geology of cumberland gap national historical park

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Structural Geology
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Major structural features in this area include the Pine Mountain Thrust Sheet, Middlesboro
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Syncline, and Middlesboro impact structure (see Geologic Map). Pine Mountain is the
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northwestern, leading edge of the Pine Mountain Thrust Sheet, a fault formed by lateral
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compressive forces in the sedimentary rocks. A fault is a fracture or crack in rocks along
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which there is some type of movement. The thrust sheet contains rock layers that were
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pushed up from deeper areas in the earth’s crust by ancient forces (320 to 200 million years
Hillshade and Physiographic Map
ago) that were building the Appalachian Mountains to the southeast. The Pine Mountain
The landscape in and around the park boundary. Significant topographic features are Pine Mountain, Rocky Face, Dark Ridge, Middlesboro Basin, Cumberland Mountain, and Powell Valley. These major features mainly stem from regional tectonic and geologic
Rock formation along the trail to The Pinnacle overlook. This is the
Thrust Fault is exposed at the surface at Pine Mountain, the rocks dipping toward the
events. See Structural Geology.
sandstone
and
conglomerate
unit
(tan
color
on
Geologic
Map),
a
resistant,
southeast; but below the surface the rocks are horizontal and extend toward Cumberland
cliff-forming sedimentary rock. Photo by Brandon Nuttall, Kentucky
Mountain, where the dip is toward the northwest. The entire thrust sheet containing the
Geological Survey.
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dipping sedimentary rocks forms a U-shaped fold structure called the Middlesboro Syncline.
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Cumberland Mountain is a resistant limb of the syncline and part of the thrust sheet (see
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miles long, broken by one conspicuous pass: Cumberland Gap.
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The gap in Cumberland Mountain is a result of a combination
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of natural geologic processes. Cumberland Mountain is in the
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sandstone and
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middle of the larger Pine Mountain Thrust Sheet. Thrusting
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deformed the once flat-lying sedimentary rocks so they now tilted
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roughly 40 ° toward the northwest (Dean, 1989). The rocks
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northwest of Cumberland Mountain were further deformed by a
mixed clastics with coal
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different north–south-trending fault called the Rocky Face Fault
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shale, siltstone,
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sandstone and comgolmerate
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thrusting that created the Pine Mountain Thrust Sheet (Rice and
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erosion of the rocks, forming the gap.
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Cross section of bedrock geology through part of Cumberland Mountain showing the main
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structural
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The Middlesboro impact structure is a meteorite impact site
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No vertical exaggeration. Some layers have been combined for simplicity. Modified from
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in the Middlesboro Syncline. It is defined by its circular alluviated
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basin, circular distribution of faults, and highly deformed rocks
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(see Middlesboro Impact Structure).
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Fog rolling through Cumberland Gap. View is looking west from The Pinnacle.
Photo courtesy of Wikimedia Commons, commons.wikimedia.org.
The natural break in Cumberland Mountain that served as a passage toward the west for pioneers in the
late 1700’s was also a strategic feature in the American Civil War (1861–1865). The Wilderness Road that
Daniel Boone made so famous served as a natural invasion route for Confederate and Union troops.
Cumberland Gap was the place where army forces were led to the Bluegrass Region of Kentucky or to the
southern supply areas of Tennessee. By the end of the war, occupation of the gap had changed hands four
times, yet no major battles were fought there (National Park Service, 1999a). Earthwork fortifications and
gun emplacements built by both armies are still visible in the park (Andrews, 2003b).
Wilderness Road, going through Cumberland Gap. Photo courtesy of
the National Park Service.
Overturned (nearly vertical) layers of shale, coal, and siltstone in the
Middlesboro Basin. These layers are thought to be material that was
ejected along the crater rim during meteorite impact. Photo by Brandon
Nuttall, Kentucky Geological Survey.
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Although not in the park, the Middlesboro impact structure is a significant geologic feature in the
southern Appalachian Mountains. The town of Middlesboro, Ky., is situated in conspicuous topographic
terrain, in a broad alluvial basin with steep-sided bedrock valley walls. Many of the rocks in the basin
are highly deformed, folded, and faulted. Numerous theories have been examined through the years
as to the geologic history of the Middlesboro area.
