On day one, we analysed the areas of East Prawle to Start Bay, and noted key evidence that shows how geomorphic processes are able to shape a natural landscape over time. Such as weathering, erosion, transportation and deposition. Through doing this we could get a better understanding of how and why the coastal area between these two points had drastically changed so much, and could therefore answer the question “How had the physical landscape developed along the coastline between Prawle Point and Start Bay”. Through noting the key processes that were continuously shaping the landscape it could even help us understand how some of the sites we saw, such as Gammon Head and Langerstone Point may look in the future.
Here is a map of the south-east of England, which is highlighting the route from Prawle Point (green) to Start Point (red).
Before we started analyzing the geomorphic processes which are currently shaping the landscapes we viewed, we would first need to note how the waves which help determine the formation of certain landscapes through the process of erosion, are actually formed.
Definition of “fetch”
Fetch, is the geographic term for the length of water due to the strength of prevailing winds. Due to the fetch playing a large role in determining the size and strength of waves, it is often associated with coastal erosion and the process of long shore drift.
The fetch length plays a key role, along with wind speed in determining the size of a wave, being that the longer the fetch and faster the wind speed, the larger and stronger the wave will be. The fetch length determines the power and energy of the wave. If a fetch is very large, then the wave will be very large. If the fetch is very small, the wave will be small. The fetch is related to the orbit of the wave. In the UK most waves origin from the south-west and is where some of the largest waves come from towards the coast.
Gammon Head is one of the various sites which we viewed. It was very useful in helping us understand the significance of these geomorphic process that shape a natural landscape, due to it revealing many present day evidence along its surface.
Here I have analysed and highlighted the key noticeable points of gammon head:
Gammon Head formation
Now that you can see the present day evidence that geographic processes have taken place over Gammon Head (over many years), we would need to know just how this process of erosion actually occurred formed gammon head over time. Here I have sketched a rough diagram explaining the formation of Gammon Head due to continues erosion.
Here is a layout of the south-east of England, with two different colours representing the areas situated around Devon with the majority of the rocks being sedimentary (red) and metamorphic (yellow).
How it was formed
The headlands and bays of Gammon Head were formed due to the levels of resistance from the different types of rock within the cliff. The softer, sedimentary rock was gradually worn down whilst the more resistant metamorphic rock was left protruding outwards, due to it having a greater resistance and therefore a slower rate of erosion. This meant that the worn down bays and the remaining headlands still stand today and can be easily noticed when visiting Gammon Head.
Gammon Head processes
Now we know how the headlands and bays on Gammon Head have been formed due to erosion we will need to know how other processes such as weathering currently affect the landscape. Here is a simple sketch of the current weathering processes which act on Gammon Head.
Gammon Head – Present Day
Future of Gammon Head
Through knowing how the present day appearance of Gammon Head has been formed, such as its headlands and bays, and the other weathering processes which currently are acting on it, we can get a better understanding of how Gammon Head may look like in the future, with these various processes determining what it will look like. Here is a simple sketch of how Gammon Head may look like in the future.
From Gammon Head we walked to Langerstone Point. Langerstone Point was a n excellent present day example showing how a wave cut platform can eventually be formed due to changes in sea levels over many years. Here is a diagram of Langerstone Point present day.
Langerstone point – brief layout diagram
Langerstone Point formation
Now you can see the how Langerstone Point currently looks like at this present day, we need to know exactly how it was formed over time. Here is a simple sketch showing the formation of Langerstone Point and the wave cut platform its presents.
How it was formed
A general wave-cut platform is formed due to a large cliff continuously being eroded at its base, called the wave-cut notch, with it eventually collapsing over and overt again as it retreats back. However it is the changes in the sea level which determine the point of the rock which leads it to collapse therefore leaving behind different layers of rock – a wave cut platform.
Future of Langerstone Point
Langerstone Point has been formed due to changes in sea level therefore it is the sea levels will also determine how it is shaped in the future. Here are two sketches of Langerstone Point in the future, one if sea levels were to rise and one if sea levels where to fall.
If sea levels rise
If sea levels were to rise in the future then the top layer of the wave-cut platform would eventually be eroded completely, leaving behind only one layer and the cliff.
If sea levels fall
If sea levels were to fall in the future then another layer would form on the wave-cut platform, meaning there would be three different layers aswell as the cliff itself.
From Langerstone Point we walked to sharper’s Head, and again noted the factors which determined its present day features over time, and noted how crucial they are in determining how the landscape changes in the future.
How it was formed
Sharper’s Head was formed during the final portions on the great ice age thousands of years ago. The ice that was formed carried many large rocks over huge distances and eventually deposited them when the ice melted, by sharper’s cove, leaving behind the rocks to form Sharper’s Head (with the rocks all facing the same direction).
Slapton Sands – Longshore Drift
Longshore drift is the movement of eroded material, in a shark fin shape way, along the coast line. The effect of this is determined by factors such as the direction and fetch of the present wind and, in the long term, of the prevailing wind. Waves striking the shore at an angle as opposed to straight on will cause the wave swash to move up the beach at an angle. The swash moves the sediment particles (typically sand or shingle) up the beach at this angle, while the backwash brings them, solely under the influence of gravity, directly down the beach. This has the net effect of gradual movement of the particles along the shore by the use of swash and backwash.
In the past sea levels were generally much higher then they are nowadays. During the last ice age, the sea retreated back, revealing a seabed, which is still clearly visible today. Various types of rocks can be found on the beach of Slapton Sands that were once 40km out in Start Bay at the end of the last ice age. When the last ice age ended, the sea levels rose, which meant that various rocks were pushed back to the land. This is where they were eventually deposited, and therefore creating a barrier breach.