1,340
-,-+
-
1,
Watar for analysis was taken from the open spring and ru, had
last some free GO,. It is possible that =me of the iron may have
been precipitated. In precipitating from solution the iron appears
to have gone out M,
so that even the d l percentage shown by
this analysis would account for the presence of the iron minerals
near the vents of the springs. Iron oxides make up a considerable
amount of the sinter but appear to constitute s, much larger part of
it than they redly do, a6 both the yellow and brown sinter contain
coasidereble lime .carbonate, the presence of which is conmalad by
,\-&a color of the i ~ minerals.
n
=Wsrins: a. k,mnsr*l -am
4l8, p 87, Lnll*
He. 4 i a l t
d Alamkm: O.
_<.
S a r ~ e gwater-Su~pbp
aw
-1.
"_
-
_
,,
_"...
...-+- -
I
. m.
tm a,,-,--64 Detormatlon In Cremcem8 IradlIf
men- ------------8-8
mvhum. h t m m 0L,
,
,
,
,
,
,
LeLnarrl-
3
Devlt's Hllbo*, Greta- pedlmmtr
ntar,,,
--,,---W
)
Morltes, nature and BiBtrlIlatlw of- 4 4 4 6
Meappohtment Creek, gold on,,,,
67,lis
Dog8sh Village, Chtacwna wdlrnentm near ,
,
,
W
Dole, R. B.. analssii by ,
,
,
,
67
Drainage of the r e g t o n - - - 12
Driftwood, deposition o
t 4S+4
21
Altlplmattm, rwnltB of,
,
l--,
kltiplmatlon terra-, famtlon ot,
66
+
p u s ah-' , , , , , , , ,
,
,
,
,
,
,
,
22
b d e d m a , mtom md dl8trlbution
I
of,--,
404'1
w,
bl-bW
#ha0 ntsr-,,
88
Andrrataki klrar. gold on ,
,
,
,
,
,
,
,
,
M1
-
+
Cntnccour oedlrnentn aenr-,,,
m e s i t e , oecarrence
-&.
Idnds and prevalwfe of-,
81-32
83
18-19
Shkln, H. Y.,aclntl.rledgmmt to6&
dnttmouy, occurrence of-,-,-,,-,,,
64
explomtiuu b~ ,
,
,
$
hnvih Elver. coal an ,
,
,
,
,
,
,
,
,
,
,
,
Rb
IWmr Creek, mld m
63
Cretecewa a e d h e a b on,,,,,,,
28
Elcphant Creek. mld on ,,---- 60
pdd ba ,
,
,
,
,
L
,,
,
SB,1%3S
,
,
,
t
m67
8
A t m d , W. W.,~ p l o r r t h nbg,,--~mbarrn~nta
in ahom# of the 'lT54-56
B
Ballq. C. F., wbrk ot---------Eroslon, embaymeat mtde br, in
B n d f &th o!, cuttlag borlsbnM paY a h RIvet bank,
mlt down, phte abowplate & o w l u g , , ,
22
. @p -----,,-,-,
29
-,,,-,
meld
m
r
k
.
m
r
d
oi
,
,
,
,
,
,
'
6
Basal@ ape and ctirrelatlon
,,to
4MO
Flub, Hnda and pwmlence
,,,-fo
11
di6ttlbtiffon of ,,,,----,47-48
,
,
Flora, coflectlon of ,
,
,
,
,
, ---1GIR
-,,
Itthology ot,-,,,l---,,,,
48
19 Food.pdccaof--- ---,
,
,
,
,---,,
68,
*,
Hnda &nd prevalence of---,,
For-,
klnda and dl~trlbuthnM
,, 1&16
Bonrailn Worne, dencrIptlon of,,,,
10
Fosalln, occatrenn of,,,,,,,
83-84, 40-41
B m h , A. H., d o b e on Marshall dl&
trsd by ,
,
,
,
,
,
8
W,occurrence ot-,, ----,,,,
63
,
-ewaod'mdiQwlagiC blstoq of the rtglon,,,,,,
6660
menta, sge and mrrelrQeologp o t the ne&loa,
,
,
,
,
,
,
,
,
22-50
,
tlon 0L
,
,
,
,
Ztl
Gllmore, C W., I o d l n collected by,,
40
& &Ietribntloaof
23 Glazanof, erploration by,----,,,,,,
fl
Ilthology of--S 2 5
Gold, lode deposits of ,
,
,
,
,
,
,
,
,
,
,
,
&W
structure of
25-26
plawr depoelts of,----,,,,
6-lc
time, evmb-oZ
6r
source of-+--,--,,-,
,
,
,
,
,
,
,
, 81
Chalcomte, ~rtencs~of---,
&1
boodr~ch,R. B.. exploration bg,
,
,
, 7-8
87 Graveis, older Quaternary, nstnre
-behliffd A., nwl~ulmbyChRplTm. Eer. J. W., SehOWletIgand diatrfbutfon of,,, S T 4 1
.
m a l t ta
fl
tmader of ---,
,
,
,
,
,
,
,
, 84
Chan, Yrr. &mu, p h t n dete*.
