Glaciation (Lithosphere) Flashcards
- What is ‘plucking’?
- PLUCKING:
➞ where ice freezes on to bedrock 🧊
↳ pulling away any loose rocks 🪨
➜ from the back wall/valley sides.
- What is ‘abrasion’?
- ABRASION
➞ where angular rock
↳ embedded in the ice 🧊
➜ grinds the rock below as the glacier moves 🪨
- What is ‘frost shatter’?
- FROST SHATTER
➞ where water in cracks in the rock freeze, expand and contract ❄️
➜ weakening the rock until fragments break off
(this can create piles of broken rock called SCREE)
- What is the formation of a ‘corrie’?
🟢 BEGINNING:
1.) Snow ❄️
➞ accumulates in a north-facing hollow
↳ where more snow falls than melts in summer ☀️
2.) Accumulated snow
➞ compresses into NEVE
↳ and eventually on to form glacial ice 🧊
3.) Resulting glacier
➞ moves downhill due to gravity.
🟠 MIDDLE (PROCESSESS):
4.) Rotational sliding 🔃
➞ over deepens the hollow
5.) Bergshrund crevasse
➞ opens up at the back of the hollow, allowing in melt water and rock fragments to reach the base of the glacier
↳ increasing erosive power ⚡
6.) Erosion occurs through:
1. Plucking
➞ (where glacial ice freezes onto bedrock,
↳ pulling away any loose rocks away from the backwall 🪨)
-
Abrasion
➞ (occurs when angular rocks embedded in the ice
↳ grinds the hollow as the glacier moves) -
Frost shatter
➞ (is where water enters cracks in the rock, freezes, expands and contracts
↳ weakening the rock until fragments break off)
🔵 ENDING (FINAL PROCESSES):
9.) Friction causes glacier to slow down at edge of the corrie, causing a rock lip to form 👄
➜ due to less erosion ➖⚡
(traps rain water, forming a tarn)
10.) (e.g. Brown Cove)
- What is the formation of an ‘arete’?
🟢 BEGINNING:
1.) Snow ❄️
➞ accumulates in a north-facing hollow
↳ where more snow falls than melts in summer ☀️
2.) Accumulated snow
➞ compresses into NEVE
↳ and eventually on to form glacial ice 🧊
3.) Resulting glacier
➞ moves downhill due to gravity.
🟠 MIDDLE (PROCESSES):
4.) An arete is formed when the backwalls of 2 corries
↳ are eroded back-to-back.
5.) Rotational sliding 🔃
➞ over-deepens the hollow.
6.) Erosion occurs through:
1. Plucking
➞ (where glacial ice freezes onto bedrock,
↳ pulling away any loose rocks away from the backwall 🪨)
-
Abrasion
➞ (occurs when angular rocks embedded in the ice
↳ grinds the hollow as the glacier moves) -
Frost shatter
➞ (is where water enters cracks in the rock, freezes, expands and contracts
↳ weakening the rock until fragments break off)
🔵 ENDING (FINAL PROCESSES):
7.) The arete can become more pronounced due to continued frost-shattering ❄️
↳ which can also lead to the formation of scree slopes.
8.) (e.g. Striding Edge)
- What is the formation of a ‘pyramidal peak’?
🟢 BEGINNING:
1.) Snow ❄️
➞ accumulates in a north-facing hollow
↳ where more snow falls than melts in summer ☀️
2.) Accumulated snow
➞ compresses into NEVE
↳ and eventually on to form glacial ice 🧊
3.) Resulting glacier
➞ moves downhill due to gravity.
🟠 MIDDLE (PROCESSES):
4.) A pyramidal peak is formed when the back walls of 3 corries
➜ eroded back-to-back
5.) Rotational sliding 🔃
➞ over deepens the hollow.
6.) Erosion occurs through:
1. Plucking
➞ (where glacial ice freezes onto bedrock,
↳ pulling away any loose rocks away from the backwall 🪨)
-
Abrasion
➞ (occurs when angular rocks embedded in the ice
↳ grinds the hollow as the glacier moves) -
Frost shatter
➞ (is where water enters cracks in the rock, freezes, expands and contracts
↳ weakening the rock until fragments break off)
🔵 ENDING (FINAL PROCESSES):
7.) Pyramidal peak can become more pronounced due to continued frost shattering ❄️
➜ which can also lead to the formation of scree slopes.
8.) (e.g. Hellvelyn)
- What is the formation of a ‘u-shaped valley’?
