Origin of Lakes - Oregon State University

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Origin of Lakes - Oregon State University
Origin of Lakes
Party Facts
Lakes cover 2% of the earth's surface (2.5
x 106 km2)
Largest purely freshwater lake is Lake
Superior (83,300 km2)
Laurentian Great Lakes
A - 245,420 km2
V - 24,620 km3
Lake Baikal
20% of the world's fresh water
World's deepest lake
Maximum depth (zm) – 1620 m
Mean depth (z) – 740 m
V - 23,000 km3
Of 1200 species of animals and 600
species of plants found in Lake Baikal,over
80% of the taxa found in open water are
endemic
Tectonic basins
Lakes formed by volcanic activity
Lakes formed by landslides
Lakes formed by glacial activity
Solution lakes
Lakes formed by fluvial action
Lakes formed by wind
Lakes associated with shorelines
Lakes formed by organic accumulation
Lakes formed by behavior of higher
organisms
Lakes formed by meteorite impact
Tectonic Basins
Depressions formed by movement of
the earth's crust (e.g. warping,
fracturing, faulting, thrusting).
Does not include volcanic activity.
Fort Rock
Single fault displacement
(orogenesis)
Broken fault blocks which may become
slightly and irregularly tilted
Examples
– Abert Lake, OR
– Walker lake, NV
– Lake Winnemucca, NV
Walker Lake
Downfaulted troughs or grabens
(orogenesis)
Elongated area is depressed and lake
lies in bottom depression
Often difficult to distinguish between
single fault deplacement and grabens
– Tule Lake and Lower Klamath Lake are
single fault displacement basins but are
surrounded by lake sediments deposited in
Pleistocene graben lakes
Tule Lake
Downfaulted troughs or grabens
Examples
– Lake Tahoe, CA
Zm - 501 m
– Lake Lahonton
Complex of fault troughs
– Lake Baikal
– Lake Tanganyika
Lake Tanganyika
Uplifted basins (epeirogenesis)
Marine depressions uplifted
Examples
– Lake Okeechobee, FL
Lake Okeechobee
Uplifted basins (epeirogenesis)
Uplifted plains
Examples
– Great Salt Lake
– Lake Victoria
– Lake Titicaca
Altiplano was raised 4000 m during the formation
of the Andes during the Tertiary
Lake Titicaca
Lake Titicaca
Great Salt Lake
Uplifted basins (epeirogenesis)
Subsidence basins
– Often formed by earthquakes
– Often porous, therefore dry
Examples
– Reelfoot Lake, TN
Reelfoot Lake
Reelfoot Lake
Lakes formed by Glacial Activity
Pleistocene glaciation produced more current
lakes than any other process of lake formation
Four major episodes in Northern Hemisphere
– Wisconsin glacier began to retreat 17,000 years ago
and stopped 10,500 years ago
Glaciers begin in mountain ranges and extend in
ice sheets across flatter topography (piedmont
glaciers)
Glacial Lakes
Glaciers
Pleistocene Glaciers
Morainal Deposits
Lakes associated with active glaciers
Lakes form on, within, beneath, and below
thawing glaciers
Examples
– Laurentian Great Lakes
Lakes on Glaciers
Ice scour lakes
Ice moving over fractures removes rubble
along fracture
Examples
– Diamond Lake, OR
– Crescent Lake, OR
– Waldo Lake, OR
– Odell Lake, OR
Waldo Lake
Odell Lake
Cirque lakes (or tarns)
Formed in upper portions of glaciated valleys
of mountainous areas by repeated freezing
and thawing action
Amphitheatre-shaped
Water held behind rock or morainal sill
Generally small and relatively shallow (<50m)
Often one above another - "hanging" lakes
Examples
– Grinnel Lake in Glacier National Park
– Bull Run Lake, OR
– Aneroid Lake, OR
Cirque Lakes
Cirque Lakes
Upper Bull Run Lake
Lakes below snow line
Paternoster lakes
– Corrosive action of ice forms chains of rock
basins within glacial valley
Examples
– Glacier National Park
– Yosemite National Park
– Bighorn Mountains, WY
Glacial Trough
Paternoster Lakes
Lakes below snow line
Fjord lakes
– Low elevations
– Long, narrow lakes in deep, steep-sided
valleys
Examples
– Kootenay Lake, B.C.
– Lake Okanagan, B.C.
– English Lake District
Fjord Lakes
Fjord Lake
Loch Ness
Loch Ness
Lakes below snow line
Piedmont lakes
– Low elevation
– Glacial scouring in weak areas of parent
geologic material
Examples
– Great Slave Lake
– Great Bear Lake
– Great Lakes of St. Lawrence drainage
Lakes formed by morainal deposits
Lateral morainal dams
– Moraine deposited across the mouth of tributaries
– More V-shaped
– Examples
Finger Lakes of New York
Finger Lakes
Finger Lakes
Finger Lake
Lakes formed by morainal deposits
Terminal morainal deposits
– Moraine left behind retreating glacier with
corrosion
– More U-shaped
– Examples
Wallowa Lake, OR (also associated with lateral
moraines)
Flathead Lake, MT
Wallowa Lake
Wallowa Lake
Lakes formed in ground moraine
Deposition of meltwater outwash
Drift left behind with blocks of ice mixed in
Kettle lakes form where ice blocks melted
– Very irregular in shape, slope, and
topography
– Generally shallow (<50 m)
– Examples
Walden Pond
Trout Lake
Walden Pond - Kettle Lake
Morainal Deposits and Kettle Lakes
Kettle Lake Forming
Lakes formed from effects of permafrost
Cryogenic lakes - formed by effect of
frozen ground coalesce and forms larger
lakes - thermokarst lakes
Volcanic Activity
Granitic or basaltic nature of parent
material causes low concentrations of
nutrients and, therefore, low productivity
Crater Lakes
Cinder cones
– Small, conical lakes
Examples
– Crater Butte Lake in Mount Lassen National
Park, CA
Maars
Created by explosive eruption of lava
coming in contact with groundwater or
degassing of magma
– Circular and very deep
– Small - b< 2km
Examples
– Lakes in Eifel district of Germany
– Big Soda Lake, NV
Calderas
Created by subsidence of the roof of a
partially emptied magma chamber
Usually larger than maars
Examples
– Crater Lake, OR
Second deepest lake in North America
Seventh deepest lake in the world
Collapse of peak of Mount Mazama in 4500 B.C.
A - 64 km2
Zm - 608.4 m
Crater Lake
Crater Lake
Lava Flow Lakes
Coulee Lakes - Depression formed by collapse
when overlying layers of a lava flow hardens and
underlying layers continue to flow and leave
voids
Irregular lava flows
– Examples
Yellowstone Lake
Damming by lava flows
– Examples
Clear Lake, OR
Yellowstone Lake
Yellowstone Lake
So What?
Does this stuff make any
difference?

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