10G GEOLOGY OF THE ISLE OF WIGHT. 



G. Fine sand with comminuted sheila . . . 6 feel. 



7. Compact grey limestone; termed siliceous 



limestone by Mr. Webster, from its con- 

 taining a large proportion of sand ; but 



few fossils were observable 2 feet. 



8. Fine sand. "Water issues from this bed, 



being thrown up (according to the quarry- 

 men) by underlying beds of clay. 



The upper beds of limestone abound in casts 

 and impressions of shells. No. 3, is full of hollows 

 left by the decay of the shells, and the subsequent 

 separation of the casts of their cavities. This bed 

 appears to have been formed by the infiltration of 

 calcareous matter into a layer of shells, the moulds 

 and casts of which are now cemented together by 

 sparry concretions. A coating of white powder 

 on the casts is almost the only vestige of the con- 

 stituent substance of the shells now observable. 

 In this sparry limestone the minute seed-vessels 

 of charw hereafter described, fragments of bones 

 of turtles, and casts of planorbes (PL I. fig. 1) and 

 limnei (PL I. fig. 3) are abundant. 



The sand, No. 6, is intimately mingled with 

 comminuted shells, the whole being loosely held 

 together by an infiltration of marl ; the most 

 coherent masses readily crumble into powder 

 between the fingers. I have not succeeded in 

 obtaining a single shell entire; but from a micro- 