Oreenatonm Carbonliema, -tam
medbf,------,,16
,
and dfstrlbutl6n of-,- 2 M 8
40
dm&, W. C., l&la colleacS by--,
CbWIkWk, d d p t t o n of, ,
,
,
,
,
,
1041 Eematlb, -oe
of------,,19 tlf
p r i l n n k BTwr baala. CMacwan
, Klnckley, F. C., exploration d,,,
8
wUfrneota In
81-42
BOllick, rCrth~r,f ~ L ~bl l & d by,
.8
h t e of tbe re~lon,,,,,,,
12-24
fmdb detembed b y - - - - M
b4 met of ,
,
,
,
,
,
,
,
,
,
,
,85-88
Holy Crone, weatber records at18
and Orodetie Stlrrey, mapping
Homan. Cbarlen. mapplng br,
,
'f
by,
,
,
,
,
,
,
,
,
,
,
,
,
,
1CP
&lll=,
'A
explohtion b y - 8
I a e a a e rocka, nature aad distrlbtr
&dhdmtIon, meaaa of ,
,
,
,
,
,
,
,
,
, II
tlom otL----,*
,
,
,
, 4440
mlirnenta. sm md corbemite, occurrence o f - ,
82
rclhtlon of------,,,,,
8 M 1
med -bution
af,. ,
,
,
,
,
,
A
,,
2&27
Kako R I w ,-,gold
,-,:-no
W
Iltaolow and atmtkmphy of-, 27-28
Enowlton. F. H3 faWln
,,,,,,,,fo
PW2
. _ I o d,,rahram
- 88
i~ .trrreturs of,,,,+.,--,,,,
82-83
Komerefskl Elver, Greta-I wdlmeatx. near-,
%
natars an# M W t h of,, 4 8 4 7
tl =roger, F*3E, admewleagment
P111. W. &, ~ ~ p l o r 8 U abay,&5
.
I
a
,
el
TP
-----
--.-"
-0
rmQ
ra+aq.
UQ
mea
xog*El
--
yo nonnqw.1~
-------
. 7 0 manJLm3Jo %Pu
w-m 'ee
9e-W
ZOJ m0-m
' S ~ I i 0
~ 2 - o--:--aom*r
~
aqa ab u o n q n d o a
zo waar~n3so' m U U R P r d
:--fa W ~ ~ P J'TmnaOX
B ~ Q AaWTId
------
EO %tP 'BQ
1
P)-8)
EZ
09
8
'M
"-"
8P
BE
~
"--" JV a a n a ~ m ~pup
o salvo
duwoss a l q d *ao?n&
ow $0 imsq awn q 'q
-----."--'-IqUaAa %$0
-4---6q
-"
----
ja
3-d
3T0#&18.3
noRwo[dxa 'aaaptg
--------
m a o pm
0'E-B
@z
"
"
I
4m ao a ~ o ~
6qe paam
-dms 90 &
PI-'lsmqm16-'
w-m ------
P =ma
'mpodap
emrm
mmnm
'
ammo
S t q W o a l 'wmrH
m-
30
'rn*v..PllgP
no PI^
'
I
"
"
"
'
'
"
'
srptr
qrmm
I
"
"
-
-mas m o w g w ~'qaaz3 m m o ~
amqm 'UJapom wpomp mwwg
08
--*-+-88
-*----*-- l o w m - o
*mraa~qS;a~
.
Q
fP-99
"-"""-'-'-----P AJOl'Wl
m a t a p m o a "IYL '& 'rro?ams
gptq --~qlsap
avonose 'nncmm
mt
6q paafm
+Q
ao mmerafal " a o ~ i w ~ ~ ~ e u ~ ~
- m a p qaPId '-3rnsd ' J a m s
so aana~anaaoLatan&~ ~ ~ a u l ~ f
bq u ~ m ~ o l h'*g
a *p '~md@Lg-BB
&
YO"
jU@UfUO[aA9p
no p ~ f
da a q mnadg m - 9 P '"'pun s3nasJnam 'uasanwaa 18mnm
~ ~ - ---p
8 9
wnaunam yuJarrlrn 'saq~as
$0 sraeaa *amla alo!maafi
tz
~
~ w q d %adow
~
~ ~ ~o3 n u n oT~(sS W "-"'----s
03
!Zl
JO upaaa 'rro~mgno6:
3 n ~ I M o u w'xt ''8 S 'enam
L9-90 '-"-p uo~dllsnap'u8apdg wpog
gT
Q p
a
w
09
Sqfioqs
m q d 'w m m M hmm
m d 'yo
r m n l a m d u m gS'89 -wep
'---"",.----"'-'J-a P W
JO u o u
m ---"-"-'-"
I W U rlE3qp-m moasrJP33
-Wwslp Pas %JrU*o -wmrQ
rpos 99
asam im ' w q m
&
"---'
Lq uo~au~oldraa * @ *a
TWO^ E I
rn
30 iaama8n' m o q WIOM
mFqqP l=t=v
mm-x
P
Bq~oqe
3 v
UPOM Jo -0s
3qqS
TWJWPW-WArrV
Fm h ~
------
-----------
a
-----
I
"
----------
-
---------.-------..-----*-----
-----------
--------
=-
I
"
"
w p ~
----
08
Bir
---
am
"------
d UI
'UO@l
Plgd
---------=m
---- ZQ
-
~t-18
mm m
EM0
L
8-1
II
7 0 m o ~ r m z o J' x q w
a= 'aCslnnOlA tarns
uwnqlaarp
'b~-uwrmb camo h n g
$0
------------------
)9-89 'zg
j a w a a l a m *aJnea%sR
&g uolamo[dfe
-01 yuamSpafrornl~uO.9 T ' a a ~ p m
am 'aer~l-qqm' e w g
'
I
----------*
kq
UOfT
www-& anam 4-rn
4n ~ w ~ o '-3
~ d;Ba' ~ a p r r q ~ g
I
70m
-
a
C~
-
'XI ' 3 - r o ~