It wasn’t until detailed geologic mapping in the early 1960’s that geologists interpreted these features
as the site of an ancient impact. The presence of a circular basin, deformed rocks, circular patterns of
normal faulting, overturned sedimentary beds, and a central uplift area are consistent with impact models
(Milam and Kuehn, 2002, 2003). Impact craters are typically circular depressions that result from a
meteoroid colliding with a planet (Milam and Kuehn, 2002). Instantaneous, high-energy impacts release
huge pressure and temperature on the surrounding rocks. In 1966, detailed rock and mineral analysis
revealed shattercones and shocked quartz in rocks near the central uplift area (Bunch, 1968), providing
more evidence of an impact origin. Shattercones are cone-shaped features that contain thin linear ridges
formed by shockwaves from a meteorite impact. Shocked quartz is extremely deformed quartz grains
in rocks, caused by intense pressures that can only be created by meteorite impacts or nuclear bombs.
No meteorite fragments have been found.
A meteorite approximately the size of a football field
is thought to have struck what is now southeastern
Kentucky sometime less than 300 million years ago.
The circular depression (crater) in which the town of
Middlesboro sits is approximately 7 kilometers in
diameter. Although weathering and erosion have reshaped
the landscape, a good view of the impact structure can
be seen from The Pinnacle in Cumberland Gap National
Historical Park.
Middlesboro has been designated by the Kentucky
Society of Professional Geologists as a Distinguished
Geologic Site. The Bell County [Ky.] Historical Society
commissioned a state historical marker signifying the State historical marker designating Middlesboro as a
geologic history of the Middlesboro meteorite impact Distinguished Geologic Site. Photo by William Andrews Jr.,
Kentucky Geological Survey.
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Cumberland Gap is a natural pass in Cumberland Mountain (part of the Appalachian mountain chain) that
creates a gateway toward the west. Migrating animals such as bison and elk first took advantage of this gap
and forged a trail that connected several Native American territories (Algeo, 2003). By the mid-18th century
European-Americans wanted to settle in the fertile, flat lands of the Bluegrass and Nashville Basin that were
west of the Appalachians. Private land companies aided in this venture and received grants for vast tracts
of land from colonial representatives who wanted explorers to settle the West (Algeo, 2003). Thomas Walker
of Virginia is often credited with being the first European-American explorer through the gap in 1751.
American pioneer Daniel Boone crossed the gap in 1775 and made it part of the much larger Wilderness
Road system that allowed settlers to reach Kentucky. The latter part of the century saw more and more
settlers start to migrate along the Wilderness Road and through the gap, making it a key passage into the
western frontiers and an important part of American history.
Middlesboro Impact Structure
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White Rocks. These rocks get their name from the very light gray and tan color
of the resistant sandstone and conglomerate that is exposed as a massive cliff
on top of Cumberland Mountain. See Geologic Map for location. Photo courtesy
of the National Park Service.
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The Cumberland Gap area has a deep connection to many periods of American history. Geology plays a
major role in many of these significant events in human culture, both past and present. Geologic and cultural
features discussed below are labeled on the maps.
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Geology and Cultural History
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Panoramic view from The Pinnacle overlook, looking toward Powell Mountain, Cumberland Mountain, and Middlesboro Basin. Cumberland Gap is not visible in the photo, but is below the railing in the right side of the photo.
Photo courtesy of Wikimedia Commons, commons.wikimedia.org.
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The same rock type (sandstone, shale, etc.)
may also occur as different varieties. For
example, the Geologic Map contains a shale
unit and a black shale unit. Black shale contains much more organic matter than a regular
shale unit, making it very dark colored. Sandstones occur as coarse-grained varieties, with
larger sand particles, and also as fine-grained
varieties, with smaller particles.
The layers of sedimentary rocks have a
mountain-building and erosional history that
led to the unique landscape in Cumberland
Gap National Historical Park. The narrow
ridges, steep cliffs, overlooks, steep valleys,
and natural gaps owe their existence to uplift
of these rocks (see Structural Geology), in
conjunction with millions of years of weathering and erosion that break down the rocks
and shape the landscape. Significant geologic
features in the park include White Rocks, The
Pinnacle, and Devil’s Garden. See photos and
locations of these features on the maps.
