74 31 R. F. DEBEXHAAI OX A XEW [vol. lxXV, 



shelly drifts of the Yorkshire coast it was evident that the material 

 of the sea-floor had in some cases been detached and transported in 

 strips and slabs, and the speaker had surmised the possibility of 

 ' anchor-ice ' as an agent, but had been unable to find evidence that 

 anchor-ice was formed in sea-water. The idea that a floating 

 glacier might receive continuous additions from below by the 

 freezing of the sea-water at considerable depths was new to him, as 

 he had been accustomed to suppose that the limit of downward 

 freezing under such conditions was soon reached. But, if the Author 

 was right in this respect, his theory offered a simple explanation 

 of the known facts. 



Prof. P. F. Kexdall said that glacial geologists would be 

 thankful to the Author for furnishing their armoury with a new 

 weapon. It was over forty years since the suggestion was made that 

 the occurrence of marine shells in glacial deposits could be explained 

 without recourse to a marine submergence. Three ways had been 

 indicated by which remains of marine organisms could be uplifted 

 by ice, and the Author had added a fourth. Garwood & Gregory 

 had found in Spitsbergen that the Ivory Glacier, in passing over an 

 upraised sea-floor, had incorporated in its lower layers shells and 

 other objects which, farther down the valley, come out on the surface 

 of the glacier at an altitude of probably 200 feet or more above 

 their place of origin. These writers attributed this to the lessened 

 mobility of the debris-laden basal layers of the ice. which would 

 ■offer resistance to the flow, and cause the development of a shear 

 that would bring the shells out on the surface of the glacier. 



The case of the Sefstrom Glacier, described by the President in 

 •a paper to the Yorkshire Geological Society, seemed to the speaker 

 to indicate the up thrust of subaqueous moraine by the nose of 

 the glacier. 



A third method of uplift mentioned by the President was by 

 the formation of anchor-ice. This, the speaker understood, was a 

 common occurrence in the Baltic, and fishermen, when far from 

 land, on the approach of winter watched carefully for the ap- 

 pearance of cakes of ice rising from the bottom to give them 

 warning of the imminence of a general freezing of the sea. Some- 

 times the warning came too late, and the boats were frozen in, and 

 had to remain until liberated by the spring thaw. 



The Author's interesting communication indicated yet another 

 way in which uplift might be effected. 



It is not clear how much of the shelly drift of the Xorth of 

 England can be accounted for by each of these explanations. In the 

 Irish-Sea basin, where shells are found up to altitudes of 1200 

 and 1-100 feet, it is significant that, as K. D. Darbishire pointed out, 

 the same suite of shells is found at the highest elevations as in the 

 low grounds ; moreover, the fauna is essentially a shallow-water 

 ■one, and the grouping characteristic of 200 fathoms is nowhere to 

 be found. Again, the shells are of various ages, many of them of 

 Pliocene types, and they often bear striations due to ice-action. 

 A few small patches like those found by the speaker in the Drift 



