TILVESTER HILL. 
177 
tions of ironstone. These beds are peculiarly inter- 
esting, from the abundance and variety of their 
organic remains ; which consist of casts of shells of 
the genera Venus, Trigonia, Gervillia, Thetis, Mo- 
diola, &c. 
A bed of calcareous grit, which sometimes passes 
into a blue limestone, occurs at Dean Farm, near 
“ Petworth, and may be traced to Stedham, Kogate, 
“ Lyss, Pleadley, and Godaiming: in the last-men- 
“ tioned localities, the grit is a conglomerate of 
“ quartz grains and pebbles, held together by a 
“ calcareous cement, and is called JBargate stone”* 
This bed extends eastward through Surrey and 
Kent. Mr. Murchison observes, that the lowest 
beds of the sand are marked by a great change of 
appearance ; green particles jirevail in the mass, and 
all the hills immediately adjoining the valley of the 
AVeald clay afford a yellowish sandstone, filled with 
green particles, which is used for building, and is 
the only bed of theShanklin sand formation, west of 
the river Arun, that has been observed to contain 
shells, or rather casts, — probably of ammonitmand 
terebratuhr. 
Tilvester Hill, on the south of Godstone, in 
Surrey, presents a most interesting section of this 
formation ; and as the main road from London to 
Lewes passes directly over it, and a considerable 
fault or displacement of the strata is exposed on the 
road-side near the to]), this locality generallyattracts 
the notice of travellers. For this reason, as well as 
• Mr. Murcliison, in Geolog. Trans, new series, vol.ii. p. 101. 
