Herne Bay

Location – area studied

General area

Detailed map of the area

Question 1 – Geomorphological processes

This section details different geomorphological processes that have been made on the cliffs.

Weathering – rock expansion

The area studied is in the north of Kent and east of London. It lies between Herne Bay in the west and Wantsum channel in the east. The cliffs on this part of the coast are subject to high rates of erosion making it ideal for study in this coursework.

Weathering – Granular disintegration

Physical Weathering and Chemical weathering

Granular disintegration is where rocks such as sandstone which are porous become saturated with water. Minerals inside the rock dissolve in the water and when the water evaporated the minerals form crystals inside the rock which push off flakes off rock. These flakes of rock have fallen down the cliff face and collected at the bottom of the cliff as shown in the photo.

Chemical weathering

When rain water runs down a cliff face (rain wash) over time it wears the rock creating rills, which are shown in the picture. When water freezes in these rills they expand as the water expands, this is called freeze thaw.

Rain water with dissolved carbon dioxide in it becomes acidic and will dissolve any rock which is more than 50% calcium carbonate such as limestone. Plant matter in the ground will increase the acidity of the rain water as more carbon dioxide dissolves into it. This process is called carbonation.

Iron in the rock has oxidised forming a red brown stain, this is oxidisation.

Biological weathering

Biological weathering is common on the cliffs as Sand Martins burrow holes into the cliff face.

Biological weathering

Coastal erosion

Roots of vegetation on the cliff force cracks to widen. This is biological weathering.

Swash traps air in cracks in the rock. As the water is sucked away through back wash the pressure put on the air is realised causing it to rapidly expand making a small explosion. This widens the crack and is called hydraulic action

The rocks littered around the cave entrance are picked up when the tide comes in and thrown at the cliff, eroding it. This is called corrasion.

Coastal erosion

Rock hit each other breaking off rock particles which smooths out the angular edges of the rocks. This is called attrition

Erosion and formation of the cliffs

The cliffs are constantly eroded by the waves from the sea. The factors that affect the force of the waves are the strength of the wind, how long it blows for and the distance it blows over. The cliffs of Herne Bay are exposed to a very large fetch, shown in the diagram below. The arrow represents a possible direction of the wind.

Once the wave reaches shallower water it will start to break and the swash will run up the beach and may reach the cliff, eroding it. The backwash will then drag beach material back down the beach.

According to the direction of the wind, beach material is moved up and down the beach; this is called long shore drift and is shown by the diagram on the left.

The waves undercut the cliffs and over time the raised section of the cliff will fall into the sea when there is no longer enough material underneath that section of the cliff to support it. Overtime the fallen material moves along the coast by long shore drift and is sucked into the sea by backwash.

Wave cut platforms

This picture shows the extent of the erosion to the cliff. The rocks lying on the beach is a wave cut platform where the cliff once was. However over time the geomorphological process acting upon the cliff has pushed it back. The wave cut platform is evidence that the waves have undercut the cliff leaving, the unsupported upper section of the cliff which then falls away revealing the wave cut platform.

Resultant landforms

Cave

Arch - in the future after further erosion the pillar or cliff in the middle may become a stack which there is currently none of at Herne Bay

exam