Geology of the Neighbourhood of Weymouth, Sgc. 41 



grey marl and marlstone to assume a position partly vertical and partly tor- 

 tuous, between horizontal beds of grey marlstone on the one side, and of 

 inferior oolite on the other. These appearances may in part be due to sub- 

 sidence superadded to the fault; the point of the cliff in which they occur 

 is so much exposed to the action of the waves, that it may ere long be 

 totally removed, and the appearances represented in our section be entirely 

 changed. 



It should be observed that not one of all these faults appears to have been 

 produced during- the formation of the strata : not one is covered at its summit 

 by any overlying substance except diluvium ; and that those in the eastern 

 part of our district were evidently not produced until the time at which the 

 chalk and all the strata subjacent to it, in this district, underwent a simulta- 

 neous elevation. 



V. Denudation producing Valleys. 



In a country that has been the scene of such tremendous convulsions and 

 subterranean disturbances, it was probable that we should find on the surface 

 abundant ruins, and dislocated fragments of the rocks that have been sub- 

 mitted to such violence ; we should expect to discover masses of rubbish such 

 as we see in the wreck of modern land slips, and which cannot but have been 

 created in prodigious quantity along the line of the elevations and fractures 

 we have been tracing: but on examination we find that all this wreck has 

 vanished, and been so totally swept away, that scarce a trace of it can be 

 recognised throughout the whole district which it must once have covered. 



It is obvious, from a mere glance at the Map, that the strata originally 

 occupied larger areas than they cover at present; and that if no further opera- 

 tions had taken place in the Vale of Weymouth beyond the elevation and frac- 

 tures we have described, we should have had little more than a series of arches 

 piled successively on one another, and extending over a large portion of the 

 whole district; the angle at which the strata rise being in many parts so 

 small that no very distant separation of the fractured parts could have attended 

 their elevation; and thus the central cornbrash of the Vale of Weymouth 

 would have been arched over with bending strata of Oxford clay, coral rag, 

 Kimmeridge clay, and Portland stone ; and the Vale of Bredy and the Brid- 

 port district would have been covered by nearly horizontal beds of greensand 

 and chalk, connecting the great greensand escarpment of the north and east 

 of the Vale of Bredy and Abbotsbury Castle with the outlying summits of 

 Swyre Knoll, Shipton Beacon, Eype Down, Golden Cap Hill, Lewsdon Hill, 

 Lambert's Castle, and the entire group of insulated caps and ridges of green- 



VOL. IV. SECOND SERIES. G 



