Emergent landforms Flashcards
When do emergent landforms form?
When sea level falls, they were shaped by wave processes when sea levels were higher.
What are raised beaches?
Former shore platforms (at higher levels than present sea level) at base of relic cliffs
What are abandoned cliffs?
Found inland behind the present emergent coastline.
What are marine terraces?
Larger than raised beaches but also formed by previous marine erosion. Do not definitely have cliffs above them.
Facts about the Isle of Portland, Dorset (Raised beach/abandoned cliff):
Has a RB 15m above sea level, formed in Tyrrhenian period (erosion rates of 1m/yr!), limestone eroded by hydraulic action/exploitation of bedding plane weakness. The abandoned cliff, has limestone debris, a degraded cliff face (frost weathering led to rockfall). A result of permafrost freezing/thawing in Pleistocene period. Post glacial warmer period, more chemical weathering (carbonation)
After emergence what modification can occur?
Only affected by weathering and mass movement. But if temps increase rapidly and sea level rises again, these landforms might be at the coastline again and face wave processes.
How are climate change and sea level rise connected?
Increased meal global temp means land ice melts, volume of ocean store increases, sea level rises. A 1C rise in mean global temp leads to a 2m sea level rise.
What are eustatic changes?
Changes to global volume of water in the ocean (quantity in store and density).
What are isostatic changes?
Sea level changes are relative to land level changes.
What happens if global temperatures decrease?
More precipitation is snow, which turns to ice (stored as a solid on land), reducing the volume in ocean store and the sea level will fall. 1C fall leads to fall of approx. 2m.
