The Chasms have been exposed in recent times to the erosive power
of the sea. The deep fissures are cracks developing in the cliffs
where large sections are slowly slipping seaward, eventually to crash
into the sea.
The
cliffs at The Chasms are made up of many layers of sandstone originally
deposited on the sea bed in water depths of several hundred to thousands
of metres.
Each individual bed of sandstone is made up of quartz grains transported
from shallower water by submarine avalanches(turbidity
currents). As these slowed down they
dumped the material they were carrying forming a new layer of sediment,
in this case sand. The beds visible in this photograph represent a
period of geological time in the order of 100,000 years. Areas containing
thick quartz-rich sandstones (quartzites) similar to those at The
Chasms are shown with yellow and orange colours on the accompanying
Geological map. After
480 million years of burial, deformation and uplift.