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The rocks in and surrounding Cumberland
Gap National Historical Park are sedimentary,
ranging in age from Cambrian to Pennsylvanian (540 to 295 million years ago). Sedimentary rocks are formed by the compaction of
particles of gravel, sand, silt, mud, carbonate
minerals, and ancient seashells. The vast
expanse of time represented in the rocks
conveys a complex geologic history. The
repetitive rise and fall of ancient shallow seas
allowed for the various types of sediment to
accumulate, including extensive swampy areas
that eventually formed the coal beds of today.
The sedimentary rocks present in units shown
on the Geologic Map include sandstone,
conglomerate, shale, siltstone, limestone, coal,
and dolomite. Except for limestone, these
sedimentary rocks are described as clastic
rocks, meaning they are made up of discrete
particles of rocks and minerals. The units are
represented on the map as single rock types
or some combination of the different rocks.
of Cumberland Gap National Historical Cumberland Gap
Park. It was produced using digital geologic National Historical
Park
mapping and geographic information
Virginia
system technology, which also help the Kentucky
National Park Service with resource
management and meeting federal mandates,
Area of
Tennessee
map
while also providing informative perspectives that are valuable to all citizens
who enjoy national parks. For more information, please visit the
Cumberland Gap National Historical Park Web site at www.nps.gov/cuga.
To obtain digital geologic and other GIS data, visit the National Park
Service Data Portal at nrinfo.nps.gov/Reference.mvc/Search.
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Cumberland Gap National Historical Park
Cumberland Gap National Historical Park is located in parts of
Kentucky, Virginia, and Tennessee. The park was authorized by President
Franklin Roosevelt on June 11, 1940, and is now the largest historical
park in the National Park System. It contains 24,000 acres along
Cumberland Mountain near Ewing, Va., proceeding southwest toward
Fern Lake in Tennessee, a distance of approximately 20 miles. The
average width of the park is only 1.6 miles.
The park hosts a distinctive range of geologic processes and features.
Unique structural geology, caves and karst, surface- and groundwater
erosion, and mass wasting are just a few of the processes that shape the
scenic landscape of the park. This publication illustrates the relationship
between the geology of Cumberland Gap and the historical and cultural
issues that are important to the park and its visitors. It is intended for
park visitors, educators, park staff, and anyone interested in the geology
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Kentucky Geological Survey
Introduction
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GEOLOGY OF CUMBERLAND GAP NATIONAL
HISTORICAL PARK
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Map and Chart 199
KENTUCKY GEOLOGICAL SURVEY
James C. Cobb, State Geologist and Director
UNIVERSITY OF KENTUCKY, LEXINGTON
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Hensley Settlement is located on top of
Brush Mountain just north of the Ridge Trail
that runs through the park. This early 20th
century settlement was founded in 1903 by
Sherman Hensley and his family and was an
isolated, self-sufficient community that used
the mountain’s natural resources for
establishing schoolhouses, a blacksmith’s shop,
a church, and liquor distillery. The settlement
attracted and supported approximately 100
people. Hensley Settlement was occupied until
1951. Many of the buildings have been
preserved by the National Park Service and
provide a good example of the rustic pioneer
lifestyle.
Geologic Map
Distribution of rock types and major geologic structures in and beyond the park boundary. The same geographic area is shown on the Hillshade and Physiographic Map; note the similarities between the rock types and landscape.
