The sediments exposed in the Bowmans trial pit were mapped and sampled in detail. The oldest formation recognised is the mid to late Eocene Clinton Coal Measures, which is represented by low rank, soft brown coal and unconsolidated, medium grained sand of varying carbonaceous content. Overlying this sequence is a 35 metre interval of sometimes partially consolidated, fine to very fine grained sandy sediments. The Hindmarsh Clay consisting of mottled very stiff to hard clays occurs at the top of the sequence.