Geologically the cliff consists of mudstones and sandstones of the Porthtowan Formation and slates/siltstones of the Mylor Slate Formation, both of Devonian age.
These rock materials are weathered and have variable strength.
There is a complex interrelationship of regional faulting and local jointing which allows the rock mass to divide into blocks which with time become unstable.
The rock material that failed, at least on the evidence of the video, appeared to be in a dry state.