The Gault Formation is a fossiliferous grey clay, which is only exposed where it
has been dug for brick-making. Former clay pits are mostly overgrown, backfilled
or flooded. The only exposure (illustrated) is on private land associated with Pitsham
brickworks near Midhurst. Access is not permitted and fossils are very rare. The
former clay pit at Small Dole (a landfill site for many years) produced abundant
fossils, including ammonites, belemnites and many other marine fossils.
The Upper Greensand is exposed in sunken lanes and river cliffs to the north of the
South Downs. It is a grey, lime-rich, fine-grained silty sandstone with few fossils
(mostly bivalve sea shells). This exposure in the river cliff near Amberley Castle
is one place where the Upper Greensand can be inspected that isn’t at a roadside.
Upper Greensand is best seen in the many churches along the outcrop of the rock.
It often weathers with a brown surface over the grey stone beneath. This church at
Elsted has both grey and brown-weathering Upper Greensand. The village of South Harting
is predominantly built of this stone.
Malmstone or clunch
The Upper Greensand of West Sussex is correctly given a traditional common name of
malmstone, malm meaning ‘chalky rock’. It is also incorrectly called clunch in the
description of building stone. Clunch is strictly a type of chalk, the name having
been applied to the lower beds of the Chalk in East Anglia and Cambridgeshire. It
has also been used to describe a chalk from near Lewes.
Clunch (geologically) is not Upper Greensand and use of the word in West Sussex is
not appropriate. Malmstone is a perfectly acceptable name!