Glacial Landscapes Flashcards
(67 cards)
What are the three types of glacial landform?
- Depositional
- Erosional
- Fluvioglacial
What are the erosional landforms?
Roche Moutonnée
U-shaped valley
Truncated Spur
Hanging Valley
Crag and Tail
Corrie
Arête
Ribbon Lake
Tarn
Pyramidal peak
How can we categorise erosional landforms?
Macro
Meso
Micro
What are the macro erosional landforms?
Corrie
Arête
Pyramidal Peak
U-shaped valley
Ribbon lake
Hanging valley
Truncated spurs
What are the meso erosional landforms?
Roche Moutonnée
Crag and Tail
What are the micro erosional landforms?
Striations
What are the depositional landforms?
Moraines
Drumlins
Erratics
Till Plains
What is moraine?
The accumulation of unsorted debris (till) deposited directly by a glacier as it advances and retreats
What is till?
Unstratified (no layers) and unsorted sediment containing a mix of rock particles (clay, sand, gravel, boulders) deposited by a glacier
What are the six different types of moraine?
- Lateral
- Medial
- Terminal
- Ground
- Recessional
- Push
Where are the different types of moraine found?
- LATERAL
- sides - MEDIAL
- middle of two merging - TERMINAL
- end - GROUND
- underneath - RECESSIONAL/PUSH
- behind terminal moraine, marking stages of glacial retreat and/or readvancement
How is lateral moraine formed?
Debris falling from the cliffs at the side of the glacier due to freeze-thaw action gets trapped at the edges and transported as the glacier moves
How is medial moraine formed?
When the lateral moraines of two converging glaciers join together
How is terminal moraine formed?
When the debris pushed at the glaciers snout is deposited as a ridge when the glacier reaches its maximum extent and begins to retreat
How is ground moraine formed?
As the glacier moves it deposits a thin irregular layer of till at its base
How is recessional moraine formed?
When a retreating glacier temporarily stabilises, depositing a ridge of debris before continuing to melt back
How is push moraine formed?
If the glacier advances again after retreating then ridges of sediment previously deposited get shoved up into little hills
What does recessional/push moraine look like?
A series of ridges behind the terminal moraine, showing pauses in the glaciers retreat.
Can show folding/faulting/tilting due to the force of the glacier moving forward
Often curved and perpendicular to the direction of the glaciers advancement
What are drumlins?
Give an example
Elongated, egg-shaped hills made of till formed when a glacier moving over an obstruction deposits and shapes till over the to of it
e.g. The Drumlin Field beneath Cam Fell, Yorkshire Dales
What are eratics?
Give an example
large, random rocks transported by glaciers hundreds, sometimes thousands of km from where they originate. They do not fit with the size or type of rocks in the area in where they are deposited
e.g. The Great Stone of Fourstones, moors of Tatham Fell, England
What is a glacial outwash plain?
Give an example
Where till is carried and deposited by meltwater streams in layers further down the valley from the glacier snout
e.g. Lake Clarke National Monument, Alaska
What is another name for a glacial outwash plain?
Sandur
What is outwash?
Sediment that has been transported away from a glacier by meltwater
Why do you get layering in the outwash plain?
changing competence over time:
- bigger stuff is deposited in summer due to more meltwater = large sediment, high competence
- smaller stuff is deposited in winter due to less meltwater = small sediment, low competence