Unit 7 Flashcards
(16 cards)
What are the three key themes of this unit, how do they relate to glaciation?
- Rapid
- Seasonal
- Long term (thousands of years)
how glacial landforms change over different timescales
What is an example of a glacial landform that experiences rapid change?
Scree Slopes
What is the case study for glacial landforms that experience rapid change?
- Nant Ffrancon Valley in Snowdonia
What is an example of an area where there was a mass landslide, due to scree slope formation?
April 1991, around 15 million m3 of rock slid down near the town of Randa in the Matter Valley, Switzerland
What was the total rock fall, how many meters down did it fall, in Randa, Matter Valley Switzerland?
33 million m3 of rock fell 600m to the valley floor
What were the impacts of the Randa rockslide, Switzerland?
33 buildings the rock fall blocked a 1.3km long stretch of the Vispa River
How and why fluvioglacial streams vary both daily and seasonally?
- discharge can vary wildly overtime, in summer discharge will be high as meltwater arrives from many melt water streams all over the glacier
- in winter. melt water discharge may even stop, as temperatures may never rise above PMP
What is an example of a landform that experiences seasonal changes?
Kettle hole lakes and proglacial lakes with varves
What are the three glacial landscapes that experience long term change?
- Alluvial fans (transportation and deposition by water)
- Misfit stream erosion by water
- Infilling of lakes (transportation and deposition of water)
What are alluvial fans?
are deposits of stream load at the base of the steep slope
they can form when fast flowing streams, running down the sides of the glacial trough, reach the valley floor
Where is there an example of an alluvial fan?
Beneath Cwm Coch in Nant Ffrancon Valley in Snowdonia
How do Alluvial fans form?
- streams flow down from mountain areas they possess a lot of energy, due to steep gradient allowing them to carry large amounts of sediment
- as they emerge at a low altitude velocity is reduced, depositing material
How are ribbon lakes infilled?
- sediment transported by the many streams flowing through glacial landscapes can gradually infill lakes
- occur similar to alluvial fans, as the velocity of the water is decreased
What is an example of infilled ribbon lake?
below Llyn Ogwen in Snowdonia
What is a misfit stream?
the running water that drains the post glacial landscape will converge at the base of a glacial trough to create a misfit stream
What is an example of a misfit stream?
Afon Ogwem flowing through Nant Ffrancon Valley