References Cited
Geologic explanation
Legend
KAYJAY
MIDDLESBORO
NORTH
VARILLA
U.S. highway
EWING
State highway
State boundary
Cumberland Gap
National Historical
Park
County boundary
Virginia
Kayjay
FORK RIDGE
MIDDLESBORO
SOUTH
WHEELER
Shale
Sandstone, mostly fine-grained
Dolomite
Black shale
Limestone and dolomite
Legend; Physiographic Map
Elevation above
sea level
Limestone
1,000 meters
Landslide deposits
Normal fault (U, upthrown side;
D, downthrown side)
Reverse fault
Overthrust fault; sawteeth on upper plate
D
U
Mixed clastics, partially disturbed
Sandstone and congomerate
Park boundary
Shale, siltstone, and sandstone
Trail
Sandstone and shale, minor
limestone
Shale and limestone
Sandstone, siltsone, and shale,
intensely deformed
Populated place
Tennessee
Alluvium; silt, sand, clay, and gravel
in streams
Colluvium; angular boulders, gravel,
sand, silt, and clay on slopes
Terrace deposits; gravel, sand, silt,
and boulders
Mixed clastics with coal
City boundary
Railroad
300 meters
Left-lateral strike slip fault
Contact
COLEMAN GAP
Location of the eight quadrangles that contain the park or were used in the compilation
of this map. Index shows names of the 7.5-minute, 1:24,000-scale U.S. Geological
Survey geologic quadrangle maps (cited in References Cited).
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Rippling pool of water in Gap Cave, formerly Cudjo’s Cave.
Note the extensive speleothem deposits (see Caves and
Karst). Photo by Matt Crawford.
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This half-dome shelter, the result of seeping water and the freeze-thaw
process eroding sandstone and conglomerate, formed differently than
limestone caves (see Geologic Map). Weaker areas in the rock erode
away and the more resistant parts remain, forming the shelter. Sand
Cave is the largest rock shelter in Kentucky. Photo courtesy of the
National Park Service.
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The relationship between geology and cultural history
at Cumberland Gap National Historical Park is also
demonstrated by the rich history of iron production. An
abandoned iron furnace in the town of Cumberland Gap,
Tenn., is what is left of a much larger ironworks complex
called the Newlee Iron Works (Andrews, 2003b). The
furnace is constructed out of sandstone that was quarried
high on the nearby ridge; since the slopes are so steep,
massive sandstone blocks could slide down the hill to the
site. The original iron furnace was built in 1819 and stood
30 feet high, but all that remains is the stone chimney. The
furnace itself used charcoal and local limestone as flux in
the iron-smelting process (Andrews, 2003b). The iron ore
for the furnace was mined from a shale bedrock formation
(formally named the Rockwood Formation) that contains
an iron-oxide mineral called hematite. The Rockwood
Formation is the dark yellow shale unit on the Geologic
Map.
Hensley Settlement
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Kentucky
Salamander on limestone inside Gap Cave. Photo by Matt Crawford.
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View of the Tennessee side of the Cumberland Gap Tunnel. Note the
dual tunnels with two lanes each. Photo courtesy of the National Park
Service.
Iron Ore
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View northwest from The Pinnacle overlook toward the Middlesboro Basin, an
ancient impact crater. The crater has taken on a different shape after millions
of years of weathering and erosion, but the slightly bowl-shaped crater is still
there. Note the coal-mining activity in the crater wall in the distance. Photo by
Matthew Crawford.
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brought the rock up, forming part of Cumberland Mountain (see Structural
Geology), then the cave development processes began. As the overlying
rocks were removed by erosion, limestone was exposed along a narrow strip
along the length of the mountain. The extent of cave development is limited
by the area of exposed limestone and by the orientation of the rocks, which
restricts groundwater flow (Currens, 2001). Cumberland Gap has extensive
cave networks, many of which are understudied. There are 24 named caves
in the park. One of the most significant caves in the park is Gap Cave.
Formerly called Cudjo’s Cave, Gap Cave is the only one in the park open
for interpretive tours. Gap Cave houses spectacular speleothems (stalagmites
and stalactites), sparkling pools of water, and endangered fauna. Speleothems
are deposits of minerals that have been carried in solution by water flowing
through the cave. Endangered species living in the cave include bats,
salamanders, and beetles. Gap Cave also provides an internal view of the
structural orientation of the rock layers, exposing the dipping rock layers
that are part of Cumberland Mountain. To learn more about Gap Cave and
other caves in the park, contact the park visitor center.
