3.1.4.4 Glacial Deposition Landforms

Question 1

2 ways debris transported by a glacier will eventually be deposited

Answer 1

• when it’s released by ice melting at snout

- when ice becomes overloaded with material

Question 2

What’s the most common till

Answer 2

Ablation till at snout

Question 3

What’s the name for subglacial debris till

Answer 3

Lodgement till

Question 4

What are the 4 landforms formed by glacial deposition

Answer 4

Drumlins
Erratics
Moraines
Till plains

Question 5

What’s a drumlin

Answer 5

Smooth egg-shaped hill up to 1.5km length + 50-60m in height

Question 6

What are the 2 ends of drumlins like

What do they show

Answer 6

Steeper ‘upstream’ end + gently sloping ‘downstream’ end

Show direction of ice advance

Question 7

Where are drumlins formed

Answer 7

Beneath glaciers

Question 8

What’s the most popular theory of how a drumlin forms

Answer 8

The glacier being overloaded by moraine compared to the energy it has, so struggled to cope with transporting the amount in the lower parts of the course and so deposits it

Question 9

What end of the drumlins means what

Answer 9

Blunt end - facing oncoming in

Tapered end - is the lee

Question 10

2 other theories of how drumlins form

Answer 10

Obstacles (resistant rock) in glaciers path encourage deposited material to be moulded into the drumlin shape

Glacial meltwater is responsible for eroding large hollows beneath ice and then infilling causing drumlins

Question 11

What are erratics

Answer 11

Rocks picked up + carried by ice, often for many kilometres and then deposited in areas of completely different lithology (rock type)

Question 12

What can you track by erratics

Answer 12

Track ice movements, by determining where rocks originated from

Question 13

What are moraines

Answer 13

Lines/series of mounds of material mainly running across glacial valleys

Question 14

What moraine is found at the snout

Answer 14

Terminal/end moraine

Question 15

Describe terminal moraine

Answer 15

Steep-sided
Can reach up to 50-60m high
Often moulded to the form of the snout

Question 16

When do terminal moraines form

Answer 16

When ice melts during snout standstill, when its reached its furthest point down a valley + material has been deposited

Question 17

When can recessional moraines be formed along the length of the valley

Answer 17

As the glacier retreats

Question 18

What are till plains

Answer 18

Wide areas of flat relief created by a till sheet (thick glacial till, sand + gravel)

Question 19

Where are rill plains often found

Answer 19

Behind a terminal moraine/towards former ice sheet margins

Question 20

Why are till plains usually poorly drained with bigs, lakes and slow moving meandering streams

Answer 20

As depth can vary and a lot of material tends to be compacted

Question 21

When are till plains formed

Answer 21

When ice melts leaving a layer of till behind

Question 22

What’s drift

Answer 22

All glacial deposits (subdivided into till + glacifluvial material)

Question 23

What’s till

Answer 23

Unsorted mixture of rocks,clay and sand mainly transported as supraglacial + englacial debris and then deposited

(all material deposited by glacier itself)

Question 24

What’s glacifluvial material

Answer 24

All material deposited by meltwater streams