124 Proceedings of the Royal Physical Society. 



rounded pebbles and stones, the larger of which appear at the 

 top and back of the mound, and the smaller lie in front, 

 towards the sea ; and the south-east end of the bank has larger 

 stones in it than the north-west end, where sand even exists 

 superficially. The base of the bank is conjectured to have a 

 layer of sand, resulting from the dehris of the trituration of 

 the pebbles above, and lying on a stratum of mud or clay, 

 which may also be sounded in the bottoms of Lyme Bay, 

 a considerable distance out. The bigger base, or larger end, 

 rests on the north end of the Isle of Portland at Chessil 

 Town, thence it stretches across the sea to the ferry at Wyke, 

 dividing Lyme Bay from Portland Bay, and afterwards courses 

 along the sea-coast. The sea face of the land inside it is low, 

 till the cliffs at Bradstock are reached, and between the land 

 and the bank lies a water lagoon, ranging from three-quarters 

 to one quarter mile broad, called the Fleet Water, emptying 

 itself into Portland Bay. 



The Chessil Bank has been amply described by numerous 

 writers for some time, and has formed the subject of long 

 controversies regarding its formation and constitution, which 

 are not yet satisfactorily concluded. Amongst them may be 

 mentioned the paper of Sir J. Coode, contributed to the Proceed- 

 ings of the Institute of Civil Engineers (vol. xii.. May 1853), 

 as the most valuable; and the debate on the question that fol- 

 lowed in the meeting of the Society is extremely interesting, 

 supported as it was by eminent scientific and professional men. 

 Next follows Professor Prestwich's communication to the Insti- 

 tute of Civil Engineers, and the report of the discussion there- 

 on at the meeting of February 2, 1875, recorded in the Proceed- 

 ings of the Institute of Civil Engineers (vol. xL, 1874-75). 

 Professor Prestwich has further discussed tlie Chessil Bank 

 in a paper in the Quarterly Journal of the Geological Society 

 (No. 121, February 1, 1875), and in the Geological Magazine 

 (vol. xii., 1875). Messrs Bristow and Whitaker liave also 

 written articles in the Geologiccd Magazine (vol. vi., 1869), 

 on the same. The chief points of discussion entered into 

 are those stated in the papers of Coode and Prestwich, 

 round whose rival arguments ranqe the rest of the writers 

 on either side of the controversy. 



