9. Depositional Landforms

Question 1

what is glacial drift?

Answer 1

all sediment/debris transported under glacial conditions

Question 2

what is fluvioglacial sediment?

Answer 2

sediments deposited by meltwater streams

Question 3

what is till?

Answer 3

ablation till = debris dropped in-situ by retreating ice

lodgement till = material dropped subglacially e.g. around a nucleus of hard material

Question 4

is till sorted?

Answer 4

NO

glaciers transport all material at the same speed, regardless of size

this means all are deposited at the same rate also

Question 5

what sort of material do glaciers deposit?

Answer 5

angular rocks

Question 6

what are erratics?

Answer 6

any rocks that are made up of a different rock type than the bedrock

can be smaller than a pebble or larger than a boulder

Question 7

what is moraine?

Answer 7

ridges, mounds and hummocks formed at the margins of glaciers

Question 8

how does sediment reach glaciers? (and contribute to moraine)

Answer 8

plucking, abrasion and freeze-thaw weathering

Question 9

how does lateral moraine form?

Answer 9

at the sides of a glacier
lines of material are deposited

Question 10

how does medial moraine form?

Answer 10

in the middle of a glacier
after two glaciers meet (confluence), two lateral moraines join to form medial moraine

if the glacier melts, it leaves behind a long ridge of earth in the middle of the valley

Question 11

how does hummocky moraine form?

Answer 11

sediment carried by tiny streams is blocked and so slowly builds up underneath a glacier

if the glacier melts, the ground moraine beneath is exposed

Question 12

what is hummocky moraine?

Answer 12

rolling, strangely-shaped land covered in grass/vegetation

unlike other moraines, it has no sharp ridges

Question 13

what are terminal moraines also known as?

Answer 13

end moraine

Question 14

what are recessional terminal moraines?

Answer 14

markers of the extent of glacial advance in previous years which did not surpass the terminal moraine

Question 15

what do terminal moraines show?

Answer 15

change over time

any minerals present mean the glacier must have flowed though a region with this rock type/mineral

Question 16

how does terminal moraine form?

Answer 16

in a bulldozer effect, the glacier pushed material towards the toe

the terminal moraine marks the furthest this material has ever been pushed