230 PK0CEBDING8 OF THE GEOLOGICAL SOCIETY. [Feb. 8, 



that the edges, or one of the edges, of an Inferior-Oolite island may 

 be coincident in position with a Great-Oolite island above. 



There remains the question of the meaning of finding on opposite 

 sides of a valley zones containing assemblages of similar organic 

 remains. The author believed that this in no way bears on the 

 question of the original continuity or otherwise of the two sides. 

 If there are beneath the sea two spots (a and h) near together, 

 having exactly similar conditions for life, the assemblage of forms 

 at both places might be the same, whether a and h are separated by 

 a channel or not. 



In conclusion, the author remarked that, though he had arrived 

 at this idea inductively, yet he believed it would be fair to start 

 with the statement that coral islands when covered up would retain 

 their contour ; and it would rest with those who insist on continuous 

 limestone-beds in all cases to show why the islands with deep 

 channels between them must have been broken up and spread out as 

 a continuous sheet before the sedimentary deposit was accumulated 

 on them. He also expressed his belief that the present view com- 

 monly held affords a correct explanation of the phenomena of Oolite 

 valleys in many cases. 



Discussioisr. 



Prof. MoKKis did not consider that the author's views as to the 

 oolitic masses round Bath being originally isolated coral banks with 

 clay beds, although suggestive, were quite satisfactory. He pointed 

 out that the strata on each side the valleys were similar in structure, 

 mineral character, and fossil contents, and were once continuous ; and 

 the present intervening deep valleys were rather due to the movements 

 which the area had undergone in producing lines of weak resistance, 

 subsequently assisted by the erosive action of percolating and running 

 water, both in excavating and undermining the harder rocks, so as 

 to cause them to bend towards the hill-sides, or fall in larger or 

 smaller masses on their slopes. 



Mr. Seelet thought that Mr. Mitchell was justified in applying 

 considerations drawn from the formation of coral islands to the 

 elucidation of the phenomena under discussion. He maintained 

 that shallow- water limestones must always occur in isolated masses 

 with intervening masses of clay, and that the clay might be washed 

 out, leaving the limestone as hills. 



Mr. Whitakek held that when like beds cropped out on the tops 

 or flanks of opposing bills it was a logical inference that the said 

 beds had once spread across the space between, and that there was no 

 need to call in the agency of supposed coral islands to explain the 

 occurrence of isolated masses of limestone, which were perfectly 

 accounted for by denudation, an agency that involved no supposition, 

 and was quite equal to the work. 



Mr. Etheridge remarked that the moUusca of the outliers of the 

 Oolites in the Severn Valley were constant in beds at the same rela- 

 tive level. He also referred to the sliding of the oolitic strata of 

 the Cotteswolds upon the subjacent clays as accounting for the dip 



