g110 13 glacial geology depos
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Paths of Glacial TransportPaths of Glacial Transport
Supraglacial all the waySupraglacial all the way
Supraglacial to englacialSupraglacial to englacialto supraglacialto supraglacial
Subglacial all the waySubglacial all the way Subglacial to englacialSubglacial to englacial
to supraglacialto supraglacial
Which path will have theWhich path will have the
greatest effect ongreatest effect onabrasion of transportedabrasion of transportedclasts?clasts?
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Types of Glacial DepositsTypes of Glacial Deposits
DriftDrift: all deposits in any way related to: all deposits in any way related toglaciation.glaciation.
TillTill: unstratified drift carried and: unstratified drift carried anddeposited by the ice.deposited by the ice.
Stratified driftStratified drift: water has played a role in: water has played a role indeposition.deposition.Types are:Types are: Glaciofluvial:Glaciofluvial: by meltwater streamsby meltwater streams
Glaciolacustrine:Glaciolacustrine: in glacial lakesin glacial lakes Glaciomarine:Glaciomarine: in the oceanin the ocean
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Types of TillTypes of Till -- ProcessesProcesses
Lodgement TilllLodgement Tilll FlowFlowTillTill
Lodgement till and subglacialLodgement till and subglacialflow till.flow till.
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Depositional LandformsDepositional Landforms
MorainesMoraines
Moraines without ridgelike form:Moraines without ridgelike form:
ground moraineground moraine
flat to rolling, hummocky terrainflat to rolling, hummocky terrain
predominantly lodgment tillpredominantly lodgment tilloverlain by ablation tilloverlain by ablation till
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Note areaNote area
of groundof groundmorainemoraine(GM)(GM)
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Note groundNote groundmorainemoraine
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Depositional LandformsDepositional Landforms
Moraines (cont.)Moraines (cont.)
Moraines without ridgelike form:Moraines without ridgelike form:
disintegration morainedisintegration moraine::
moderately rugged terrain ofmoderately rugged terrain ofchaotic mounds and pits (chaotic mounds and pits (kameskames andand kettles)kettles)formed by the downwasting offormed by the downwasting of
stagnant icestagnant ice
sediments a mixture of ablation till, glaciofluvialsediments a mixture of ablation till, glaciofluvialdeposits, and glaciolacustrine deposits.deposits, and glaciolacustrine deposits.
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NoteNote
disintegrationdisintegrationmorainemoraine..
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Note disintegration moraine in right halfNote disintegration moraine in right halfof area.of area.
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Depositional LandformsDepositional Landforms
Moraines (cont.)Moraines (cont.)moraines with ridgemoraines with ridge--like formlike form
lateral moraineslateral moraines andand medialmedial
moraines (alpine terrain)moraines (alpine terrain) most prominent where the valley is notmost prominent where the valley is not
too restrictivetoo restrictive
debris from within the glacier due todebris from within the glacier due tolaterallateral flow or may be massflow or may be mass--wastedwasted
How would the latter be related toHow would the latter be related to slopeslope
aspect?aspect?
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Note lateralNote lateralmoraine.moraine.
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Depositional LandformsDepositional Landforms
Moraines (cont.)Moraines (cont.)
medial moraines:medial moraines:
form from the merger of two alpine glaciers andform from the merger of two alpine glaciers and
their lateral morainestheir lateral moraines
traced downglacier, often merge with a cover oftraced downglacier, often merge with a cover of
ablation till resting on the iceablation till resting on the ice
rarely preserved when the ice melts. Why wouldrarely preserved when the ice melts. Why would
that be?that be?
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Medial Moraines
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Depositional LandformsDepositional LandformsMoraines (cont.)Moraines (cont.)
end moraine: terminal moraine:end moraine: terminal moraine:any moraine builtany moraine built marks outermostmarks outermost
around the marginaround the margin advance of glacieradvance of glacierof a glacier.of a glacier. during aduring a
particular glacialparticular glacialrecessional morainerecessional moraine stage (onlu onestage (onlu onemarks position ofmarks position of terminal moraine canterminal moraine can
pauses or readvancespauses or readvances exist).exist).
during time of overallduring time of overall
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Note end and
Note end andlaterallateral
moraines.moraines.
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NoteNote
terminalterminalmorainemoraineandandrecess.recess.morainemoraine
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Note terminal and recessionalNote terminal and recessional
morainesmoraines..
