FIRESTONE OF SUSSEX. 
163 
beds of chalk marl is the only proof of its pre- 
sence. It is not until we approach the Adiir that 
its characters are sufficiently developed to merit 
attention. It may be observed at Edburton and 
Poynings ; and at Steyning, which stands near the 
northern escarjiment of the Downs, to the west of 
the Adur, a bluish grey marlstone emerges from 
under the chalk marl, and forms a terrace of in- 
considerable breadth ; this is the first ajipearance 
of that variety of the firestone which, in the west 
of Sussex, is called “ malm rock,’’'’ and which, in- 
terposed between the chalk marl and the gait, must 
be regarded as the ecpiivalent of the more arena- 
ceous strata of Southbourn. This variety of the 
firestone was first jiointed out to me by John Haw- 
kins, Esq. F.R.S., of Bignor Park, a gentleman to 
whom I am indebted for much interesting inform- 
ation relating to the geology of Sussex, and whose 
contributions to' geological science, form so import- 
ant a feature in the Transactions of the Geological 
Society of Cornwall. Mr. Martin of Pulborough, 
in his Geological Memoir of a Part of 'Western 
Sussex, observes that “ the transition from the 
pure chalk to the malm is through an intermediate 
chalk marl ; its outcrop is obscure, and does not 
form a country distinct from the other chalk beds, 
nor is it quarried for domestic purposes ; but when 
accidentally opened, is found to abound in a great 
variety of marine fossils. This marl passes into 
the maliUj of which there is a thin stratum, suc- 
ceeded by a bed of green sand, and that by the 
more indurated malm rock, which again gradually 
M '-2 
