﻿206 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 26, 



In the first place, we have frequent notices of large surfaces covered 

 to the depth of two feet by angular fragments which the frost had 

 detached from the rock (limestone) lying beneath, — of innumerable 

 blocks of limestone constantly detached from an adjoining precipice 

 and rolling down slopes, — of ground covered for the space of a mile 

 with small pieces of slaty limestone, the cliffs in many places resem- 

 bling ruined battlements, from which fragments were continually 

 falling. We have notices also of pillars of rock rising like stacks of 

 chimneys and surrounded with masses of their debris. These last 

 may be compared to the peaks of bare rock, surrounded by great 

 heaps of their own angular blocks, so common on the summits of the 

 Welsh mountains. 



Secondly, on the melting of the snow, during the short arctic sum- 

 mer, the ravines are filled with furious torrents which hurry much 

 detritus into the sea. Where the land is high, the greater accumu- 

 lation of snow furnishes a constant supply of water during the whole 

 summer ; but where it is low, it soon becomes free from snow, the 

 ravines entirely dry, and the whole face of the ground parched and 

 cracked, as if there had been no moisture on it for a long time. 



The detritus thus hurled into the sea produces points of land at 

 the mouths of the ravines. This is so invariable a fact, that Sir E. 

 Parry declares that " in case of danger from the sudden closing of the 

 ice, a ship may always be sure of meeting with one of these points, 

 which are too small to be seen at a distance or delineated on the chart, 

 by steering for one of the ravines, the latter being distinguishable 

 several miles from the land." 



Lastly, it was observed that in the beginning of the summer, the 

 snow, when partially melted, freezes again into a thin cake of ice. In 

 some seasons and in some situations, this appears to be the extreme 

 limit of the thawing process ; certain cliffs which, when visited at 

 one season, were clear of snow, were found at the close of another 

 colder summer covered by a layer of blue transparent ice, the result 

 of the partial thawing of the snow, arrested by the frost. 



Such conditions would be particularly favourable to the enveloping 

 of detritus in ice, to its sliding down slopes thus enveloped, and to its 

 final transport to the sea. It might slide down slopes, and be floated 

 over level surfaces. It might make the journey to the coast, by suc- 

 cessive stages, during several seasons ; and at each halt scratches 

 previously received would, upon the land, be safe from that oblitera- 

 tion, which it is objected must take place upon the sea-shore. At 

 each stage of its journey it might present a different surface to the 

 polishing and scratching action ; and at length, still imbedded in ice, 

 it might reach one of those violent and transient torrents, by which 

 it might be floated out to sea and dropped, on the melting of the ice, 

 into the mud in the condition of the specimen exhibited at the Meet- 

 ing (see fig. 3). 



From these considerations, the accordance of the state and distri- 

 bution of the fragmentary matter in the Till of Norfolk and Wales 

 with the observed effects of marine and atmospheric action under an 

 arctic climate was inferred in the paper alluded to in a former com- 



