IGCSE Coasts - Landforms

Similarly to waterfalls and gorges, hydrolic action attacks and erodes the bottom of the cliff. This erosion will eventually make a wave cut notch (a hole at the bottom of the cliff). As this gets bigger, the weight of the rock above will increase and eventually the cliff will collapse. This process happens repeatedly and the cliff retreats, leaving a wave cut platform which can only be seen at low tide. Wave cut platforms are made in a similar ways to waterfalls and gorges (rivers topic). 

http://a19.video4.blip.tv/2370000589120/RCha-CoastalErosionFeatures854.flv?ri=7825&rs=1331

These are found on headlands where erosion is hitting the feature an all three sides, mainly by wave refraction. This is when waves look for weaknesses in the headland (cracks, joints, bedding planes) and begin to attack it using hydrolic pressure/action. This turns the crack into a cave, then an arch (as it cuts through the headland), then the arch grows causing the roof to collapse and leave a stack. The stack is then eroded by the sea and weathered in the air, leaving a stump.

Bays and headlands are formed similarly to rapids. When you have alternate layers of soft and hard rock the sea is able to erode the soft rock much quicker, making a bay. And leaving the harder rock to form a headland. 

Headland: A piece of land that sticks into the sea. Waves refract around headlands causing them to expeirience lots of erosion, creating further costal features. 

Bay: An indented area of land found normally between two headlands. Beaches are often formed in bays as there is less erosive and more depositional features.

Beaches are an accumilation of sand, shingle and/or pebbles between tidal range (high and low tide). They recive their material from LSD (longshore drift) from constructive waves but also from cliff erosion and river discharge. 

The structure of a beach typicaly can be divided into backshore -area above the normal tide level-, offshore - area below normal low tide- and foreshore - the area inbetween normal and low tide. 

Sand dunes are very dynamic, they are an extention of the beach and are formed by dry sand being blown up the beach. 

They consist of 5 types of dunes. 

The Embro Dune: There are the dunes closest to shore, forming in sheltered areas. 

Foredunes: The embro dunes can join to make foredunes, these tend to be yellow as thay have limited vegitiation - no real humus layer. 

Yellow dunes: These are more stable and can grow more as marram grass and sea couch grows on them, developing a humus layer. 

Grey dunes: The humus layer changes the colour of the dune from yellow to grey 

Mature dune: This dune sustains more plants, flowers and trees. 

Marsh plants can grow in the dune slack where water is collected between the dunes. Humus is the layer of decaying plant and animal matter that adds nutrients to the ground. The changing of types of plants is known as sucssesion. The water table is the line between saturated and unsaturated ground. 

These are usually found behind spits, on low energy coatlines, where deposition exceeds erosion. The continued deposition means that mudbanks are formed and exposed at low tide, allowing salt and grass to grow - forming a salt marsh. 

These are all made up of a combination of LSD and deposition, and are known as depositional landforms. 

A Spit is a long thin stretch of sand that connects to the mainland but stretches into the sea. They are formed in more calm areas of water, and where the coastland changes direction (creating protection). LSD occurs in the dirrection of the dominant prevailing wind and when the coastline changes direction the LSD doesn't, and continues out into the sea. Because of the lack of energy in the sea, deposition occurs rather than transportation and overtime a spit is created. The end of a spit will usually be hooked because of the occasional winds and storm which blows in the opposite direction of the prevailling wind. 

Tombolo: a spit that joins the mainland with an island. 

Bar: A spit that connects two headlands or runs across the face of a small cove (bay).

Lagoon: The salt water lake that develops behind the bar. Overtime the lagoon will become smaller as deposition takes place.