Geological Society of London, 329 



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Geological Society of London. — I. — May 8, 1872. — Joseph 

 Prestwich, Esq., F.E.S., in the Chair. — The following communica- 

 tions were read :— 1. " Notes on Atolls or Lagoon-islands." By 

 S. J. Whitnell, Esq. Communicated by Prof. Maskelyne, F.E.S., 

 F.G.S. 



The author commenced by indicating certain facts which lead him 

 to think that the areas of atolls are not at present sinking, and re- 

 ferred to one instance (that of Funafuti or Ellice Island) in which 

 he thought there were signs of a slight upward movement. He 

 noticed the occurrence of a furrowed appearance, or a series of ridges 

 or mounds, in some islands, each of which he regarded as produced 

 by a single gale. He also described a freshwater lagoon, about three 

 miles in diameter, as occurring in the island of Quiros. 



Discussion.— Mr. Thorpe was acquainted with the atolls around the coast of Ceylon, 

 and thought that the local traditions, untrustworthy as such sources usually were, 

 might afford some evidence as to the date of their origin. The tradition in Ceylon 

 was that the Maldive and Laccadive Islands had within the meraoxy of man heen 

 connected with Ceylon, If this were so, the evidence was in favour of the area heing 

 one of subsidence. 



Mr. D. Forbes, when in 18-59 he spent some months in the Pacific, had been re- 

 quested by Mr. Darwin to examine into the evidence as to the origin of these atolls 

 by elevation, and had found that the asserted cases of the existence of masses of 

 coral at a considerable elevation above the sea merely arose from blocks having been 

 transported inland by the natives. Though, however, there was no evidence of eleva- 

 tion, it was still possible that such had in certain cases taken place, as there were still 

 active volcanoes in this region. The freshwater lakes he attributed to the drainage of 

 the islands. 



2. " On the Glacial Phenomena of the Yorkshire Uplands." By 

 J. E. Dakyns, Esq. Communicated by Professor Eamsay, F.E.S., 

 V.P.G.S. 



The author stated that in Derbyshire and Yorkshire, south of the 

 Aire, there is no glacial drift on the eastern slope of the Pennine 

 chain, except where it is broken through by the valleys of the Wye 

 and of the Aire and Calder. The basin of the Aire and the country 

 northward are thickly covered with drift, which contains no rocks 

 foreign to the basin, and thus points to formation by local action. 

 The author ascribed this to the glaciation of the country in part by 

 glaciers, and in part by a general ice-sheet. Evidence of the latter 

 he finds in the fact that drift occurs only on one side of the valleys, 

 namely, on the lee-side of the hills with respect to the source of the 

 drift materials. Traces of the action of glaciers are, the great amount 

 of scratched and rounded pebbles in the mounds of drift, which in- 

 creases in proportion to the distance from their source ; the presence 

 of great piles of drift at the junctions of valleys, as if by the shedding 

 of the lateral moraines of two glaciers ; and the existence of mounds 

 of pebbles and of an alluvial deposit wherever a rock-basin crosses a 

 valley. The Kames or Eskers, which are frequent in the valleys, he 

 ascribed to the deposition of moraines in the sea instead of on land. 



DiBcussiON. — Prof. Eamsay agreed with the author as to the existence of these 



