OCR A Level GL - 12 OCR A Level GL 2.3a Glacio-fluvial landforms and processes 2

Question 1

What does glacio-fluvial mean?

Answer 1

erosion or deposition caused by flowing meltwater, from melting glaciers, ice sheets and ice caps. ​

Question 2

What characteristics does glacial meltwater have?

Answer 2

it is usually very rich in sediment, which increases its erosive power

Question 3

What are the 3 main glacio-fluvial landforms?

Answer 3

1. Sandars (also known as outwash plains) ​ 2. Kames ​ 3. Eskers

Question 4

When are glacio-fluvial landforms created?

Answer 4

glacio-fluvial landforms are produced by meltwater from glaciers during de-glaciation.​ These meltwater streams often flow at high velocity.

Question 5

What are the characteristics of all glacio-fluvial landforms?

Answer 5

1. Smaller material carried by meltwater streams with less energy than ice​
2. Smooth and rounded particles​
3. Sorted, with larger material further up the valley​
4. Stratified vertically with distinct seasonal and annual layers​

Question 6

What are kames?

Answer 6

rounded mounds/hills of glacio-fluvial deposits.

Question 7

Where are kames formed?

Answer 7

near the end of the former glacier as it begins to retreat.

Question 8

How do kames form?

Answer 8

1. Meltwater held back by terminal moraine leads to the formation of lakes​
2. Material is deposited where the melt water left the glaciers to flow into lakes - creating delta-like landforms. ​
3. When the ice supporting the up-valley side melts, the material collapses back to form the kame.

Question 9

What is another way kames form?

Answer 9

1. Hollows on the surface of a melting glacier fill up with sediment and then gradually go down to lower levels as the ice melted
2. This ultimately forms a mound on the ground surface.

Question 10

What are eskers?

Answer 10

winding/sinuous ridges of coarse sands and gravels that are deposited by meltwater as it flowed in a channel beneath the glacier.

Question 11

How are eskers formed?

Answer 11

-during glaciation englacial and subglacial meltwater streams create tunnels through glacier
-streams carry sand and gravel
-as material is deposited natural sorting takes place
-ice melts leaving snake like features of sediment which follow the path of meltwater stream

Flow is under pressure (hydrostatic pressure) and much material is carried, to be dropped when meltwater reduces (reduction in capacity) in winter and exposed when the glacier melts.

​ Material could have been deposited as the sub-glacial streams become blocked, and material builds up behind this obstacle. The ice then melts to reveal the esker.

​ Alternatively, material is deposited as the sub-glacial stream leaves the confines of the glacier and immediately deposits due to a reduction of capacity due to the lack of hydrostatic pressure.

​ Beaded eskers are formed where there are seasonal changes in the amount of load deposited and therefore form hillocks strung out at intervals.

​ Material is rounded due to water erosion (attrition).

Question 12

What is the common range of height of an esker?

Answer 12

Eskers are often between 5-20m high

Question 13

What is the common range of widths of an esker?

Answer 13

generally between 20-200m wide

Question 14

How long can eskers be?

Answer 14

they can range in length from hundreds of metres to 400km

Question 15

What are sandurs/outwash plains?

Answer 15

Areas that contain deposits from meltwater streams in front of the snout of glaciers.

Question 16

How are sandurs/outwash plains formed?

Answer 16

When meltwater emerges from the snout, it loses its energy as it is no longer flowing under hydrostatic pressure. Consequently, the material it is carrying is deposited - the largest first often forming an alluvial fan at the end of the glacier. ​ When a number of these merge - an outwash plain is formed.