3a. Galcio-fluvial landforms as a result of climate change

Question 1

What does is a ‘glacio-fluvial’ landform?

Answer 1

landform produced by meltwater (released by seasonal melting or mostly by deglaciation)

Question 2

What effect does post-glacial climate change have?

Answer 2

• temperatures rise
• experience shorter inter-glacial periods
• gradual increase in temperature with many fluctuations
• increase in meltwater

Question 3

What is the distinctive sediment type that glacio-fluvial streams deposit?

Answer 3

outwash

Question 4

What are the main differences between outwash and till?

Answer 4

Outwash is:
- deposited by meltwater (till comes from glacier directly)
- smaller (meltwater has less energy)
- more smooth & rounded (by attrition)
- sorted (largest material found further up valley)
- stratified (in layers)

Question 5

Glacio-fluvial landforms: what are the 2 different types of kames?

Answer 5

• delta kame = a hill/hummock composed of stratified sand & gravel
• kame terrace = ridges of material running along the edge of the valley floor

Question 6

Glacio-fluvial landforms: how is a delta kame formed?

Answer 6

• the mounds of material at the snout of a glacier that build up in height as a glacier melts
• meltwater streams carry material from within and under the glacier to be deposited at the snout of the glacier

Question 7

Glacio-fluvial landforms: how is a kame terrace formed?

Answer 7

• supraglacial streams on edge of glacier transport lateral moraine, which is deposited on the valley floor when the glacier retreats
• streams form due to melting of ice warmed by contact with the valley sides

Question 8

Glacio-fluvial landforms: what is an esker?

Answer 8

long sinuous (curvy) rudge composed of stratified sand and gravel

Question 9

Glacio-fluvial landforms: how is an eskers formed?

Answer 9

• subglacial streams may carry huge amounts of debris under pressure in confined tunnels
• material is deposited in sub-glacial tunnels as supply of meltwater decreases at end of glacial period

Question 10

Glacio-fluvial landforms: what is an outwash plain?

Answer 10

flat expanse of sediment in the proglacial area

Question 11

Glacio-fluvial landforms: how is an outwash plain formed?

Answer 11

• as meltwater streams lose energy, they deposit their load (sorted outwash - heaviest closest to ice)
• these are drained by braided streams

Question 12

Glacio-fluvial landforms: what are braided streams? why are they common in outwash plains?

Answer 12

river channels subdivided into numerous islets and channels
(common in outwash plains due to seasonal fluctuations in meltwater)

Question 13

Glacio-fluvial landforms: how are braided streams formed?

Answer 13

• braided streams lose water at end of melting period so deposit material in the channel, causing it to divide (sorted - coarsest material dropped first then finer, increasing the size of the bar)
• bars exposed at low discharge can be stabilised by vegetation

Question 14

What’s the impact of climate change in eskers and kames?

Answer 14

temps rising –> more retreating glaciers –> more meltwater –> more outwash material –> greater number and length of eskers & kames

Question 15

What’s the impact of climate change on braided streams/outwash plains?

Answer 15

temps increase –> growing season increases –> exposed outwash becomes more colonised over time