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Streamlined FormsStreamlined Forms
DrumlinsDrumlins Elliptically elongated hills parallel to flowElliptically elongated hills parallel to flowdirection.direction.
Dimensions of < 150 ft high, 1/3 to 1/2Dimensions of < 150 ft high, 1/3 to 1/2
milemile long.long. Blunt end upglacier, tapered downglacier.Blunt end upglacier, tapered downglacier.
Composed mostly of till, but may haveComposed mostly of till, but may havecorecore of bedrock, waterlaid materialof bedrock, waterlaid material
(deformed)(deformed)
Usually located several miles back fromUsually located several miles back from
icemargin in clusters. Why?icemargin in clusters. Why?
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NoteNote
drumlins.drumlins.(DR).(DR).
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NoteNotedrumlinsdrumlins
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Glaciofluvial DepositsGlaciofluvial DepositsProcesses of DepositionProcesses of Deposition
Deposition either:Deposition either:
In direct contact (iceIn direct contact (ice--contact)contact) with the icewith the ice or some distance beyond the ice (or some distance beyond the ice (proglacialproglacial))
Processes of fluvial deposition mostProcesses of fluvial deposition mostcommoncommon
Sometimes flow is in tunnels or otherSometimes flow is in tunnels or otheropenings in the ice where water may beopenings in the ice where water may beunder pressure.under pressure.
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Glaciofluvial DepositsGlaciofluvial Deposits
Distinguishing CharacteristicsDistinguishing Characteristics Clasts roundedClasts rounded
Usually unimodal grain size (fines removed)Usually unimodal grain size (fines removed) Bedding, some rather crudeBedding, some rather crude
Often crossOften cross--beddedbedded
GrainGrain--toto--grain contactgrain contact
Imbrication possible, may reveal flow dir.Imbrication possible, may reveal flow dir.
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IceIce--Contact LandformsContact LandformsConsiderations andConsiderations and
CharacteristicsCharacteristics
Ice on at least one sideIce on at least one side
Extreme range and abrupt changes inExtreme range and abrupt changes ingrain sizegrain size
Clasts less abraded than in proglacialClasts less abraded than in proglacialdepositsdeposits
May include bodies of tillMay include bodies of till Slumping commonSlumping common
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Glaciofluvial IceGlaciofluvial Ice--ContactContactLandformsLandformsKame TerracesKame Terraces
Short, narrow benches along valley wall ofShort, narrow benches along valley wall ofglaciated valleys.glaciated valleys.
Surface often pitted with kettles.Surface often pitted with kettles. Accumulations of streams that flowedAccumulations of streams that flowed
between glacier and valley wall.between glacier and valley wall. Ice usually stagnant.Ice usually stagnant. Left as terraces when ice melted.Left as terraces when ice melted.
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NoteNotekame terrackame terrac(KT)(KT) andandkames (K)kames (K)
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Note kame terrace (KT)Note kame terrace (KT)and kames (K).and kames (K).
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Glaciofluvial IceGlaciofluvial Ice--ContactContact
LandformsLandformsKamesKames Moundlike hill.Moundlike hill.
Formation may be as sediment is deposited inFormation may be as sediment is deposited increvasses in or on the surface of stagnant ice.crevasses in or on the surface of stagnant ice.
Or, where small deltas or fans build against theOr, where small deltas or fans build against theice.ice.
Debris collapses to form mound when ice melts.Debris collapses to form mound when ice melts. May be found in kameMay be found in kame--andand--kettle moraines.kettle moraines.
See previous illlustrations.See previous illlustrations.
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Glaciofluvial IceGlaciofluvial Ice--ContactContact
LandformsLandforms --EskersEskers
Long, narrow commonly sinuous ridges.Long, narrow commonly sinuous ridges.
May connect downvalley with deltas.May connect downvalley with deltas.
Overall trend parallels the direction of iceOverall trend parallels the direction of iceflow.flow.
May climb over low ridges. How can it be?May climb over low ridges. How can it be? Slumping may occur along sides.Slumping may occur along sides.
Mostly sand & gravel, but with lenses ofMostly sand & gravel, but with lenses oftill.till.
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Glaciofluvial IceGlaciofluvial Ice--ContactContact
LandformsLandformsEskers (cont.)Eskers (cont.)
They are deposits of streams inThey are deposits of streams intunnels. Probably stagnant icetunnels. Probably stagnant ice
Can you reconstruct what it was likeCan you reconstruct what it was like
when the glacier was forming?when the glacier was forming?
