❄️ Physical: Glaciated Landforms Flashcards
What caused the last ice age?
Every 100 years the Earth’s orbit becomes slightly elongated, making summers shorter and cooler and winters snow fails to melt. Temperatures dropped and ice grew
What is a glacier?
A slow moving mass of ice downhill under the influence of gravity.
How do glaciers form?
- Glaciers form when snow remains in the same area year-round, slowly transforming into ice
- Each year, new layers of snow bury and compress the previous layers
- This compression forces the snow to re-crystallise, forming grains similar to sugar
- Gradually the grains grow larger and the air pockets between them get smaller, causing the snow to slowly compact and increase in density
- After about two winters, the snow turns into firn - a middle state between snow and glacier ice
- For most glaciers, this process takes more than 100 years
What is weathering?
The breakdown of rocks in-situ by the action of rain water, extreme temperatures and biological activity.
Explain the process of freeze-thaw weathering.
- Rain water falls into a crack in a rock
- The water freezes and causes the rock to expand
- The rock then breaks into tiny pieces
What is plucking?
Where a glacier moves over an area of rock and due to friction, the glacier melts and water seeps into cracks around the rocks below. The water refreezes and the rock effectively becomes part of the glacier and is ripped.
What is abrasion?
Where rocks at the bottom of the glacier act like sandpaper - grinding over the bedrock. This can polish the rocks or create sharp grooves called striations.
What are the 3 different ways glaciers can transport debris (till)?
- Supraglacial material: On top
- Englacial material: Inside
- Subglacial material: Under
What is bulldozing?
When a glacier moves forward it can act like a giant earthmover, bulldozing piles of rock debris in front of it to create a high ridge called moraine.
What is outwash?
The sediment meltwater rivers carry.
Why is outwash more rounded?
Attrition in the river which erodes their sharp edges.
What is a landform?
A natural feature on the Earth’s surface caused by geographical processes.
What are corries?
Bowl shaped hollows with a steep back wall and ridges, forming an armchair shape around a hollow. Sometimes containing a small round lake called a tarn.
How is a corrie formed?
- Snow accumulates in depressions high up, predominantly on north facing slopes
- Over time the snow becomes glacial ice and there’s more ice than the depression can hold and some starts to flow to other levels
- Freeze-thaw weathering occurs at the top of the slope producing scree which becomes incorporated into the glacier
- The hollow deepens where the ice is thickest due to abrasion. Rock debris acts as tools to wear away the bottom of the hollow
- Ice becomes frozen to the back of the hollow and plucking occurs as blocks of rock are pulled away as the ice moves downhill. This makes the back wall steeper and these rock fragments become incorporated into the glacier.
- There is less erosion at the front where the glacier leaves the corrie hollow to flow down the valley; a rock lip forms here as a result of less powerful erosion
- When all the ice has melted a tarn forms
What are aretes?
A narrow ridge formed when two corries meet back to back.
What are pyramidal peaks?
When three or more corries form a single peak where the aretes meet.
What is an example of an arete?
Crib Goch in Wales
How are ribbon lakes formed?
- As a glacier flows it travels over hard and soft rock
- Softer rock is less resistant to erosion, so the glacier will carve a deeper trough over it
- When the glacier has melted, water collects in these deeper areas, creating a ribbon lake
What are the characteristics of ribbon lakes?
- Long
- Thin
- They’re in U shaped valleys/glacial troughs
What is an erratic?
A large boulder transported and deposited by glaciers in areas with a different rock type.
What are truncated spurs?
Past interlocking spur edges of past river action that have been cut-off forming cliff-like edges on the valley side.
How are truncated spurs formed?
- The front of a glacier acts as a bulldozer, removing soil + plucking rocks from interlocking spurs
- This process turns interlocking spurs into truncated spurs
Where are truncated spurs found?
Between hanging valleys
What is a glacial trough?
Steep-sided valleys with a flat floor
How are glacial troughs formed?
- As a glacier moves down a valley it plucks rocks from beneath it
- These rocks abrade the valley floor, eroding it further which deepens and widens the valley
- At the front, the glacier acts as a bulldozer, removing soil + plucking rocks from interlocking spurs
How are hanging valleys formed?
- Tributary glaciers are smaller and therefore have less mass
- In result, they erode the ground less and the main valley is deeper + wider
- They can sometimes form waterfalls when the glacier melts and rivers return
What are the 4 types of moraine?
- Terminal Moraine
- Lateral Moraine
- Medial Moraine
- Ground Moraine
What is terminal moraine?
The massive ridge of deposited material that gets bulldozed to the snout of the glacier.
What is lateral moraine?
The material around the edge of the glacier which comes from weathering from the sides of the valley.
What is medial moraine?
Ridge of deposited material in the middle where two glaciers meet.
What is ground moraine?
Material that gets lodged and deposited underneath the glacier.
What are drumlins?
Elongated, egg shaped hills made of glacial till.
How are drumlins formed?
- When the glacier meets an obstruction, material is deposited as ground moraine
- The moraine is then shaped by the moving ice
- As the material is deposited, it builds up to have a round, blunt and steep front (stoss)
- The glacier drags the material along and down, creating a lee slope
What do drumlins show?
The direction of glacier flow
What activity takes place on glacial moraine?
Farming in lowland areas
What are 2 human characteristics in the lake district?
- 15% of homes are holiday homes
- Provides 18,000 jobs
What are 4 main economic activities in the Lake District?
- Tourism
- Farming
- Forestry
- Quarrying
What is tourism like in the Lake District?
Spectacular landscapes and scenery attract people to the hiking, cycling, climbing, nature watching and some water sports
What is farming like in the Lake District?
- Difficult due to steep relief, thin soils and waterlogged soils in upland areas
- Temperatures are lower in higher altitudes and landscape creates shade in some areas
- Extensive pastoral farming occurs
- Heavy rainfall and strong winds
- Extensive sheep grazing is widespread
What is extensive pastoral farming?
A type of agriculture that involves raising livestock on large farms with relatively low labour and resource inputs.
What is forestry like in the Lake District?
- Pine trees grow quickly and can be harvested often which is a good source of money
- There are 2 million hectares of coniferous in the UK
- The wood is used in construction, furniture and fuel e.g Grizedale in the Lake District
- Some of the forests are used for tourist activities like walking and cycling
What is quarrying?
The process of extracting natural resources like sand, gravel, rock, and other minerals from the earth to be used in construction or other projects.
What is quarrying like in the Lake District?
- Mining still takes place to make roof tiles, work surfaces and pavements e.g the Honister Slate Mine
- Some are used as tourist attractions once closed to mining e.g HSM
What opportunities does the Lake District provide?
- Wood Harvesting
- Tourist Attractions
- Retail Jobs
- Mining
- Farming - sheep grazing
What are some conflicts of land use in the Lake District?
- Cyclists eroding the upland areas and paths
- Tourists destroying farm land with their pets
- Locals don’t want tourists harming and destroying their landscapes
What is a honeypot site?
A place of natural or human interest that attracts people in large numbers.
What features make Lake Windermere a honeypot site?
- Art galleries
- Water sports
- Bike hires
- Lake side aquarium
- World of Beatrix Potter attraction
- Shopping + Eating
- Brockhole activities centre (“Tree Top Trek”)
- Fishing
- Holehird Gardens
- Wray Castle
- Ferry across Windermere
What are the impacts of tourism at The Lake District?
- Litter
- Air Pollution
- Footpath Erosion
- Traffic Congestion
- Limited Property Supply
What are some strategies to manage the impacts of tourism in the Lake District?
- ## Plans to enable 50% of people to come by rail + integrated onward travel to lower traffic
