SURFACE PHENOMENA. 185 



the surface-features now observed, which the author holds to be due to 

 subaerial action. W. T. 



Miller, Hugh. Glacial origin of Lake-Basins. Geol. Miig. dec. ii. 

 vol. iii. pp. 286, 287. 



Evidence of erosion is afforded when lakes lie among regular and 

 well-exposed strata, as, for instance, the Northumberland lakes and 

 Seraer water in Yorkshire, and lakes in the Cambrian sandstone in Ross 

 and Sutherland. From Suilven more than 200 lakes and tarns can be 

 counted. W. T. 



. Considerations bearing on Theories of the Formation of 



Rock-basins. Geol. Mag. dec. ii. vol. iii. pp. 451-455. 



If glaciers can excavate at all they can more easily enlarge a lake 



than they can start it. If lake-basins 2600 feet deep are due to 



depression, the influence of this ought to be seen in the neighbouring 



highlands. W. T. 



Milne, Prof. J. Ice and Ice-Work in Newfoundland. Geol. Mag. 

 dec. ii. vol. iii. pp. 303-308, 345-350, 403-410 ; 2 woodcuts. 



Discusses theoretical considerations on the flotation of icebergs ; 

 aspect of Newfoundland; ice-marks, W. Newfoundland; drift; coast- 

 ice ; ice-foot ; movements of coast-ice ; possibility of a sequence in 

 ice -action. Explains how glaciation and transport of boulders may 

 result from coast-ice. W. T. 



Murphy, J. J. The Glacial Climate and the Polar Ice-cap. Quart. 

 - Journ. Geol. Soc. vol. xxxii. pp. 400-406 ; and Froc. Belfast Nat. 

 Hist. Phil. Soc. 1875-76, pp. 18-33. 



Examines Croll's conclusion that, in the case of maximum eccentri- 

 city of the earth's orbit, the glaciated hemisphere is that which has its 

 winter in aphelion. Taking the maximum eccentricity at 0*069, the 

 heat received by the earth at the N. midsummer would be less than at 

 present in the ratio of 0-875 to 0-967, or nearly a tenth less. The 

 effect of this on terrestrial temperatures is estimated by comparison 

 with the supposed temperature of space ; and it results that the present 

 difference between summer and winter would be destroyed, in the N. 

 hemisphere, in all but the most extreme climates, and even that a 

 reversal of seasons will take place nearly to the Arctic Circle ; so that, 

 at the border of the frozen circumpolar area, the annual range is re- 

 duced to nothing. The result will be that then the ice and snow will 

 never melt, and a polar ice-cap wiU be formed. In the S. hemisphere 

 the great heat of the perihelion summer will rapidly melt the snow 

 that fell during the aphelion winter. To Croll's argument that in the 

 Antarctic regions, where the summer is in perihelion, there is now a 

 glacial climate, he replies that the present Antarctic climate is a mari- 

 time one, and hence its range of temperature is not great ; it would be 

 different if laud and sea were equally distributed in the two hemi- 

 spheres. F. D. 



