Yol. 54.] ON THE GLACIAL GEOLOGY OF SPITSBERGEN. 225 



Plate XVII. 



Fig. 1. Terminal fronts of Booming and Baldbead Glaciers. 



2. Ice-talus formed from advancing upper layers, Booming Glacier. 



Plate XVIII. 



Fig. 1 . View showing the raised edge of Booming Glacier. 

 2. Booming Glacier, looking up. 



Plate XIX. 



Fig.l. Upper portion of Booming Glacier, showing the centre sagging away" 

 from the side of the yalley. 

 2. View of Starashchin Eidge. 



Discussion. 



Sir Maetin Conway called attention to the fact that the whole of 

 the oval terminal dome of the Ivory Glacier — 3 miles wide, 2 miles 

 long, and about 400 feet thick — had been formed by the advance of 

 the glacier from the neighbouring side-valley to the north since 

 Yon Heuglin's visit to Agardh Bay in 1870. The moraine-hills 

 (220 feet above the level of the raised beach below) had therefore 

 all been formed within that short interval. Referring to the 

 advance of some of the Spitsbergen glaciers and the retreat of 

 others, he pointed out that the glaciers which terminate with an 

 ice-cliff in shallow bays, if they do not advance over the moraines 

 deposited by them in the water, must cut themselves off from the 

 water by a ring of terminal moraines. Instances of glaciers thus 

 cut off, and of others thus advancing into the sea, were observed 

 by the 1897 Expedition. 



Prof. BoNNEY enquired whether Dr. Gregory had been able to 

 establish any relation between the height to which a glacier had 

 lifted material and that from which it had descended. He doubted 

 whether much striation of pebbles would go on in the ice, but said 

 that in Switzerland the number of striated pebbles increased as the 

 moraine became more distant from the present end of the glacier. 

 He also asked whether the beach-material was found to rise from 

 the north towards the south, that is, in the direction of movement 

 of the glacier. He thought the paper a most important one. 



The Rev. Edwin Hill said that now for the first time we are given 

 an intelligible theory of how moving ice may pick up materials and 

 raise them high above its floor. The advance as described seemed 

 analogous to that of a wave breaking on a beach, or a ' bore ' 

 advancing up a river. The uplifting action required a good deal of 

 thought to attain a clear conception of its cause. The talus would 

 doubtless be incorporated in the advancing mass and, he thought, 

 might not much impede it, but the theory seemed complete, and 

 independent of this. Such ice as that described neither ploughed 

 nor eroded, contrary to common views, nor did he hear anything 

 of intercrossing streams. A medial hollow might follow from sub- 

 glacial melting, but what was the cause of advance if the rear were 

 lower than the front ? He had never listened with more interest 

 to any paper. 



