glaciers, glacio fluvial

Question 1

what are characteristics of glacio fluvial deposits

Answer 1

• smaller than glacial till
• more rounded (contact with water)
• vertical layers or stratified - reflect annual or seasonal deposits
• sorted horizontally or graded

Question 2

how are kames formed

Answer 2

• meltwater stream plunge into crevasses
• accumulation of material in crevasses which are left behind as ice melts
• unsupported - collapse when ice retreats
• can be few hundred metres long and tens of metres high

Question 3

example of kames

Answer 3

East lothian - scotland

Question 4

what are kames terraces?

Answer 4

• flat topped ridges with sorted material along the edge of the valley

Question 5

how are kame terraces formed

Answer 5

• surface meltwater streams plunge down side of glacier and valley wall

Question 6

example of kame terraces

Answer 6

Columbia icefield

Question 7

how are kame deltas formed

Answer 7

• as englacial /supraglacial streams emerge at snout of glacier, loosing energy
• deposits load on entering ice marginal lakes

Question 8

examples of kame deltas

Answer 8

• east lothian, scotland

Question 9

what are eskers

Answer 9

• long sinuous (bendy) ridges of land composed of sands and gravel

Question 10

formation of eskers

Answer 10

• meltwater streams follow tunnels beneath melting glacier
• can carry debris whilst under pressure
• deposition happens in tunnels where streams loose energy
• speed of deposition and retreat changes form beaded esker

Question 11

example of esker

Answer 11

Trim esker near Dublin

Question 12

what are outwash plains

Answer 12

a flat expense of sediment in the proglacial area

Question 13

formation of outwash plain

Answer 13

• meltwater streams gradually loose energy in lowland areas
• largest and coarsest pieces dropped first

Question 14

typical characteristics of outwash plains

Answer 14

• stratified, graded, rounded deposits
• often have braided streams
• kettles / kettle lakes are often found here

Question 15

kettle hole formation

Answer 15

• as glacier retreats and large blocks of ‘dead ice’ from main glacier goes onto outwash plain
• sediment builds around it
• when it melts there is a big depression (gap) called kettle
• if it fills with water, it becomes a kettle lake

Question 16

what are braided streams

Answer 16

• these form on the outwash plain where channels of meltwater become clogged by coarse deposits, encouraging stream to divide into smaller streams

Question 17

how are braided streams formed

Answer 17

• streams on outwash plain loose energy
• material will be deposited in the channel
• river divides around the material (eyeot) and then rejoins
• at discharge, channel bars might be stabilised and grow vegetation

Question 18

how are braided streams formed

Answer 18

• streams on outwash plain loose energy
• material will be deposited in the channel
• river divides around the material (eyeot) and then rejoins
• at discharge, channel bars might be stabilised and grow vegetation

Question 19

why are glacio fluvial deposits difficult to identify

Answer 19

• repeated advance and retreat will modify appearance
• can weather, erode or gain vegetation after ice is gone
• some landforms are excavated for their sands and gravel
• rising temp, more melting, more spread out deposits of outwash material
• increase temp vegetation grows