24 T. Codrington — On the Chesil Bank. 



the sea break, must be the determining cause of the line of the Chesil 

 Bank ; and Gough, in his additions to Camden (1789), mentions the 

 base of black clay left exposed when the sea breached the bank and 

 swept away the shingle. All the old accounts of the Chesil Bank 

 speak of its being broken through as if it were not an unfrequent 

 event, whereas it has not happened more than once, if at all, in the 

 present century. There is also reason to believe that its height is 

 now greater, and it has probably increased in size down to the 

 present time, its formation being the result of the present contour 

 of the coast line of the West Bay. 



The source of the materials of the bank is unquestionably the 

 coast between Sidmouth and Lyme Eegis, to the east of which are 

 Lias cliffs, which are being so rapidly destroyed by the action of the 

 sea, that it is easy to imagine that at no distant time the coast line at 

 that point advanced enough to stop the travel of the shingle. As 

 the removal of a few large blocks from the shore at Hengistbury 

 Head set the beach in motion to form the bank off Christchurch 

 Harbour, so the wasting of the Lias cliffs near Charmouth and Lyme 

 may be conceived to have removed the obstacle to the travelling of 

 a large accumulation of shingle, which, moving eastwards under the 

 action of the prevailing winds, was ultimately thrown up to form 

 the Chesil Bank. 



While the commonly received explanation of the formation of the 

 Chesil Bank is quite sufficient, the theory put forward by the 

 authors appears to have no facts to support it. Stress is laid on the 

 supposed circumstance that where there are no streams the beach is 

 not separated from the land, and that where there are streams it is 

 separated ; but this is not really the case. A stream flows down 

 from the west side of St. Catharine's Hill, and turns sharply to the 

 east on reaching the bank, on the inner side of which it flows for 

 about half a mile before reaching the head of the Fleet. It cannot 

 be supposed that the end of the Fleet has been excavated by this 

 stream after it has flowed through meadows for half a mile ; and the 

 next stream (that from Abbotsbury) enters the Fleet about a quarter 

 of a mile below its upper end. The hollow in which the Fleet lies 

 extends for more than half a mile beyond the latter, the bank rising 

 some twenty feet above the land inside, and sending out spurs which 

 were doubtless thrown up as " fulls " of beach at an early stage of 

 the growth of the bank. 



The Fleet is almost stagnant ; it is only at high spring tides that 

 any variation of level takes place at the upper end, so that tidal 

 action cannot have aided in its formation. The largest stream floAv- 

 ing into it is less than two miles long, and discharges, according to 

 Mr. Coode, but 80 cubic feet per minute. The tendency of this and 

 the other streams is to fill up the Fleet rather than to excavate it. 

 Deposits of mud line both sides, particularly at the mouths of the 

 streams, which are in fact small deltas of mud with no defined water- 

 courses. 



Lastly, if no real distinction can be drawn between the Chesil 

 Bank and other similar shingle banks, the theory falls to the ground, 



