Geography CP&L: Coastal Landscapes Development Flashcards
Bays and Headlands - Landforms of Erosion
Areas with alternating more and less resistant rocks are a common feature of many coastlines. Initially erosional processes predominate in areas with less-resistant rock, forming bays, leaving the more resistant rock protruding out to sea as headlines. Because of refraction, the headlands then receive the highest - energy waves and are more vulnerable to the forces of erosion than the bays. The bays experience low-energy waves that allows sediment to accumulate and form beaches. These then act to protect that part of the coastlines e.g. concordant coast of San Francisco Bay.
Cave Formulation - Landforms of Erosion
(1. C, A, S, S)
Selwick Bay and Flamborough Head
On any cliff line it is the weakest parts, such as cracks, fissures, joints and bedding planes that are attacked by the sea. The sea will undercut the cliff and create an cave. This is through a combination of wave pounding, wave quarrying and abrasion.
Arch Formulation - Landforms of Erosion
(2. C, A, S, S)
Selwick Bay and Flamborough Head
If the cave on the side of the headland, it will extend backwards to meet another side of the headland due to wave refraction concentrating energy into the caves. Eventually the conjoining caves will create a hole all the way through the headland which is called an arch.
Stack Formulation - Landforms of Erosion
(3. C, A, S, S)
Selwick Bay and Flamborough Head
As the cliff recedes and the wave cut platform develops, the arch loses support due to the combination of marine erosional processes from below and sub-aerial weathering from above. This will result in the top of the arch collapsing leaves an isolated portion of rock called a stack.
Stump Formulation - Landforms of Erosion
(4. C, A, S, S)
Selwick Bay and Flamborough Head
The sea will continue to erode the base of the stack and exploit the abstain and wave cut notch. The top of the stack will continue to be subject to sub-aerial weathering. Over time, the stack will collapse and leave a small portion of rock on the wave cut platform, This is a stump.
Initial erosion (discordant coastline) - Landforms of Erosion
(1. B & H)
Dorset Coastline
Discordant coastline occurs where bands of differing rock type run perpendicular to the coast. The differing resistance to erosion leads to the formulation of headlands and bays.
Headland Formulation - Landforms of Erosion
(2. B & H)
Dorset Coastline
Headlands are formed from hard rock, that is more resistant to erosion, such as limestone, Headlands form along discordant coastline where bands of soft and hard rock outcrop at a right angle to the coastline.
Bay Formulation - Landforms of Erosion
(3. B & H)
Dorset Coastline
Alternating layer hard and soft rock allow the same to erode the soft rock after, forming a bay but leaving hard rock sticking out, known as a headland. The alternating rate of erosion of hard and soft rock is known as differential erosion.
Feedback Formulation of Bays and Headlands - Landforms of Erosion
(4. B & H)
Dorset Coastline
This exaggerates the change making the system more unstable and taking it away from dynamic equilibrium due to erosion and transportation of sediment.
Positive Feedback: Moving away from equilibrium
Negative Feedback: Moving towards equilibrium
Initial erosion (concordant coastline) - Landforms of Erosion
(1. Cove)
Lulworth Cove
Formulation began after last ice age. A river swollen by melted water flowed to the sea. The river cut a valley and breached the Portland shore. The rising sea flooded into the valley and stated to exploit joints and weakness in the Purbeck Beds.
Impact of River - Landforms of Erosion
(2. Cove)
Lulworth Cove
Erosion the occurrence of the soft Wealden Clay, which had already been scoped out by the river.
First Cove Formulation - Landforms of Erosion
(3. Cove)
Lulworth Cove
The cove formed as a pan shaped inlet. The cove continued to enlarge, eroding through the Greensand rock.
Final Cove Formulation - - Landforms of Erosion
(4. Cove)
Lulworth Cove
Erosion was contained and slowed down by the semi-hard chalk beds to produce the semi landlocked cove of today.
Simple and Compound Spits - Landforms of Deposition
A spit is a long narrow feature made of sand or shingle that extends from the land into the sea (or part of the way across and estuary). Spits form on drift-aligned beaches. Sand or shingle is moved along the coastline by longshore drift but if the coastline suddenly changes direction (e.g. because of a river estuary), sediment begins to build up across the estuary mouth and a spit will form. The outward flow of the river will prevent the spit from exuding right across the estuary mouth. The end of the spit will also begin to curve around as wave refraction carries material round into the more sheltered water behind the spit.
A Compound spit occurs where the transport processes are available over time, which produces a series of ‘barbs’ along the spit.
Tombolos Formation - Landforms of Deposition
A Tombolo is a beach (or ridge of sand and shingle) that has formed between a small island and the mainland. Deposition occurs where waves lose their energy and the Tombolo begins to build up. Tombolo may be covered at high tide, for example at St Ninian’s in the Shetland Islands and at Lindisfarne in Northumberland. Chesil Beach is also an example of a Tombolo linking the Isle of Portland with Weymouth on the mainland.
Bars (Barrier beaches/Islands) - Landforms of Deposition
Where a beach or spit extends across a bay to join two headlands, it forms a barrier beach or bar. The barrier beach at Start BAy in Devon is 9 km long and is formed from rounded shingle deposits (consisting mostly of flint and quartz gravel). Barrier beaches and bars can also trap water behind them to form lagoons such as Slapton Key.
