6 4 o SCIENCE PROGRESS 



Geology and Ore Deposits of Copper Mountain and Kaasan 

 Peninsula, Alaska, by C. W. Wright ; and Bulletin 587, Geology 

 and Mineral Resources of the Kenai Peninsula, Alaska, by G.C. 

 Martin et alia). 



Glaciology. — Dr. Nils Olof Hoist, late of the Geological 

 Survey of Sweden, furnishes an excellent synopsis of the Ice 

 Age in England from a Continental point of view (Geol. Mag. 

 191 5 (6), 2, 424, 434, 504). 



The form of the ice in the frozen tundras of the north 

 coast of Alaska is discussed by E. de K. Leffingwell (Journ. 

 Geol. 191 5, 23, 635). In contradiction of the view that the 

 ice forms horizontal beds of considerable lateral extent, he 

 shows that it exists chiefly as a network of vertical wedges, 

 thinning downward, and surrounding isolated bodies of the 

 tundra formation. The latter is often much disturbed and 

 contorted in the neighbourhood of the ice ; and these obser- 

 vations may help to explain similar phenomena in Pleistocene 

 glacial deposits. 



The existence of two glacial stages in Alaska is demonstrated 

 by S. R. Capps (Journ. Geol. 191 5, 23, 748) by the discovery 

 in the White River basin of a 3,000 feet thick series of glacial 

 tills interstratified with outwash gravels, assorted sediments, 

 and a few lava-flows. This series can be proved to antedate 

 by a considerable period of time the last great ice expansion, 

 which was probably contemporaneous with the Wisconsin 

 continental glaciation. 



Petrology .—A. Scott has described the field relations and 

 petrography of the well-known Crawfordjohn (Lanarkshire) 

 essexite (Geol. Mag. 1915 (6), 2, 455). It is an elongated plug 

 or small boss which has no connection whatever (as formerly 

 thought) with the Tertiary north-west dykes, but must be 

 regarded as an outlying member of the Late Carboniferous 

 alkaline series of Scotland. Analyses of the essexite and of 

 its monchiquitic contact-rock are provided. 



Two of the differentiated nepheline-syenite laccoliths of 

 Ontario are described and discussed by W. A. Foye (Amer. 

 Journ. Sci. 1915,40, 413). He indicates the close association 

 of granite with these rocks, and believes that the nepheline- 

 syenite has arisen by the reaction of limestone with granite, 

 and that gravity has been the controlling factor in the arrange- 

 ment of the various types within the laccoliths. 