35
Construction of the Cumberland Gap Tunnel began in 1980, eventually becoming two side-by-side,
dual-lane tunnels that cut through Cumberland Mountain about a mile southwest of the gap (see tunnel
location on the Geologic Map). In 1986, a small pilot tunnel approximately 10 feet high and 3 feet wide
was drilled through the mountain along what would become the southbound lane. The project’s purpose
was to reveal the geologic conditions expected during the excavation. The pilot tunnel transects the inclined
sandstone, shale, siltstone, and limestone bedrock formations (see Cross Section). Many geotechnical
issues were encountered during the pilot project. The different rock types proved to be a challenge during
construction; thick sandstones and limestones are generally conducive to tunneling, but shales and siltstones
are weaker rocks and require more roof support (Leary, 1989). In addition, karst was also a factor in tunnel
construction (see Caves and Karst). Rock voids or caves in the limestone fill with clay and an abundance
of water, making the roadbed susceptible to subsidence or cracking. The steeply dipping rock layers in
the mountain could produce 450 gallons of water every minute (National Park Service, 1999b).
The major tunnel excavation took place simultaneously, north on the Kentucky side and south on the
Tennessee side of the mountain, meeting in the middle on July 9, 1992. The 4,600-foot-long tunnel was
completed in October 1996. The tunnel replaced a 2.3-mile stretch of U.S. 25 that connected Cumberland
Gap, Tenn., and Middlesboro, Ky. Besides
alleviating traffic from a small and often
dangerous segment of U.S. 25 that ran through
the gap, the other goal was restoring Cumberland
Gap to the way it was during pioneer settlement
in the 1700’s. The old U.S. 25 through the gap
was removed and replaced with trails on which
visitors can hike.
The Cumberland Gap Tunnel was a shared
project between the National Park Service and
the Federal Highway Administration. The dualtubed tunnel is an engineering feat and is one
of only two mountain tunnels in the United
States that cross a state line. The tunnel is a
great example of the relationship between
modern culture and geology exhibited at
Cumberland Gap National Historical Park.
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Karst processes and cave development are active in the landscape at
Cumberland Gap National Historical park. A karst landscape is one that is
underlain by carbonate rocks (mainly limestone) and contains features such
as sinkholes, caves, springs, and disappearing streams. These features develop
in an ongoing groundwater erosion process, taking millions of years. As
water from precipitation and surface streams moves underground, the
limestone bedrock is slowly dissolved away by naturally occurring weak
acids. The naturally acidic groundwater erodes the rock, creating void space
(i.e., caves).
Cave development in the park is controlled by the northwest tilt of the
rocks along Cumberland Mountain. Formed in the limestone, the caves are
much younger than the rocks themselves. Generally, loose sediment was
deposited in a shallow marine environment that lithified into limestone;
evidence of this origin is
provided by the marine
fossils in the rock walls of
the cave. Millions of years
later, powerful forces
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View west from The Pinnacle overlook along Cumberland Mountain. The
Middlesboro Basin is off to the right and Fern Lake is in the distance. Photo by
Brandon Nuttall, Kentucky Geological Survey.
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View north of Cumberland Gap and The Pinnacle overlook. Steep
slope underlain by variable rock types is susceptible to landslides.
Photo courtesy of the National Park Service.
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vegetation, and poor drainage systems can facilitate slope failure. The park
contains a variety of slope failures: recent landslides, old landslide deposits,
and rockfalls. Recent slope failures can be found along the trail to Gap Cave,
near the entrance to Wilderness Road Campground, and near the Tennessee
side of the Cumberland Gap Tunnel. There are many places in the park to
see engineered support (walls, pillars, regrading slopes) that remedy current
slides or prevent new ones in slide-prone areas. Older landslide deposits
shown on the Geologic Map (in red) were mapped on older maps.
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The natural bedrock geology and steep landscape in Cumberland Gap
National Historical Park are susceptible to many types of slope failure. A
landslide is the downslope movement of rock, soil, or both under the effects
of gravity. A rockfall is the toppling of loose rock that becomes detached
from a cliff or steep slope and falls through the air. Rate and style of slope
movement can vary.
