glacio fluvial landforms Flashcards
Moulin
A roughly circular vertical well like shaft formed where a surface melt stream exploits a weaknes in the ice
How is a moulin formed?
- a supraglacial stream makes its way down through the glacier to the base - occurs due to melting ffrom temp increase
*
surface ater makes it way down to the base
What is a Kame ?
Low mounds or short irregular ridges composed of stratidied sand and gravel
How are kames formed?
- deposited by a subglacial stream at the margin of a melted glacier
- or by supraglacial deposit on surface or at margin of stagnant ice
- Shape/size dependent on where snow is accumulated
What is a Kame terrace?
Ridges of material that run along the edge of the valley floor as the glacier retreats.
Are found where meltwater runs between the glacier and the sidewall.
How are kame terraces formed?
- material is deposited when the flow is reduced
- supraglacial streams on the edge pick up lateral moraines - are deposited during retreat
streams form due to melting ice due to friction with valley sides
What is a Kame delta?
Roundeed mounfs of fluvio glacial deposits found near the end of the glacier as it is abt to retreat
How are Kame deltas formed?
- found near the end of the former glacier as it began to retreat
- meltwater held back by terminal moraine
- led to formation of lakes and material was deposited where the meltwater left the glaciers to flow into lakes
What is an Esker?
A long narrow winding ridge composed of stratidied sand and gravel
How is an Esker formed?
- material deposited in subglacial or englacial tunnels
- deposited as the supply of meltwater decreases at the end of a glacial period
- As the glacier retreats sediments left behind as a rodge
How are kettle holes formed?
- glacier retreats the block of ice is stranded
- ice gets surrounded by meltwater deposits and outwash
- as temp increases the ice block melts leaving **impression in ground
- ice occupies this **
What is an outwash plain ?
A flat spread of rounded, sorted and stratified debris.
How is an outwash plain formed?
- Formed in front of a glacier and are where material is deposited over a wide area carried out from glacier by meltwater
- drained by braided channel streams
- the larger the material deposited first as velocity falls smaller further away - naturally sorts the material
What is a braided stream?
A relatively shallow stream with many branches that commonly recombine and migrate across a valley floor .
What is a varve?
Is a distinct layer of silt lying on top of a layer of side deposited annually in lakes found near to glacial margins.
