Fluvial glacial landforms

Question 1

Name 3 distinctive fluvial-glacial landforms

Answer 1

Kames
Eskers
Outwash plains

Question 2

What is a kame?

Answer 2

A hill or hummock composed of stratified sand and gravel laid down by glacial meltwater

Question 3

What are the two types of kame?

Answer 3

Delta kame

Kame terrace

Question 4

Describe the different ways delta kames are formed

Answer 4

1. En-glacial streams emerging at the snout of a glacier, losing energy at the base of the glacier and depositing its load
2. Supraglacial streams depositing material upon entering ice-marginal lakes and losing energy
3. Debris-filled crevasses collapsing during ice retreat

Question 5

What is a kame terrace?

Answer 5

A ridge of material running along the edge of the valley floor

Question 6

How are kame terraces formed?

Answer 6

Supra-glacial streams on the edge of a glacier pick up later moraine which is later deposited on the valley floor as the glacier retreat

Question 7

How do the supra-glacial streams, which create kame terraces, form?

Answer 7

They form due to the melting of ice in contact with the valley side as the result of friction and the heat-retaining properties of the valley-side slopes

Question 8

What is the difference between kame terraces and lateral moraines?

Answer 8

Similar but kame terraces contain fluvioglacial deposits that are more rounded and sorted

Question 9

Give an example of a kame terrace:

Answer 9

In the Kingsdale Valley of the Yorkshire Dales, a kame terrace extends for about 2km along the north side of the valley and is approx 2m high

Question 10

What is an esker?

Answer 10

A long sinuous ridge of stratified sand and gravel laid down by glacial meltwater

Question 11

Eskers: When is material deposited in subglacial meltwater channels?

Answer 11

As the supply of meltwater decreases at the end of the glacial period

Question 12

Eskers: When does deposition occur?

Answer 12

When the huge pressure inside the channel is released and meltwater emerged at the glacier snout

Question 13

Eskers: Why does the point of deposition move backwards?

Answer 13

Because the glacier snout retreats

Question 14

Eskers: What does it mean if an esker is beaded?

Answer 14

The ridge shows significant variation is height and width

Question 15

Give an example of an esker:

Answer 15

Trim esker near Dublin is 14.5km long and 4-15m high

Question 16

What is an outwash plain/sandur?

Answer 16

A flat expanse of sediment in the pro-glacial area

Question 17

How is an outwash plain formed?

Answer 17

As meltwater streams use energy in lowland areas, they deposit their load with the largest material deposited nearest the ice front and the smallest being deposited furthest away

Question 18

What are outwash plains typically drained by?

Answer 18

Beaded streams

Question 19

What are beaded streams?

Answer 19

River channels subdivided by numerous islets and channels

Question 20

What does braiding begin with?

Answer 20

Begins with a mid-channel bar which grows downstream

Question 21

How does a mid-channel bar grow and how does this cause braiding?

Answer 21

• Discharge decreases after a flood or period of snow melt causing coarsest particles to be deposited first
• Discharge continues to decrease so finer deposits added = increasing bar size
• Channel bars are then colonised by vegetation at times of low discharge
• River divides around the island and re-joins

Question 22

What are the characteristics of unvegetated bars? + why are they common in outwash areas?

Answer 22

They lack stability and often move, forming and re-forming

They are common in outwash areas due to seasonal fluctuations

Question 23

Give an example of a sandur:

Answer 23

South coast of Iceland is an extensive sandur fed by numerous meltwater streams = 5km

Question 24

Why is it often difficult to identify fluvio-glacial deposits?

Answer 24

Repeated advance and retreat modifies the appearance of landforms + subject to weathering, erosion and colonisation by vegetation in post-glacial times

Question 25

What happens to each of the three major fluvioglacial landforms as temperatures increase?

Answer 25

Outwash plains = greater accumulation as increased meltwater and exposed outwash material is colonised by lichens and mosses
Kames and eskers exposed in greater numbers and will become longer