OCR A Level GL - 10 OCR A Level GL 2.2b LAKE DISTRICT CASE STUDY Flashcards
The Lake District is a case study of …
An upland landscape associated with the action of valley glaciers
What are the 3 main groups of geology in the Lake District?
- Skiddaw slates 2. Borrowdale volcanics 3. Windermere series
What has the geology affected
The evolution (shaping) of the landscape
What are the oldest rocks in the Lake District?
Skiddaw group
How were the Skiddaw rocks formed?
black muds and sands settling on the sea bed
How long ago were the Skiddaw rocks formed?
500 million years ago
What has happened since the Skiddaw rocks were formed?
They have been raised and folded by tectonic forces
Where is the Skiddaw group of rock usually found?
Northern Lake District
What are the characteristics of the landscape in the Skiddaw
the mountains are smooth and streams occupy deep gorges
Where are Borrowdale volcanic rocks found?
Central Lake District
What are Borrowdale volcanic rocks composed of?
Consist of hard lava and ash from eruptions
How long ago were Borrowdale volcanic rocks formed?
450 million years ago
Which 2 highest mountains in the Lake District does Borrowdale volcanic rocks make up?
Helvellyn and Great Gable
What makes up the Windermere group of rocks?
Sedimentary mudstones, sandstones, siltstones and limestone
How long ago were the Windermere rocks formed?
420 million years ago
What has happened to Windermere group since they were formed?
They have been faulted and folded, pushed up and eroded down
Where are most of the Windermere group?
Southern Lake District
When was granite formed?
400 million years ago
When was carboniferous limestone formed in the Lake District?
500 million years ago
What has happened in the Lake District over the last 400,000 years?
There have been many glaciations where valley glacier and ice sheets submerged the landscape
What did these glaciations do to the landscape of the Lake District?
Glacial erosional and depositional landforms developed
Which geological epoch caused the landscape in the Lake District that we see now?
Pleistocene period (during last million years)
How many glaciations occurred during the Pleistocene period?
20 glaciations
Which glaciation took place between 12,800 and 11,500 years ago?
Loch Lomond Stadial
What erosional landform is situated in the Norfolk Valley?
Roche Mountonnee
What is the name of the Roche Moutonnee found in the Lake District?
Norfolk Valley
Which erosional landforms are situated on the west side of the Helvellyn Range?
Truncated spurs and hanging valleys - waterfall called Helvellyn Gill
Give a named example of an arete (erosional landform) in the Lake District?
Striding Edge in the Helvellyn Range
How long and high is the Helvellyn Range?
11km long and 600m high
Which glacial erosional landform can be found at 950m above sea level on Helvellyn Range?
A pyramidal peak
Why is the pyramidal peak on Helvellyn range as sharply eroded as some?
It lacks more than 2 corries on the western side of the mountain
What are the names of the two corries separated by Striding Edge?
Striding Edge arete separates Red Tarn Corrie and Nethermost Corrie
What is the name of the tarn formed in one of the corries below Helvellyn?
Red Tarn
Meltwater from Red Tarn glacier did what?
Meltwater flowed into the valley of Glenridding forming a valley glacier which then flowed into a U-shaped valley
What erosional feature is there at the bottom of the U-shaped valley made by the Red Tarn meltwater?
a ribbon lake called Ullswater
How were the drumlins in the Lake District formed?
Ice depositing layers of till and then moving back over the deposit to sculpt it into egg shaped hills
Where is a drumlin field in Lake District?
South of Kendal
What are the characteristics of the drumlins south of Kendal?
Lie on carboniferous rocks Range from 50-125m high
In which direction do the Kendal drumlins show ice movement?
North to South
When was the last glacial retreat?
11,000 years ago
What was left when these glaciers retreated 11,000 years ago?
Moraines in the valleys
What is a named example of a moraine deposited in the Lake District?
Lateral Moraine on the right bank of Langstrath valley, foot of Greenup Gill
Where are crescentic ridges of moraine found?
At the end of Blea Water Tarn in Mardale
What kind of moraines are they at the end of Blea Water Tarn in Mardale?
Recessional moraines - each one formed during a stationary period of the glacier on its retreat
Where is a small terminal moraine situated?
Southeast of Keswick, Naddle Valley
How big and long is the terminal moraine?
200-400m long and 10-15m high with a small lake situated behind it
What are erratics?
Boulders or rock transported in the ice, deposited when they ice has no more energy to carry it and do not match the rock type of their surroundings.
Which geologic group are most erratics in the Lake District from?
the Borrowdale volcanics group
Where are most erratics found in the Lake District?
they were transported 30km southeast and deposited on carboniferous limestone at Witherslate
How big can erratics be?
Some are 3m wide in diameter
