Glaciation Pack I

Question 1

What does moraine refer to?

Answer 1

Distinct ridges or mounds of debris that are laid down directly by a glacier or pushed up by it
- Ice contact
- Unsorted

Question 2

Where are the 5 types of moraine found?

Answer 2

Lateral - along the glacier/valley side
Medial - in the middle of the glacier surface (supraglacial)/middle of the valley floor
Terminal - at the glacier terminus (furthest point the glacier reached)
Recessional - behind a terminal moraine
Push - at the snout of active glaciers

Question 3

What leads to the 5 types of moraine?

Answer 3

Lateral:
- Consists of debris that falls or slumps from the valley wall or flows directly from the glacier surface
- Exposed rock on the valley side is weather and fragments fall
- Carried along the glacier and deposited when the ice melts
- Parallel to ice flow

Medial:
- Two valley glaciers converge
- Form when lateral moraines meet and combine at the confluence
- Parallel to ice flow

Terminal:
- Marks the maximum limit of glacier advance
- Advancing ice carries moraine forward and deposits it at the point of maximum advance when it then retreats
- Transverse to ice flow

Recessional:
- Form during short-lived phases of glacier advance or standstill that interrupt a general pattern of glacier retreat
- Transverse to ice flow

Push:
- Rock and sediment debris at the ice margin is moulded into ridges by the bulldozing of material by an advancing glacier
- Transverse to ice flow

Question 4

What is a ground moraine?

Answer 4

• An uneven blanket of till deposited in the low-relief areas between more prominent moraine ridges
• Forms at glacier sole due to the deformation and eventual deposition of the debris under the glacier

Question 5

What is a kame and how can a kame be described?

Answer 5

Rounded mound or conical hill of fluvioglacial deposits that were once in contact with the ice

Question 6

What is an example of a kame?

Answer 6

Fonthill Kame, Niagara, Canada

Question 7

What are the characteristics of a kame?

Answer 7

• Ice contact
• Fluvioglacial deposition
• Under or next to a glacier
• Near the end of the former glacier as it began to retreat
• Stratified

Question 8

What causes kames to form?

Answer 8

• Deposition of material in ice (hollows such as crevasses or moulins)
• Gradually gets lower as the ice melts

Question 9

What is kame terrace and how can a kame terrace be described?

Answer 9

Relatively continuous bench-like features along the valley side

Question 10

What is an example of a kame terrace?

Answer 10

Loch Etive, Scotland

Question 11

What are the characteristics of a kame terrace?

Answer 11

• Parallel to the valley
• More rounded
• May be sorted

Question 12

What causes a kame terrace to form?

Answer 12

• A gap or lake between the valley side and the ice margin is filled with fluvioglacial deposits
• Meltwater runs between the glacier and the side wall

Question 13

What is an esker and how can an esker be described?

Answer 13

A long, sinous ridge of sands and gravel deposited by meltwater flowing through subglacial or englacial tunnels

Question 14

What is an example of an esker?

Answer 14

Thelon Esker, Canada (800km)
Munro Esker, Canada (400km)

Question 15

What are the characteristics of an esker?

Answer 15

• Ice contact
• Fluvioglacial deposition under the glacier
• Parallel to former ice flow
• Usually at margins of warm-based glaciers
• Horizontally sorted
• Rounded deposits

Question 16

What causes eskers to form?

Answer 16

• Meltwater flows in or under glaciers in tunnels
• The meltwater carries material
• When velocity falls, sediment will be laid down on the floor of the tunnel
• If a tunnel becomes blocked by sediment or ice, water and sediment is ‘ponded’ behind the blockage
• A tunnel on the base of the ice will preserve sediments
• A tunnel lying within the ice will disturb sediments as ice melts and sediments drops to the valley floor

Question 17

What is a sandur and how can a sandur be described?

Answer 17

A flat expanse of rounded, sorted and stratified sands and gravels and is a fluvioglacial landform created by deposition by meltwater

Question 18

What is an example of a sandur?

Answer 18

Porsmork Valley, South Iceland

Question 19

What are the characteristics of a sandur?

Answer 19

• Proglacial
• Depositional
• No ice contact
• Stratified

Question 20

What causes sandurs to form?

Answer 20

• When meltwater emerges from the snout, it loses energy as it is no longer flowing under hydrostatic pressure
• The material it is carrying is deposited, largest first and finest material carried furthest
• Sediment is laid down in layers during annual flood events and during periods of higher discharge (in summer)
• Highly variable discharge causes rivers to split in smaller streams to travel around areas of deposition, known as braided streams

Question 21

What is a varve and how can a varve be described?

Answer 21

A pair of thin layers of contrasting colour, texture and sediment size

Question 22

What is an example of a varve?

Question 23

What are the characteristics of a varve?

Answer 23

• Proglacial
• Depositional
• No ice contact
• Stratified

Question 24

What causes varves to form?

Answer 24

• Proglacial lakes develop in front on glaciers in depressions in the ground which meltwater flows into
• Seasonal changes in deposition happen due to the varying amounts of meltwater
• In the melting season, there is a lot of meltwater and lots of material is transported
• A lot of heavier material will be being carried so this is deposited in a thicker layer of larger material
• In the non-melting season, there is very little meltwater so very little material is carried
• Fine sediment particles (e.g. clay) will be laid down
• Winter deposition is thin clay beds, whereas summer deposition is thicker sand and gravel beds
• Build up year after year

Question 25

What are kettle holes and how can they be described?

Answer 25

Small round depressions found in zones where dead ice was left on an outwash plain by a retreating glacier

Question 26

What is an example of a kettle hole?

Answer 26

Ellesmere, North Shropshire

Question 27

What are the characteristics of a kettle hole?

Answer 27

• Proglacial
• Depositional
• No ice contact

Question 28

What causes kettle holes?

Answer 28

• Dead ice was left on an outwash plain by a retreating glacier
• As meltwater streams came out of the ice, they buried the blocks of dead ice under deposits of sorted and stratified sediments
• The ice melted and a depression was left

Question 29

What causes kettle lakes?

Answer 29

• When a kettle hole fills up with rainwater