Glacial Landscapes Flashcards
When was the last ice age and how thick was the ice?
22,000 years ago
3km
What is an interglacial period?
A period marked by the retreat of ice to higher altitude when temperatures are warmer for a longer period of time
What are milankovitch cycles?
Eccentricity - earth moving away/towards the sun (extreme 100,000 years)
Obliguity - degree of tilt towards the sun (every 41,000 years)
Procession - the wobble (every 23,000 years)
How do glaciers form?
- snow remains in the same area for years and slowly transforms into ice
- new layers of snow bury the previous ones
- compression forces the snow to recrystallise
- these grains grow larger and d the air pockets get smaller, so density increases
- this snow turns into firn/neve after roughly two winters
- this takes over 100 years after this
What is weathering?
Breakdown of rocks in situ
What is plucking?
Where the glacier moves over an area of rock, freezes and rips it when the glacier continues to move forward
What is abrasion?
Where the rocks at the bottom of the glacier act like sandpaper - can cause striations
What are striations?
Sharp grooves in the rocks
What are the three transport processes in glaciers?
Subgalcial
Englacial
Supraglacial
What is subgalcial material?
Material carried underneath the ice
What is englacial material?
Material transported inside the ice
What is supraglacial material?
Material carried on the top of the glacier
What is sediment transported by ice called?
Glacial till
What can glacial till form?
Moraines
What is bulldozing?
When a glacier moves forward it can pile up sediment in front of it to create a moraine
What is lodgement?
A type of till that is spread onto the valley floor beneath the ice
What is ablation till?
Till that is dropped as the ice melts
What is a recessional moraine?
A moraine that is formed as the glacier bulldozes and retreats of periods of time
What is a lateral moraine?
Sharp crested piles of till that are dropped as the moraine retreats
What is a terminal moraine?
Where the glacier bulldozes the till forward at the snout
What is a medial moraine?
Till building up between two glaciers in the middle
What is a corrie?
Bowl shaped hollows with steep back walls and ridges
What can sometimes be contained in a corrie?
A tarn
How is a corrie formed?
- snow accumulates in depressions
- this becomes glacial ice and begins to overfill
- plucking occurs as the ice moves downhill leaving the back wall steeper
- freeze thaw weathering happens causing scree to be formed
- the hollow deepens due to abrasion
- there is less erosion at the front
- a ricks slip is formed
- when all of the ice melts a tarn is formed
What are arêtes?
A narrow ridge formed where two corries meet back to back
What are pyramidal peaks?
Where three or more corries form a single peak where the arêtes meet
What is a glacial trough?
A U shaped valley formed by a glacier moving
What is a hanging valley?
When river tributaries suddenly flow through exists in a gap
What is a truncated spur?
A landform that occurs when a valley fills with a glacier
Why do ribbon lakes form?
Different rates of erosion occur so some parts of the valley floor have deepened
What is a ground moraine?
Moraine spread all over the ground formed when a glacier retreats up a valley
What a drumlins?
Egg shaped hills composed of mounds of till
How is a drumlin formed?
Material is deposited underneath the glacier as a ground moraine
This is sculpted by further ice movements
You can tell this by the shape of it
What are the two ends of drumlins called?
Blunted end
Tapered end
How are glacial erratics formed?
They fall off of a cliff due to freeze thaw weathering
It is then transported by supraglacial transport
Once the glacier begins to melt and retreat it is deposited
What is honister pass?
A slate mine which is now closed down
Only working slate mine in England
How much slate does the uk import?
20% of the worlds slate
What are examples of forestry in the Lake District?
Ennerdale water
Spruce trees are invasive and are taking over
Planting 1/2 million native trees
How many tourists does the Lake District get?
20 million a year
How many houses in the Lake District are lived in all year round?
2/28
What are examples of tourism in the Lake District?
Scaffel pike
Lake Windermere is uks largest lake
Hiking, cycling and nature watching
Shops, hotels, tourist attractions
What is farming like in the Lake District?
Widespread sheep grazing
Primarily hay or silage crops
Specialist farming (highland beef, cattle and deer)
What is forestry like in the Lake District?
Mostly involves conifer plantations
Fast growing trues suited to harsh climates
Used to proved wood for furniture
What is quarrying like in the Lake District?
13 acting quarries
Slate used for roofing
