78 DESCRIPTION OF THE STRATA. 



eacii of them presents a different view of the series. The beds at 

 Wass bank are, generally speaking, harder, and lighter coloured, 

 than those at Rowlston scar; containing little or nothing of the yel- 

 low marl, which abounds in the latter place. At Whitestone cliff, 

 the beds are also hard, and contain little of the marl; and here the 

 upper part of the cliff, instead of being composed of a succession of 

 beds, as at the other two places, forms one immense bed, which 

 in some places is about eighty feet in thickness, if not more. This 

 massive bed, like the chalk, has a tendency to split verticallj^; and 

 large columnar fragments are successively detached from its perpen- 

 dicular face. Many of these fragments have fallen down into Gor- 

 mire, a small lake at the foot of the clifl'; while many others are lying 

 in ruins on the slope that forms its bank. In some places, the heap 

 of detached materials covers a great part of the front of the cliff; and 

 here some columnar masses of vast size may be seen. One block, 

 which the authors observed, might be about eighty or ninety feet long, 

 forty or fifty broad, and twelve thick. At the top of the precipice 

 stands a huge wall of the same rock, already parted from the rest of 

 the bed by a deep longitudinal chasm, and threatening ere long to 

 fall headlong into the valley, over which it now frowns. 



After stating these facts, it is scarcely necessary to add, that 

 this bed is remarkably hai'd and compact. It is siliceous, as well as 

 calcareous; yet it is most proper to call it a limestone. Its general 

 colour is ash gi'ey; its structure partly oolitic, paitly granular or 

 coarsely crystalline, with a mixture of dull earthy matter. Its im- 

 perfectly oolitic sti-ucture, which it may derive from its immediately 

 following the oolite, may entitle it to rank with the blue and grey 

 limestone, some varieties of which it resembles in colour; but in 

 other respects, especially in its crystalline structure, it differs con- 

 siderably from all the varieties of that rock elsewhere observed. 



