Miscellanies. 163 



fresh water origin ; while in others they are marine. Now it is ob- 

 vious that the strata which contain marine bodies only, must have 

 been deposited under very different circumstances to those which 

 contain fresh water fossils ; hence we* have two natural divisions — 

 namely, the marine, and the fresh water formations. The chalk, 

 and the sands and maris associated with it, belong to the former ; 

 the weald clay, and the sand and sandstones of the interior of the 

 country, to the latter. The subordinate divisions of the strata refer 

 principally to their mineralogical characters. There are also beds 

 of gravel, sand, and clay, containing boulders, &;c. the debris of the 

 regular deposits, and which, although of vast antiquity, are of far more 

 recent origin than those on which they repose ; these contain bones 

 and teeth of large terrestrial quadrupeds. 



The strata are grouped, and named as follows, beginning with the 

 uppermost or newest bed. 



Alluvium. — The silt, clay, sand, gravel, &;c. formed by the rivers 

 now in action. Lewes Levels afford a familiar example. 



Diluvium. — Sand, gravel, Sic." containing the debris of older for- 

 mations, bones of the horse, elephant, deer, whale. Sic. The cliffs 

 between Brighton and Rottingdean are dUuvial. 



Tertiary Strata. — These consist of regular beds of sand, clay, &,c. 

 resting on the chalk, and are characterised by their organic remains. 

 Castle Hill, at Newhaven, Bognor Rocks, Clay at Brackleshara, are 

 examples of these strata. 



Chalk Formation. — This comprises, 



1 . The chalk, with and without flints ; it forms the Sussex, Hamp- 

 shire, Surrey, and Kent Downs. 



2. Grey marl, forming the base of the Downs, and generally ap- 

 pearing on the loeald escarpment of the chalk ; at Hamsey, Stone- 

 ham, and Southerham there are marl pits, where the usual fossils 

 occur. 



3. Gait,* or blue chalk marl, a stiff blue clay ; its fossils have 

 their shells beautifully preserved. It is seen, at Ringmer, near 

 Lewes ; and on the road-side from Wannock stream to Eastbourn ; 

 at Newtiraber it appears under the grey marl. 



4. Shanklin Sand, so called from Shanklin Chine, in the Isle of 

 Wight, where it is beautifully exhibited. This sand forms hills, that 

 rival the Downs in altitude in the west of Sussex ; near Lewes it oc- 



** A provincial term, used in Cambridgeshire. 



