Pinnacle nature reserve

Geological History

Sandy Pinnacle is an outcrop of the Lower Greensand, a sedimentary rock deposited about
100 million years ago on the bed of a warm shallow seaway. Some of the sand came from as
far away as Yorkshire, carried by rivers. Harder Sandstone rocks have been left standing above
the surrounding clay landscape by erosion. During the Ice age a river cut down through the
exposed Greensand ridge here and there is also a dry valley where a small river flowed over
the permafrost present at that time. The wide flat Ivel valley can be seen from the top of the Pinnacle. This valley was formed during the ice age when the Ivel was swollen to many times its present size by melt waters, this is why the valley is much wider now than the river needs it to be.
The Pinnacle Today
Today the exposed Lower Greensand is rapidly eroding as the sand is washed down the steep slopes; this is accentuated by people straying from the recognised paths. The bare sand and exposed rock faces provide important habitats for solitary bees and wasps and close inspection of any exposed areas will reveal numerous small holes, particularly in the summer. The dry valley is now wooded with numerous large trees and plenty of dead wood for invertebrates to feed on. The flatter open areas have a typical acidic grassland community present because of
the soil conditions created by the underlying Lower Greensand