Submergent Landforms Flashcards
Impact of rising temp on ice stored on land and sea level
It leads to higher rates of melting ice stored on land as ice sheets and glaciers, causing an increase in the volume of water in the ocean store and rise is sea lvl
The relationship between temp and water molecules
As temp increases, water molecules increases causing an increase in volume and sea level
1 degree increase in temp= 2m increase in sea lvl
When was the Würm glacial period and how did the temp impact sea levels?
What is the flandrian transgression?
25 000 years ago
Temp was 9 degrees lower than today and the sea lvl was 90m lower than present
The period of significant sea lvl rise from the Würm period to now
What are rias and how do they form?
They are submerged river valleys which form as the sea lvl rises. The lowest part of the rivers course and the floodplains may be completely drowned.
Rias features
Exposed valley sides are gently sloping formed by fluvial erosion in the channel and sub aerial processes on valley sides
Typically underlain by alluvial deposits that were eroded by rivers during the Pleistocene Period
Example of rias. When was it formed
Found at Salcombe, Kingsbridge. Formed during the Flandrian transgression
What are fjords? Example of a fjord in Norway?
Submerged glacial valleys. They have steep, cliff like valley sides and water is uniformly deep, often reaching +1000m
Sogne Fjord is nearly 200 km
Cross section of a fjord? Example of fjord
U shaped which reflects the original shape of the glacial valley. Consists of a glacial rock basin with a shallower section at the end.
Results from lower rates of erosion at the seaward end where ice thinned in warmer conditions.
Example: milford sound, new zealand
Why did erosion rates remain high in fjords? Sediment deposition?
The water was/is very deep (+1000m) during the flandrian transgression, causing fjords to deepen.
Melting glaciers on the south coast of the south island of New Zealand have deposited sediments, causing the volume of sediments to increase.
Chesil beach tombolo formation
Sediment carried into the English channel by melting water in the Würm glacial accumulated in locations like Lyme Bay.
Sea lvl rose causing sediment to be carried NE by prevailing winds which transported it 50 km until it became attached to the Isle of Portland on one end and the mainland on the other end.
How much shingle is on chesil beach tombolo and what are the different sizes
100 million tonnes of shingle
Varies in size from 1 cm pea sized material to 7 cm pebbles
What might rias and fjords be impacted by in the future?
Wave processes acting on their sides as well as sub aerial processes which may cause a reudction in the steepness of valley sides in fjords
Impact of marine erosion on rias and fjords
Likely to increase due to stormier weather. Sea levels are predicted to rise 0.6m in 100 yrs
Impact of LSD and sea level rise on chesil beach
Very vulnerable to LSD as it is unconsolidated.
Sea lvl rise could cause shingle to be moved more NE (currently moving at 17cm/yr)
Breaches of the tombolo are likely due to future storm events. Recent waves have topped the beach.
