what glacial landforms are there

Question 1

what are the seven erosional landforms

Answer 1

1. corries
2. aretes
3. pyramidal peaks
4. troughs
5. roche mountonnees
6. striations
7. ellipsodal basins

Question 2

what are the four types of depositional landforms

Answer 2

1. moraines
2. erratics
3. drumlins
4. till sheets

Question 3

describe the shape of a corrie in four points

Answer 3

• arm chair shaped
• high back wall
• over deepened basin
• often have a lip at the front

Question 4

give a specific example of a corrie and a distinctive characteristic of this

Answer 4

Walcott corrie antarctica has a 3km tall back wall

Question 5

describe in three stages explain the formation of a corrie

Answer 5

1. in the periglacial period snow will collect in a hillside hollow, nivation will occur deepening the hollow, eventually diagnesis occurs and this becomes glacier ice.
2. in the glacial period the ice will acquire a rotational movement under its own weight, causing the plucking of the back wall and making it increasingly steep, the thinner ice at the front has less rapid erosive power so a high lip is left.
3. in post glacial periods water may accumulate in the corrie causing a tarn lake.

Question 6

describe aretes in two points and an example

Answer 6

• a narrow steep sided ridge found between two corries
• they are often so steep that they are described as knife edged
• striding edge in the lake district is an example with steep slopes either side that are 200-300m tall

Question 7

describe a pyrimidal peak in one point and an example

Answer 7

• the product of three or more corries forming around a mountain or hill with retreated back walls
• the matterhorn pyrimidal peak in the swiss alps is over 1200m high

Question 8

describe the formation of glacial troughs

Answer 8

-when pre existing glaciers move down a valley due to the resultant force of gravity they erode the sides and floor of the valley causing it to widen, deepen and become straighter

Question 9

describe the shape of glacial troughs in three points

Answer 9

• although often described as U shaped, they rarely are.
• when compressing flow occurs the valley is over deepened to form rock basins and rock steps
• bands of weaker and stronger rock types will increase this effect

Question 10

how are roche mountonees formed

Answer 10

-as ice passes over projections of resistant rock on the valley floor of a glacial trough are there is localised pressure on the up valley side and melting occurs, resulting in this area being smoothed and streamlined by abrasion with striations. on the down valley side pressure decreases and meltwater re freezes reulting in plucking and steepening.

Question 11

what are striations

Answer 11

scratches and grooves made by the debris embedded in the bottom of a glacier

Question 12

describe the size of roche mountonees using a specific example

Answer 12

in the consiton area of the lake district they are typically 1-5m high and 10-20m long.

Question 13

why are roche mountonees so important today

Answer 13

they can indicate the direction that a glacier was moving in.

Question 14

what are the three types of moraine

Answer 14

lateral, terminal, recessional

Question 15

what is a lateral moraine

Answer 15

debris deposited along the side of a glacier, comprising of both rockfall debris from above and debris ground up by ice marginal processes below.

Question 16

what is a terminal moraine

Answer 16

a prominent ridge of glacial debris formed when a glacier reached its maximum limit during a sustained advance

Question 17

what is a recessional moraine

Answer 17

a series of ridges running transversely across glacial troughs, representing a stationary phase in an otherwise general retreat

Question 18

what is an erratic

Answer 18

an individual piece of rock that can vary in size from a small pebble to a boulder that is distinctive because its geology is different from that in the areas that it is found. It has been eroded or added to the supraglacial debris of a glacier by weathering or rockfall in one area of geology and transported to another area of geology where it is deposited by a glacier.

Question 19

what is a specific example of an erratic

Answer 19

the erratic blocks of silurian shale deposited on carboniferous limestone at norber in the yorkshire dales

Question 20

what is a drumlin

Answer 20

a mound of glacial debris that has been streamlined into a prominent elongated hill. the stoos end is the higher, blunt side whilst the lee slope is gently tapering.

Question 21

give two theories for the formation of drumlins

Answer 21

their formation is not fully understood, two theories are:

• the reshaping of previously deposited material during a subsequent re-advance
• thinning of ice as it spread out over a lowland area, reducing its ability to carry and deposit debris