Geologic conditions such as dipping layers of rock, undercut sandstone
layers, weak shale units, and natural groundwater flow can cause unstable
slopes. In addition to landslides from natural causes, human-induced landslides
are prevalent. Construction of roads, building structures on a slope, removing
rmile
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Landslides and Rockfalls
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190
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40
The Tunnel
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SCALE 1:100 000
universal transverse Mercator projection, zone 17: 1927 North American datum
13
8
14
15
9
16 KILOMETERS
10 MILES
Hensley Settlement. Many of the buildings were constructed from chestnut
logs and had shake roofs. Split-rail fences were common too. Photo
courtesy of the National Park Service.
Algeo, K., 2003, Historic overview: Settlement history of the Cumberland Gap
region, in Kuehn, K.W., Milam, K.A., and Smath, M.L., eds., Geologic impacts
on the history and development of Middlesboro, Kentucky (guidebook for
Kentucky Society of Professional Geologists 2003 annual field conference):
Kentucky Society of Professional Geologists, p. 3–8.
Andrews, W.M., Jr., 2003a, Civil War history of the Cumberland Gap, in Kuehn,
K.W., Milan, K.A., and Smath, M.L., eds., Geologic impacts on the history
and development of Middlesboro, Kentucky (guidebook for Kentucky Society
of Professional Geologists 2003 annual field conference): Kentucky Society
of Professional Geologists, p. 9.
Andrews, W.M., Jr., 2003b, Iron history of the Middlesboro region, in Kuehn, K.W.,
Milan, K.A., and Smath, M.L., eds., Geologic impacts on the history and
development of Middlesboro, Kentucky (guidebook for Kentucky Society of
Professional Geologists 2003 annual field conference): Kentucky Society of
Professional Geologists, p. 16.
Bunch, T.E., 1968, Some characteristics of selected minerals from craters, in French,
B.M., and Short, N.M., eds., Shock metamorphism of natural materials:
Baltimore, Mono Book Corp., p. 413–432.
Conley, T.J., 2003, Spatial database of the Kayjay quadrangle and part of the Fork
Ridge quadrangle, Bell and Knox Counties, Kentucky: Kentucky Geological
Survey, ser. 12, Digitally Vectorized Geologic Quadrangle Data DVGQ-1505.
Adapted from Rice, C.L., and Maughan, E.K., 1978, Geologic map of the
Kayjay quadrangle and part of the Fork Ridge quadrangle, Bell and Knox
Counties, Kentucky: U.S. Geological Survey Geologic Quadrangle Map GQ1505, scale 1:24,000.
Currens, J.C., 2001, Generalized block diagram of the Pine Mountain karst: Kentucky
Geological Survey, ser. 12, Map and Chart 18, 1 sheet.
Dean, C.S., 1989, Geology of the Cumberland Gap area as interpreted from the
pilot bore of the Federal Highway Administration Highway Tunnel Project,
in Dean, C.S., and Moshier, S.O., eds., Cumberland Mountain: The inside
story (guidebook and roadlog for Geological Society of Kentucky 1989 annual
field conference): Kentucky Geological Survey, ser. 11, p. 4–9.
Englund, K.J., Smith, H.L., Harris, L.D., and Stephens, J.G., 1961, Geology of the
Ewing quadrangle, Kentucky-Virginia: U.S. Geological Survey Geologic
Quadrangle Map GQ-172, scale 1:24,000.
Johnson, T.L., 2003, Spatial database of the Varilla quadrangle, Kentucky-Virginia:
Kentucky Geological Survey, ser. 12, Digitally Vectorized Geologic Quadrangle
Data DVGQ-190. Adapted from Englund, K.J., Landis, E.R., and Smith, H.L.,
1963, Geologic map of the Varilla quadrangle, Kentucky-Virginia: U.S.
Geological Survey Geologic Quadrangle Map GQ-190, scale 1:24,000.
Leary, R.M., 1989, Description of the Cumberland Mountain Tunnel Project, in
Dean, C.S., and Moshier, S.O., eds., Cumberland Mountain: The inside story
(guidebook and roadlog for Geological Society of Kentucky 1989 annual
field conference): Kentucky Geological Survey, ser. 11, p. 3–4.
