438 W. WAitake) — Raised Beach at Portland. 



reacli of denuding actions, are of a softer and more destructible kind 

 tlian those that overlie them. 



There are three facts that seem to confirm the theory that the 

 channel in the rear of the Chesil Bank has been formed since the 

 heaping up of the shingle : — they are (1) that the isolated part of 

 the bank is also the largest and strongest, the best able both to 

 withstand the sea, and to stop the streams from flowing directly into 

 the sea : (2) that the very irregular shape and cliflfless character of 

 the shore of " the Fleet " are not such as one would expect to be 

 caused by the action of the sea along such a coast, whilst they are 

 just what should be produced by the action of streams : and (3) 

 that the Channel ends where the streams end. Westward of Abbots- 

 bury, where there are no streams, the beach is not separated from 

 the land ; eastward of Abbotsbury, where there are streams, the 

 beach is separated from the land. 



Whether there may have been a slight rising or sinking of the 

 land during the formation of the beach, would we think make little 

 difference, on the theory which we have brought forward. Whilst 

 we are far from asserting dogmatically that the Chesil Bank must 

 have been formed in the way described, yet we think that our theory, 

 or explanation, involves less supposition, and tallies more with 

 observed facts, than any other does, and that, therefore, it should be 

 accepted until replaced by a better, or disproved. 



Lastly, we wish to draw attention to the confirmation given to the 

 theory of Subaerial Denudation by our explanation of the origin of 

 the Chesil Bank, It was not until we were convinced of the truth 

 of the former that we saw our way to the latter; but when we 

 began to see how great has been the share of rain and rivers in 

 wearing away the land, and in cutting out hills and valleys, then we 

 ■were enabled, by the new light thus gained, to explain the origin of 

 a very uncommon phenomenon, which before we could not under- 

 stand or account for. What had previously been a mystery, and 

 looked like a freak of nature, became clearly intelligible, and was 

 seen to be the natural result of ordinary causes and existing agencies, 



Postcript. — In the discussion of this paper, Mr. J. Evans, F.E.S,, 

 " suggested that tidal action may have assisted materially in the 

 formation and widening of the Fleet." This we are far from 

 denying, although we omitted to notice in our paper the assistance 

 that may have been given by that action when it was enabled to 

 come into play. 



II, — On a Eaised Beach at Poktland Bill, Dorset, 



By W. Whitaker, B.A. (Lond.), F.G.S., of the Geological Survey of England. 



[PLATE XIV.] 



[A paper read before the Geological Society of London, May, 26, 1869.] 



IN 1850, Mr, H. W, Bristow recorded, on sheet 17 of the Geo- 

 logical Survey Map, the existence of "conglomerate" and 

 "recent stone" at Portland BiU. — (See Plate XIV. herewith.) 



