fluvioglacial landforms

Question 1

what are fluvioglacial landscapes

Answer 1

landscapes formed by fluvioglacial processes (associated with flowing water)
-meltwater flows from under glacier snout

Question 2

process of water movement

Answer 2

-huge amount of water trapped beneath ice - eventually bursts (glacial outburst)
-can flow on top (supra), within (en), or under (subglacial)

Question 3

difference between glacial deposits and fluvioglacial deposits

Answer 3

-G = unstratisfied, difficult to identify layers FG = stratified and layers due to seasonal variations in sediment accumulation
- G = unsorted as ice melts and leaves it all FG = sorted - meltwater loses energy and deposits heavier first
- G = material angular, various shapes and sizes (from physical weathering and erosion. FG = smooth and round (from attrition), sorted and graded

Question 4

Eskers (ice contact features)

Answer 4

long winding ridges of sand and gravel, up to 30m high, several km long
-lung parallel to valley sides
-formed by sub glacial river deposition during final stages of glacial period as glacier retreats
- imagine sub glacial river gets blocked, then glacier melts

Question 5

kames (ice contact features)

Answer 5

mounds of till which show some evidence of meltwater flow
-kames form when sand and gravel are deposited by stream in final stages of glacial period - form on ice surface initially
- kame terraces, deltas, and crevasse kames

Question 6

kame terraces (ice contact features)

Answer 6

• result from infilling of a marginal glacial lake
  -when ice melts, kame terrace is left as ridge on valley side

Question 7

kame deltas (ice contact features)

Answer 7

• smaller features that form when stream deposits material on entering marginal lake
  -forms a small, mound like hills on valley floor

Question 8

crevasse kames (ice contact features)

Answer 8

small hummocks deposited on valley floor as result of sediment deposited in surface crevasses

Question 9

outwash plain/Sandur (pro-glacial feature)

Answer 9

-an extensive, gently sloping area of sands and gravel that forms in front of glacier
-results from outwash of materail carried by meltwater streams and rivers
-during glacial period, meltwater and material deposited limited to summer so at end of glacial period, huge quantities of material spread out over outwash plain by great torrents of meltwater

Question 10

pro glacial lakes (pro-glacial feature)

Answer 10

-when ice sheets expand and dams rivers, creates pro glacial lakes
-when ice sheet retreats - lake empties - deep gorges formed

Question 11

meltwater channel (pro-glacial feature)

Answer 11

-overflow of lake creates these channels
-a deep narrow, steep sided and flat floored valley

Question 12

kettle holes (pro-glacial feature)

Answer 12

• form when large blocks of ice (left behind when glacier retreats) are covered by deposits from meltwater streams
  -when ice melts, depression left behind, fills with water to form kettlehole