25G Dr. Berger on the Geology of some parts 



Isle of Wight, where It lies between a stratum of loose quartzose 

 sand, and one of calcareous freestone with chert, above the source of 

 an alum chalybeate spring. It is found also to the north-east of Alum 

 bay, where it alternates with sand ; at High Cliff in Christchurch 

 bay, where it constitutes most part of the cliff, and is covered only 

 by the flint-gravel ; and between Encombe and St. Aldham's Head 

 in the Isle of Purbeck. 



(b) Marl of a bluish-grey colour, intermixed with iron-pyrites. 

 It has a degree of lustre, its texture is slaty, it feels smooth and 

 greasy, does not contain mica, and is not acted upon by acids ; it 

 falls in water into a very fine powder, but not so readily as the for- 

 mer variety: when heated it becomes harder, of a yellowish colour, 

 ■and its structure appears more evidently foliated. I have observed 

 it in the bed of a rivulet which runs to the sea near Compton-field, 

 on the west-south-western coast of the Isle of Wight, not far from 

 Brixton bay. The flint gravel lies over it. 



(c) Marl of a greyish-white colour, harder than the two former 

 varieties, effervescing with acids, and adhering more strongly to the 

 tongue. In water it does not fall into powder ; the fracture is 

 earthy ; no specks of mica are visible in it ; when heated to redness 

 it does not decrepitate, but becomes harder, and of a reddish-brown 

 colour. The surface is often covered with compressed nodules of 

 sulphuret of. iron ; it alternates with the preceding kind. 



(d) Marl of a bluish-grey colour effervescing with acids ; its 

 fracture is dull and earthy ; it contains a great many shells and a 

 few specks of mica. In water it does not fall into powder ; it 

 hardly adheres to the tongue ; when heated, it decrepitates slightly, 

 and the texture becomes more evidently slaty ; by a red heat it 

 acquires a white-reddish tinge, and gives out a bituminous smell 

 analogous to that of the Kmcridge coal, or to express myself more 



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