Rotational Slip - mass movement
What is it?
Rotational Slip is a type of mass movement. Mass movement is defined as the downhill movement of rock and soil in response to the force of gravity. Rotational Slip is a down-slope movement of material that occurs along a surface. If the slip surface is curved, the side is called rotational.
Why does it happen?
Rotational Slip happens because water can build up in permeable soils and add weight to the basde structure.
As the water infiltrates into the permeable soils it adds weight. Other factoors like weathering and marine erosion take place which means the material loses its base strength and starts to move down the slope along a curved surface.
This leaves behind an exposed scarp face below the head of the slump, and producing a hummocky toe at the foot.
There are 3 kinds of rotational slip: Single Rotational Slide, Successive Rotational Slides and Multiple Rotational Slides.
What examples are there?
An example of a rotational landslide is the Holbeck Hall landslide, in North Yorkshire, England. The 1 million tonnes of cliff slipped as a rotational landslide over a two days in June 1993.