🟢 BEGINNING:
1.) Snow ❄️
➞ accumulates in a north-facing hollow
↳ where more snow falls than melts in summer ☀️
2.) Accumulated snow
➞ compresses into NEVE
↳ and eventually on to form glacial ice 🧊
3.) Gravity
➞ causes the glaciers to flow down-hill ↘️
↳ following the existing v-shaped valley 🏞️
🟠 MIDDLE (PROCESSES):
4.) Erosion occurs through:
1. Plucking
➞ (where glacial ice freezes onto bedrock,
↳ pulling away any loose rocks away from the backwall 🪨)
-
Abrasion
➞ (occurs when angular rocks embedded in the ice
↳ grinds the hollow as the glacier moves) -
Frost shatter
➞ (is where water enters cracks in the rock, freezes, expands and contracts
↳ weakening the rock until fragments break off)
🔵 ENDING (FINAL PROCESSES):
5.) * Former interlocking spurs are cut off by the glacier as it flows down hill
↳ to form TRUNCATED SPURS & STEEP VALLEY SIDES
6.) The width & shape of the resulting glacial valley will depend on:
- nature of rock type 🧊
- the intensity & weight of the glacier ⚖️
- and its erosion ⚡
7.) A misfit stream
➞ can be found where the original river no longer fits the valley floor 🌊
8) (e.g. Grisdale Valley)
- What is the formation of a ‘hanging valley’?
🟢 BEGINNING:
1.) Snow ❄️
➞ accumulates in a north-facing hollow
↳ where more snow falls than melts in summer ☀️
2.) Accumulated snow
➞ compresses into NEVE
↳ and eventually on to form glacial ice 🧊
3.) Gravity
➞ causes the glaciers to flow down-hill ↘️
↳ following the existing v-shaped valley 🏞️
🟠 MIDDLE (PROCESSES):
4.) Erosion occurs through:
1. Plucking
➞ (where glacial ice freezes onto bedrock,
↳ pulling away any loose rocks away from the backwall 🪨)
-
Abrasion
➞ (occurs when angular rocks embedded in the ice
↳ grinds the hollow as the glacier moves) -
Frost shatter
➞ (is where water enters cracks in the rock, freezes, expands and contracts
↳ weakening the rock until fragments break off)
🔵 ENDING (FINAL PROCESSES):
5.) Former interlocking spurs are cut off by the glacier
↳ as it flows down hill to form
➜ TRUNCATED SPURS & STEEP VALLEY SIDES
6.) A ‘hanging valley’ is formed when a smaller tributary glacier erodes a valley
↳ but is left above the main valley
(has less erosive power ➖⚡)
7.) (e.g. Base Brown)
- What is the formation of a ‘ribbon lake’?
🟢 BEGINNING:
1.) Snow ❄️
➞ accumulates in a north-facing hollow
↳ where more snow falls than melts in summer ☀️
2.) Accumulated snow
➞ compresses into NEVE
↳ and eventually on to form glacial ice 🧊
3.) Gravity
➞ causes the glaciers to flow down-hill ↘️
↳ following the existing v-shaped valley 🏞️
🟠 MIDDLE (PROCESSES):
4.) Erosion occurs through:
1. Plucking
➞ (where glacial ice freezes onto bedrock,
↳ pulling away any loose rocks away from the backwall 🪨)
-
Abrasion
➞ (occurs when angular rocks embedded in the ice
↳ grinds the hollow as the glacier moves) -
Frost shatter
➞ (is where water enters cracks in the rock, freezes, expands and contracts
↳ weakening the rock until fragments break off)
🔵 ENDING (FINAL PROCESSES):
5.) Ribbon lakes can be formed if a terminal moraine creates a dam.
6.) Ribbon lakes are formed if softer bedrock is eroded more deeply than the surrounding area ⚡
7.) (e.g. Lake Windermere)
- What is the formation of a ‘terminal moraine’?
- Terminal moraine is a ridge across a valley made up of glacial deposits
➞ which is unsorted. - As the glacier moves downhill
➞ it acts like a bulldozer 🏗️
↳ pushing sediment at the front of its SNOUT 🐽 - On reaching lower altitudes, the temperature rises and the glacier melts
➞ and as a result, loses powers and deposits materials - Terminal moraine marks the furthest point the glacier reaches once the ice has retreated
➞ and can form a moraine dammed lake 🏞️
(creating a ribbon lake as water is unable to drain)
- What is the formation of a ‘drumlin’?
- Drumlins are elongated hills of unsorted materials
↳ deposited by the glacier - Glacier becomes overloaded with sediment and deposits it
↳ with the material then being streamlined (re-eroded) as the glacier moves over it. - Further, there can be an obstacle on the ground which may act as a trigger and material is deposited around it.
-
STOSS side is steeper
↳ as it is eroded by:
* Plucking
➜ (where ice freezes onto bedrock, pulling loose rocks away) -
LEE side is gentler
↳ as it is eroded by:
* Abrasion
➜ (where rock embedded in the glacier grinds the rock below) - Usually, it is found in groups called SWARMS 🐝
- What is the formation of an ‘esker’?
- The stones found in eskers are more rounded then other glacial deposits
➞ as the action of flowing water rounded the edges by erosion 🪨 - The deposits are SORTED by size,
➞ as the flowing water deposited the heaviest material first as it lost energy 🌊 - On reaching lower altitudes/or when temperature rise,
➞ the glacier begins to melt and sub-glacial streams deposited material in the tunnels under the glacier 🌡️ - Eskers are meandering ridges in the valley floor formed by melt water streams under the glacier.
➞ They contain meltwater sands and gravel ⌛