Offshore Bar - Landforms of Deposition
Also known as sandbars, offshore bars are submerged (or partly exposed) ridges of sand or coarse sediment created by waves offshore from the coast. Destructive waves erode sand from the beach with their strong backwash and deposit it offshore. Offshore bars act as both sediment sinks and potentially sediment input stores. They can absorb wave energy thereby reducing the impacts of waves on the coastline.
Embryo dunes - Landforms of Deposition
(1. Sand dune)
Formby Point, Sefton Coast
To begin the psammosere succession, sand blown on shore needs to be trapped by an object. This could be rocks or driftwood. Embryo dunes are just above the high-water mark. They retain little water and have few nutrients resulting in only Pioneer species can grow here e.g. grasswort
Foredunes - Landforms of Deposition
(2. Sand dune)
Formby Point, Sefton Coast
Foredunes are embryo dunes that have started to become colonised by an increasing number of Pioneer plants. Pioneer plants trap sand in their leaves and roots consolidate the sand. When they dies, they increase the amount of humus (organic matter) in the sand dune.
Yellow Dunes - Landforms of Deposition
(3. Sand dune)
Formby Point, Sefton Coast
Yellow dunes are above the level of the highest spring tides,, they have a higher amount of humus and are less exposed to strong winds. All of these factors means that plants do not have to be specialised as Pioneer species to colonise for example Red Fescue or Marrow Grass
Grey dunes - Landforms of Deposition
(4. Sand dune)
Formby Point, Sefton Coast
Grey dunes are named after their colour. They are grey because of the significant increase in humus (dead plant material) within them. There is a complex vegetation coverage enabling a range of plants to exist. pH has decreased so diversity can increase e.g. Heather, Harebells
Plagioclimax - Landforms of Deposition
(5. Sand dune)
Formby Point, Sefton Coast
As the salt marshes, sand dunes can reach climatic climax vegetation for the Uk (mixed Oak woodland). The soil here is acidic due to the increased nutrient content. Difficult for sand dunes to reach climatic climax vegetation in the UK as sand dunes are fragile and controlled by humans so they only reach Plagioclimax ( usually heather land)
Formulation of Blowouts - Landforms of Deposition
(Sand dune)
Formby Point, Sefton Coast
Blowouts are created if there is a gap created in the vegetation, for example from a rabbit burrowing. They can occur at any stage of the succession. Once a bare patch is created it is difficult for plants to colonise as area lacks nutrients.
Formulation of Dune Slacks - Landforms of Deposition
(Sand dune)
Formby Point, Sefton Coast
Created if there is a low point in the dunes. This could be because, when the dunes were initially created, a new embryo dune developed a significant distance away from the fore dunes. Can have water in them because can be at the same level of the water table.
Initial conditions needed - Landforms of Deposition
(1. Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
Most Mudflats do not develop into salt marshes because of the specific conditions needed for this to occur e.g. halophytic plants need to not destroy the system)
Development of the Mudflats - Landforms of Deposition
(2. Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
Mudflat develop on sheltered shorelines that are not exposed to powerful waves - they are associated with low energy environment such as estuaries and on the landward side of Spits. Mudflats form as a result of a process called flocculation. The Saltator then mixes with the slow-moving water of the Stuart that carries lots of suspended sediment.
From Mudflats to a lower Saltmarsh - Landforms of Deposition
(3. Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
Once the mudflat has been formed, it can be colonised by specific by specific halophytic (slat-tolerant) plants. Pioneer species (such as Grasswort, Eel grass and Cordgrass) are plants which colonise a new area of bare soil or rock and can survive the harsh conditions. Can live in the high salt concentrated conditions.
From Lower Saltmarsh to Upper Saltmarsh - Landforms of Deposition
(4. Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
As plants continue to grow, trap mud and die, the height of salt marsh increases. As a result, the marsh is not submerged by salt water daily and therefore is an increase in soil nutrients from the decaying plant matter. Therefore, less specialised plants are able to grow, increasing the biodiversity of the salt marsh.
Climatic Climax Vegetation - Landforms of Deposition
(5. Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
Once the salt marsh has stabilised they can reach climatic climax vegetation for the Uk (mixed Oak woodland). The soil here is acidic due to the increased nutrient content. Difficult for Saltmarsh to reach climatic climax vegetation in the UK as Salt Marshes are fragile and controlled by humans so they only reach Plagioclimax ( usually heather land)
Salt pans - Landforms of Deposition
(Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
Form where there is a depression or lack of plants in a small area of the salt marsh. Tidal water collects here with a slat content that increase as the trapped after evaporates.
Creeks - Landforms of Deposition
(Mudflats and Salt Marshes)
Welwick Salt marsh, Humber Estuary
Through the Saltmarsh form in a similar manner to rivers. They help the tidal water drain away from the Saltmarsh by taking the easiest route. As these creeks are still saltwater, Pioneer species can be found on their banks.
What is Flocculation?
(Mudflats and Salt Marshes)
Is where the sediment particles come out of suspension and clump together to form a floc. In the formulation of a mudflat,, this happens as a result of the suspended load mixing with saltwater.