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Note esker.Note esker.Note esker.Note esker.
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NoteNoteeskeresker
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NoteNote
esker.esker.(E).(E).
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Proglacial LandformsProglacial LandformsCharacteristicsCharacteristics
Composed of outwash; coarseComposed of outwash; coarse--grainedgraineddeposits of streams beyond the icedeposits of streams beyond the icemargins.margins.
Usually the deposits of braided streams.Usually the deposits of braided streams.
WellWell--sorted to poorlysorted to poorly--sorted.sorted.
Many variations in grain size, but generallyMany variations in grain size, but generallya decrease downstream.a decrease downstream.
Silt, clay minor or absent.Silt, clay minor or absent. Rounding of clasts, especially boulders andRounding of clasts, especially boulders and
cobbles.cobbles.
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ProglaccialOutwashProglaccialOutwash
FeaturesFeaturesOutwash PlainsOutwash Plains vs.vs. Valley TrainsValley Trains
ConsiderableConsiderablelateral extentlateral extent
Usually in lowlandsUsually in lowlands
Banked against endBanked against endof glacierof glacier
May be fanMay be fan--shapedshaped
Confined by valleyConfined by valleywallswalls
Long and linear orLong and linear or
sinuoussinuous
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NoteNote
autwashautwashplain (OP)plain (OP)and kettlesand kettles(KL).(KL).
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Note disintegration moraine in right halfNote disintegration moraine in right halfof area. Note outwash plain and kettles.of area. Note outwash plain and kettles.
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OutwashOutwashplain is aplain is avvalleyvvalley
train.train.
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Glaciolacustrine FeaturesGlaciolacustrine Features
GlacialLakesGlacialLakes
In erosional basins: cirques (tarns),In erosional basins: cirques (tarns),
rock basins in glacial troughs, etc.rock basins in glacial troughs, etc. Behind morainesBehind moraines
Kettle lakesKettle lakes
Any more?Any more?
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Glaciolacustrine FeaturesGlaciolacustrine Features
KettlesKettles
Basin where ice block was surroundedBasin where ice block was surroundedby sediments.by sediments.
Occur singly or in groups.Occur singly or in groups.
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GlacialG
lacial--Lake SedimentsLake Sediments Delta: coarse sediments, steep crossDelta: coarse sediments, steep cross--
beddingbedding
Bottom deposits: mostly silt and clay;Bottom deposits: mostly silt and clay;usually laminated, may be varved. Whatusually laminated, may be varved. Whatare varves?are varves?
M
ay include dropstonesM
ay include dropstones Shore features: waveShore features: wave--cut cliffs, beachcut cliffs, beachdeposits, etc.deposits, etc.
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Note proglacialNote proglaciallake and kettlelake and kettlelakes.lakes.
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Note outwash plain, kettles,Note outwash plain, kettles,and proglacial lake.and proglacial lake.
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Terms needed for the
study of glacial geologyAbrasion
Arete
CirqueCirque aspect
Col
Drift
Dropstone
Drumlin
End moraine
Esker
Flow till
FacetGlacial lake
Glacial steps
Glaciofluvial
Glaciolacustrine
Glaciomarine
Grooves
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Terms needed for the
study of glacial geologyIce-contact deposit
Ice-push moraine
KameKame terrace
Kettle
Lateral moraine
Lodgment till
Medial moraine
Megagroove
Melt-out till
Nivation hollow
Outwash
Outwash plainPater noster lakes
Polish
Proglacial deposits
Proglacial lake
Recessional moraine
Regelation
Roche moutonee
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Terms needed for the
study of glacial geologyRock basin
Rock drumlin
Rock flour
Stratified drift
Striations
Tarn
Terminal moraine
Till
Valley train
Whaleback
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Student Responsibilities on
Glacial Geology
Know the processes of glacial erosion andKnow the processes of glacial erosion and
the features they produce. Especiallythe features they produce. Especiallyfocus on glacial landforms of alpinefocus on glacial landforms of alpineareas, such as glacial troughs andareas, such as glacial troughs andcirques. Know about the different typescirques. Know about the different types
of glacial deposits and depositionalof glacial deposits and depositionallandforms. Especially focus on moraineslandforms. Especially focus on morainesof various types and glaciofluvial andof various types and glaciofluvial andglaciolacustrine depositsglaciolacustrine deposits..
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