Origin of Lakes II
Lakes Formed By Landslides
Landslides may dam river valleys or leave small
depression at head of slump
Usually caused by abnormal meteorological
events
Frequently temporary - often fail as dam erodes
away
Examples
– Triangle Lake, OR
– Clear Lake, CA
Solution Lakes
Solution lakes are created by depressions in
soluble rock formed by action of percolating
water
Most common in limestone geology
– CaCO3 dissolved by water made acidic by CO2
– Other minerals also vulnerable
NaCl
CaSO4
Ferric and aluminum hydroxides
Solution Lakes
Solution lakes are usually very circular and
conical-shaped
Termed dolines
Plug sometimes releases and drains lake
Usually extend to ground water
Sometimes form catastrophically
Lakes sometimes in caves
Doline
Lakes Formed By Fluvial Action
Plunge pool lakes
Evorsion - forms pot holes
Rate
Examples
– Lakes of the Grand Coulee system, WA
Lakes Formed By Fluvial Action
Lateral lakes
– Fluvial sediments dam tributaries
Deltaic lakes
– Where rivers enter a lake or sea, sedimentation forms
deltas
– Where velocity is reduced, sediments drop out
– Water flows around in a crescent shape
– Open end extends seaward
– Alluvial deposition extends further seaward and lake
forms in depression
Lakes Formed By Fluvial Action
Levee lakes
In floodplains of large rivers, sediments
may be deposited at high flow and leave a
bank or levee
Depression between extreme outer bank
and levee may form lake
Usually parallel to channel
Lakes Formed By Fluvial Action
Oxbow lakes
Formed by meander of river channel
Erosion on outside of channel and deposition
on inside of channel create serpentine pattern
Meander cut off by erosion and subsequent
deposition at high flow
Outer side is deeper
Lake is characteristically U-shaped
Example
–
–
Beaver Lake and Colorado Lakes, Corvallis, OR
Hayden and Humbug Lakes, Independence, OR
Lakes Formed by Wind Action
Dune lakes
Wind redistributes sand
Lakes form in depressions
Often temporary
Examples
– Indiana Dunes of the Great Lakes
Lakes Formed by Wind Action
Deflation basin
Surface sand and soil blown away from
hard pan of rock or clay
Termed playas
Very shallow
Often ephemeral
Playa
Indiana Dunes
Lakes Associated with Shorelines
Irregularities and indentations of
shorelines may be closed-off
Often coastal
Examples
– Siltcoos, Tahkenitch, and Tenmile Lakes, OR
Shoreline
Lakes Formed by Organic Accumulation
Phytogenetic dams
Plant growth may block outlet
Examples
– Lake Okeechobee
– Sphagnum bogs
– Tundra lakes
– Amazon lakes
– Coral atolls
Lakes Formed by Behavior of Higher
Organisms
Beaver dams
Human dams
Dams
Lakes Produced by Meteorite Impact
Examples
– Carolina Bays, SC
– Chubb Lake, Canada
Carolina Bays
Carolina Bays