Analytical Abstracts of Current 

 Literature. 



Verlauf Der Gronland- Expedition der Gesellschaft fur Erdkunde. Dr. 



Erich von Drygalski. Verhandlungen der Gesellschaft fur 



Erdkunde zu Berlin, 1893, Nos. 8 u. 9. 

 This article is mainly a sort of itinerary with little geological detail. The 

 glacial investigations referred to were carried on chiefly on the mainland east 

 of Disco. The author emphasizes the fact that the surface of the inland sea near 

 its edge is much dissected by valleys cut by surface streams, and that there 

 are upon the ice many pools and little lakes due to melting of the ice beneath 

 patches of dust. In the warm season there are many lakes about the border 

 of the ice held in on one side by the ice. With the first sharp cold the ice 

 cracks so as to let the water escape. The author's microscopic study failed 

 to discover any essential difference in structure between glacial ice and lake 

 ice, though the fjord ice was somewhat unlike both. Dr. von Drygalski thinks 

 that the contained water alone gives to glacier ice the power of movement, 

 and that, therefore, there is no motion without a melting temperature. It is 

 thought that the melting temperature maintains itself at the bottom of the 

 ice by virtue of the transfer of heat from the upper surface during the melt- 

 ing season. Since the upper part of the ice must be below the melting point 

 during a large part of the year, it is thought that movement depends more 

 on the lower than on the upper layers. The author is doubtful of the truth- 

 fulness of the comparison between ice streams and rivers. The temperature 

 of the mass is thought to fluctuate about the freezing point, and its work and 

 motion are thought to depend upon the change from a solid to a fluid condi- 

 tion, and vice versa. 



R. D. S. 



The Geology of Angel Island. F. Leslie Ransome. (Bulletin Geo- 

 logical Department of University of California, Vol. 1, No. 7.) 

 Angel Island is about a square mile in extent, and lies in San Francisco 

 Bay, three and one half miles northeast of San Francisco. The larger por- 

 tion of the island is occupied by the San Francisco sandstone, which contains an 

 abundance of plagioclase and other non-quartzose fragments. Interbedded 

 with the sandstone are numerous masses of jaspery rock elsewhere denom- 

 inated "bedded jaspers," but the discovery of an abundance of remains of 



863 