Milam, K.A., and Kuehn, K.W., 2002, The Middlesboro impact structure and
regional geology of the Pine Mountain Thrust Sheet, in Ettensohn, F.R., and
Smath, M.L., eds., Guidebook for geology field trips in Kentucky and adjacent
areas (guidebook for 2002 joint meeting of North-Central Section and
Southeastern Section of the Geological Society of America, Lexington, Ky.):
University of Kentucky, p. 57–73.
Milam, K.A., and Kuehn, K.W., 2003, Field guide to the Middlesboro impact
structure and beyond, in Kuehn, K.W., Milan, K.A., and Smath, M.L., eds.,
Geologic impacts on the history and development of Middlesboro, Kentucky
(guidebook for Kentucky Society of Professional Geologists 2003 annual
field conference): Kentucky Society of Professional Geologists, p. 30–44.
Mullins, J.E., 2003, Spatial database of the Ewing quadrangle, Kentucky-Virginia:
Kentucky Geological Survey, ser. 12, Digitally Vectorized Geologic Quadrangle
Data DVGQ-172. Adapted from Englund, K.J., Smith, H.L., Harris, L.D.,
and Stephens, J.G., 1963, Geology of the Ewing quadrangle, Kentucky and
Virginia: U.S. Geological Survey Geologic Quadrangle Map GQ-172, scale
1:24,000.
National Park Service, 1999a, The Civil War: www.nps.gov/archive/cuga/civilwar.htm
[accessed 03/31/2011].
N a t i o n a l P a r k S e r v i c e , 1 9 9 9 b , T h e C u m b e r l a n d G a p Tu n n e l :
www.nps.gov/archive/cuga/tunnel.htm [accessed 03/31/2011].
Rice, C.L., and Ping, R.G., 1989, Geology of the Middlesboro North quadrangle,
Kentucky: U.S. Geological Survey Geologic Quadrangle Map GQ-1663, scale
1:24,000.
Sparks, T.N., and Lambert, J.R., 2003, Spatial database of the Middlesboro North
quadrangle, Kentucky: Kentucky Geological Survey, ser. 12, Digitally
Vectorized Geologic Quadrangle Data DVGQ-1663. Adapted from Rice, C.L.,
and Ping, R.G., 1989, Geologic map of the Middlesboro North quadrangle,
Kentucky: U.S. Geological Survey Geologic Quadrangle Map GQ-1663,
scale 1:24,000.
Thompson, M.F., 2003, Spatial database of the Middlesboro South quadrangle,
Tennessee-Kentucky-Virginia: Kentucky Geological Survey, ser. 12, Digitally
Vectorized Geologic Quadrangle Data DVGQ-301. Adapted from Englund,
K.J., 1964, Geology of the Middlesboro South quadrangle, TennesseeKentucky-Virginia: U.S. Geological Survey Geologic Quadrangle Map GQ301, scale 1:24,000.
A sandstone chimney is what is left of an old iron furnace at Cumberland
Gap, Tenn. To produce 1 ton of iron, the furnace needed 200 bushels of
charcoal, 2 tons of iron ore, and 500 pounds of limestone (National Park
Service, 1999b). Photo by John Graves.
Acknowledgments
Geologic data were derived from the Kentucky Geological
Survey–U.S. Geological Survey geologic mapping project. Nearly
190 geologists mapped the geology of Kentucky from 1960 to 1978.
KGS geologists converted the resulting 707 geologic quadrangle
maps into digital format as part of the STATEMAP component of
the National Cooperative Geologic Mapping Program of the U.S.
Geological Survey.
We would like to thank Scott Teodorski with Cumberland Gap
National Historical Park and Steven L. Martin, William M. Andrews
Jr., Stephen F. Greb, and Daniel I. Carey with the Kentucky Geological
Survey.
Cartography by Terry Hounshell
For information on obtaining copies of this map and
other Kentucky Geological Survey maps and publications
call:
Public Information Center
(859) 257-3896
Toll free: 1-877-778-7827
View the KGS World Wide Web site at
www.uky.edu/kgs
© 2011, University of Kentucky,
Kentucky Geological Survey