Emergent Landforms Flashcards
Physical factors which influence global temperatures
Variations in the Earth’s orbit every 400 000 years
Changes in the composition of the atmosphere due to major eruptions which reduce incident solar eruption
Variations in the amount of energy produced by the sun
Impact of falling temperatures on precipitation
More precipitation in the form of snow which becomes ice that is stored on land rather being returned to ocean store as a liquid
Reduction in volume of water in the ocean store
Impact of falling temperatures on water molecules
As temp falls, water molecules contract leading to increased desnity and reduced volume in oceans.
1 degree drop in temp= 2m fall in sea level
When was the Tyrrhenian interglacial and what was the temp/ sea level during this period?
It was 130 000 years ago.
Global temperatures were 3 degrees higher than present and sea level was 20m higher than present
When was the Riss glacial and what was the temp/sea level during this period?
108 000 years ago
Global temp reached a minimum of 7 degrees lower than present and sea levels dropped by +100m because more water was stored on land as ice
Raised beaches and example
Areas of former shore platforms that are left at a higher level than present sea level.
S. tip of the Isle of portman has a raised beach which was formed during the Tyrrhenian interglacial, 125 000 years ago
Marine terraces
They form in the same way that raised beaches do but they are much larger scale landscape features than raised beaches. This is because they are formed by similar processes that are acting over a longer period of time.
Unlike raised beaches they do not necessarily have cliffs above them.
Abandoned cliffs and example
Not uncommon to find them along emergent coastlines with wave cut notches, caves, arches and stacks
There is an abandoned cliff on the Isle of Portland
What has an influence on these landforms?
Weathering and mass movement. After their emergence, landforms are no longer affected by wave processes
Processes impacting abandoned cliff at isle of portland
Limestone at the top of the abandoned cliff is frost shattered due to periglacial conditions in the last interglacial.
The cliff face was gradually degraded by frost weathering processes
Periglacial processes like cryoturbation evident in limestone result of freezing and thawing of permafrost in the Pleistocene period
Modification in post glacial period due to weathering?
Further warming means that continued degredation with chemical weathering is likely e.g. carbonation of limestone cliffs
Biological weathering may become more significant with the colonisation of these landforms by marine organisms like whelks
Modification in post glacial period due to wave processes?
If temperatures increase sufficiently, these landforms would be closer to the coastline and therefore, subjected to wave processes again.
