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A-level Geography New Required Spec > EQ3- Glaciation > Flashcards

EQ3- Glaciation Flashcards

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1
Q

Freeze thaw weathering

A
  • Water enters cracks in the day with precipitation
  • but freeze overnight when temps fall below 0 + expand 9% volume
  • repetition causes breaking of rock
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2
Q

Glacial plucking (quarrying)

A
  • Underneath glacier meltwater gets into cracks+ freezes
  • ice attached + ‘locks’ itself to rock
  • as ice moves forward pulls out rock
  • loose rock is now found as bedrock
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3
Q

Glacial abrasion

A

Sand papering effect of ice as it grinds over + scours landscape

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4
Q

Formation of a Corrie(cirque)

A
  • snow builds up in hollow high up on N face mountain sides (less sun)
  • yr later small glacier forms
  • ice moves under own weight circular way ROTATIONAL MOVEMENT
  • small Corrie full ice flows into main valley glacier
  • mountain top weathered by FREEZE-THAW persistent freezing+ melting breaks sediment off fall into ice
  • erosion back wall caused PLUCKING water freezes+ pulls off rock - develops vertical jagged appearance
  • rocks fallen into glacier ice scrape away floor by ABRASION- deep bowl shape formed
  • less erosion front Corrie as ice thinner so lip/ rock bar forms also moraines formed here
  • when ice melts small but v deep lake often forms hollow called tarn
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5
Q

Formation arête

A
  • Plucking and abrasion on back wall 2 corries on mountainside mean they erode backwards towards each other creating a narrow ridge
  • +freeze thaw important
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6
Q

Formation pyramidal peak

A
  • Plucking (especially) + abrasion on 3+ corries erode backwards create
  • sharp pointed mountain summit
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7
Q

Formation glacial trough

A
  • v-shaped valley widened+ deepened by powerful plucking+ abrasion valley glacier goes thru landscape
  • create u-shaped valley w/steep sides+ wide, flat floor
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8
Q

Formation Hanging valley

A
  • Powerful thicker glacial ice in main glacial trough eroded vertically downwards more rapidly than thinner ice/ rivers tributary valley
  • create small tributary (v/u) valley high above main glacial trough often w waterfall
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9
Q

Formation Truncated spur

A
  • Valley glaciers less flexible than rivers + remove ends interlocking spurs by plucking+ abrasion as move down river valley
  • steep rocky valley side (where spurs river used to interlock)
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10
Q

Formation Ribbon lake

A
  • areas increased plucking+ abrasion by valley glacier deepen part of valley floor cos of confluence glaciers/ weaker rocks
  • create long, narrow lake along floor glacial trough
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11
Q

Formation Roche mountonnée (ice sheet scouring)

A
  • bare outcrop rock on valley floor sculpted moving ice
  • stoss end increased pressure due resistance outcrop moving ice caused localised pressure melting as PMP reached
  • leads basal slip w/ regelations, abrasion+ polishing creating striations+ chatter marks
  • lee end reduced pressure caused meltwater freeze forming bond between rocky outcrop+ overlying ice
  • leading plucking+ lots mechanical weathering(freeze thaw) creating jagged, craggy appearance
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12
Q

Formation crag+ tail (ice sheet scouring)

A
  • where hard rock provides ‘pressure shadow’ on lee side resulting soft rock behind eroded less
  • but before crag softer rock eroded+ sediment deposited shadow zone (lee side) forming tail deposited material (till)
  • e.g. Edinburgh castle on igneous rock w/ softer limestone around it forming tail to L
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13
Q

Formation of knock +Lochan (ice sheet scouring)

A
  • glacially scoured lowland areas when ice sheets+ glaciers (typically temperate) expand out beyond constrained mountain valleys
  • eroding beneath (subglacial) landforms different rates depending rock types
  • displaying alternating roche moutonnées: more resistant rock (KNOCK)+ areas eroded hollows (often containing small lakes) less resistant rock/ lots cracks, fractures+ joints (LOCHANS)
  • e.g. NW highlands, Scotland
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14
Q

Formation medial moraine (ice contact, depositional)

A
  • 2 valleys converge 2 lateral moraines combine to form
  • material carried+ deposited when melting occurs parallel ice flow
  • form ridge moraine down middle valley flood
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15
Q

Formation lateral moraine (ice contact, depositional)

A
  • exposed rock on valley side weathered+ fragments fall down onto edge glacier
  • then carried along valley+ deposited when ice melts parallel ice flow
  • form ridge moraine along edge valley floor
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16
Q

Formation terminal/end moraine (ice contact, depositional)

A
  • advancing ice carries moraine forward+ deposits at pt max advance when retreats
  • up-valley (ice contact) side generally steeper than other side as advancing ice rose over debris
  • transverse ice flow
  • forms ridge moraine extending across valley at furthest pt glacier reached
17
Q

Formation drumlins (ice contact, depositional)

A

-example equifinality unsure about formation
-surge theory: suggest surging glacier deposits excess till that carrying at base, as some consist (at least partly) glacial till
-Boulton-Menzies theory: suggests deposition in lee of slowly moving obstacle in deforming layer, obstacle of bedrock/thermally frozen material forms core drumlin+ ground moraine plastered around
-Shaw theory: suggests subglacial meltwater in flood caused irregularities form in river bed which moulded into drumlins+ streamlined by advancing ice
(rounded mounds parallel ice flow w/ broad upstream end (stoss)+ tapered downstream end (lee))

18
Q

Formation Recessional moraine (ice contact, depositional)

A
  • each represent still-stand during ice retreat (gd indicator cycle advance+ retreat)
  • transverse ice flow
  • series ridges running across valley behind terminal moraine
19
Q

Formation till plains (lowland depositional landscape)

A
  • sheet ice retreating deposits lrg amounts material over sizeable area
  • form lrg, relatively flat plain/ undulating landscape till
  • e.g. ground moraine
20
Q

Formation lodgement till (lowland depositional landscape)

A
  • actively moving ice deposits till lodged/ pressed into valley floor beneath glacier
  • forming deposits angular rock fragments in fine matrix- unstratified, unsorted + containing erratics
  • e.g. Drumlins
21
Q

Formation of ablation till (lowland depositional landscape)

A
  • stationary/ retreating glaciers deposit till by melting ice
  • forming (same lodgement) deposits angular rock in fine matrix- unstratified, unsorted + containing erratics
  • e.g. terminal+recessional moraines
22
Q

Mass movement

A
  • Downslope movement of material (rock+soil) under force of gravity
  • term for wide range specific movements e.g. landslides, rotational movement+ block fall
23
Q

Basal melting

A
  • When melting point water decreases under pressure thus water melts at lower temps under thicker glaciers
  • can lead to basal sliding where glacier ‘floats’ above layer meltwater (acts as lubricant) therefore the glacier can move faster

A-level Geography New Required Spec (20 decks)

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