Chale Flashcards
Where is Chale located on the Isle of Wight?
Chale is located just West of the Southern tip of the island.
Describe what level of erosion is occurring at Chale and why nothing is being done about it.
It is the area of the island open to the most aggressive erosion, however nothing is being done to prevent erosion due to it being owned by the National Trust and the requirement to leave the area in it’s natural state. The rate of erosion can be anywhere between 1m and 5m per year. Sea levels are slowly rising and this is increasing the rate of erosion in this area. It is one of the highest points on the island which also leads to increased erosion.
Describe the geology and the types of failures occurring in the Chale region.
The ground make up mainly consists of the greensand formation commonly seen around the Isle of Wight as well as the gault clay. The greensand forms sets of discontinuities which help to isolate blocks causing falls. The gault clay is fairly stiff with low permeability and low residual strength leading to sliding failures on shallow angles. These failures also result in the formation of mud flows.
What is the local name for the gault clay which can be seen at Chale and throughout other regions of the Isle of Wight?
The gault clay is commonly known as the “blue slipper” due to it’s low residual strength and it being the cause of many sliding failures.
What attempts have been made to stabilise the cliff at Chale and why has it not worked?
Attempts to stabilise the cliff have mainly included planting small trees such as saplings in the hope that the roots may provide some stability. However, these have proven to be too small to really work. Vegetation is often used as a mitigation measure as it helps to decrease the water content in the soil and therefore increases the soil strength.
