Origin of Lakes IIOrigin of Lakes II

Lakes Formed By LandslidesLakes Formed By LandslidesLandslides may dam river valleys or leave small Landslides may dam river valleys or leave small depression at head of slumpdepression at head of slumpUsually caused by abnormal meteorological Usually caused by abnormal meteorological eventseventsFrequently temporary Frequently temporary -- often fail as dam erodes often fail as dam erodes awayawayExamplesExamples–– Triangle Lake, ORTriangle Lake, OR–– Clear Lake, CAClear Lake, CA

Solution LakesSolution LakesSolution lakes are created by depressions in Solution lakes are created by depressions in soluble rock formed by action of percolating soluble rock formed by action of percolating waterwaterMost common in limestone geologyMost common in limestone geology–– CaCOCaCO33 dissolved by water made acidic by COdissolved by water made acidic by CO22

–– Other minerals also vulnerableOther minerals also vulnerableNaClNaClCaSOCaSO44

Ferric and aluminum hydroxidesFerric and aluminum hydroxides

Solution LakesSolution Lakes

Solution lakes are usually very circular and Solution lakes are usually very circular and conicalconical--shapedshapedTermed Termed dolinesdolinesPlug sometimes releases and drains lakePlug sometimes releases and drains lakeUsually extend to ground waterUsually extend to ground waterSometimes form catastrophicallySometimes form catastrophicallyLakes sometimes in cavesLakes sometimes in caves

DolineDoline

Lakes Formed By Fluvial ActionLakes Formed By Fluvial Action

Plunge pool lakesPlunge pool lakesEvorsionEvorsion -- forms pot holesforms pot holesRateRateExamplesExamples–– Lakes of the Grand Coulee system, WALakes of the Grand Coulee system, WA

Lakes Formed By Fluvial ActionLakes Formed By Fluvial Action

Lateral lakesLateral lakes–– Fluvial sediments dam tributariesFluvial sediments dam tributaries

Deltaic lakesDeltaic lakes–– Where rivers enter a lake or sea, sedimentation forms Where rivers enter a lake or sea, sedimentation forms

deltasdeltas–– Where velocity is reduced, sediments drop outWhere velocity is reduced, sediments drop out–– Water flows around in a crescent shapeWater flows around in a crescent shape–– Open end extends seawardOpen end extends seaward–– Alluvial deposition extends further seaward and lake Alluvial deposition extends further seaward and lake

forms in depressionforms in depression

Lakes Formed By Fluvial ActionLakes Formed By Fluvial Action

Levee lakesLevee lakesIn floodplains of large rivers, sediments In floodplains of large rivers, sediments may be deposited at high flow and leave a may be deposited at high flow and leave a bank or leveebank or leveeDepression between extreme outer bank Depression between extreme outer bank and levee may form lake and levee may form lake Usually parallel to channelUsually parallel to channel

Lakes Formed By Fluvial ActionLakes Formed By Fluvial Action

Oxbow lakesOxbow lakesFormed by meander of river channelFormed by meander of river channelErosion on outside of channel and deposition Erosion on outside of channel and deposition on inside of channel create serpentine patternon inside of channel create serpentine patternMeander cut off by erosion and subsequent Meander cut off by erosion and subsequent deposition at high flowdeposition at high flowOuter side is deeperOuter side is deeperLake is characteristically ULake is characteristically U--shapedshapedExampleExample–– Beaver Lake and Colorado Lakes, Corvallis, ORBeaver Lake and Colorado Lakes, Corvallis, OR–– Hayden and Humbug Lakes, Independence, ORHayden and Humbug Lakes, Independence, OR

Lakes Formed by Wind ActionLakes Formed by Wind Action

Dune lakesDune lakesWind redistributes sand Wind redistributes sand Lakes form in depressions Lakes form in depressions Often temporaryOften temporaryExamplesExamples–– Indiana Dunes of the Great LakesIndiana Dunes of the Great Lakes

Lakes Formed by Wind ActionLakes Formed by Wind Action

Deflation basinDeflation basinSurface sand and soil blown away from Surface sand and soil blown away from hard pan of rock or clayhard pan of rock or clayTermed playasTermed playasVery shallowVery shallowOften ephemeralOften ephemeral

PlayaPlaya

Indiana DunesIndiana Dunes

Lakes Associated with ShorelinesLakes Associated with Shorelines

Irregularities and indentations of Irregularities and indentations of shorelines may be closedshorelines may be closed--offoffOften coastalOften coastalExamplesExamples–– SiltcoosSiltcoos, , TahkenitchTahkenitch, and , and TenmileTenmile Lakes, ORLakes, OR

ShorelineShoreline

Lakes Formed by Organic AccumulationLakes Formed by Organic Accumulation

PhytogeneticPhytogenetic damsdamsPlant growth may block outletPlant growth may block outletExamplesExamples–– Lake OkeechobeeLake Okeechobee–– Sphagnum bogsSphagnum bogs–– Tundra lakesTundra lakes–– Amazon lakesAmazon lakes–– Coral atollsCoral atolls

Lakes Formed by Behavior of Higher Lakes Formed by Behavior of Higher OrganismsOrganisms

Beaver damsBeaver dams

Human damsHuman dams

DamsDams

Lakes Produced by Meteorite ImpactLakes Produced by Meteorite Impact

ExamplesExamples–– Carolina Bays, SCCarolina Bays, SC–– Chubb Lake, CanadaChubb Lake, Canada

Carolina BaysCarolina Bays

Carolina BaysCarolina Bays