Geology and Natural History. 383 



in this a valuable reference book with references to the more val- 

 uable original papers. No doubt it will be chiefly useful, how- 

 ever, to scientists of other countries, who will find in it not only 

 a summary, but a key to the voluminous literature on the geology 

 of the United States. They will be aided in this by the clear style 

 in which the subject-matter is set forth. j. b. 



5. Untersuchungen uber die Gezeiieu der festen, Erde und die 

 hypothetische Magmaschicht ; von Dr. VVilhelm Schwkydae. 

 Veroffentlichung des k. k. Preusz. geodiit. Institutes. Neue Folge 

 No. 54. Pp. 58. Leipzig, 1912 (B. G. Teubner).— This is a math- 

 ematical investigation of the theory of the horizontal pendulum 

 and its response to tidal strains in the earth. The calculations are 

 designed to test the presence or absence of a viscous zone between 

 an elastic crust and elastic interior. It is concluded that even a 

 magma bed with a viscosity as high as that of sealingwax at 

 house-temperatures and a thickness of but 100 kilometers cannot 

 be present. The assumption in best agreement with observations 

 is that of the presence of a layer about 600 kilometers thick, 

 slightly ductile (coefficient 10 13 to lo' 4 ), existing beneath an outer 

 crust 120 kilometers thick. j. b. 



6. Variations of Glaciers in 1911. — The annual report of 

 the " Commission Internationale des Glaciers," published in the 

 Zeitschrift fur Gletscherkunde, Vol. VII, pp. 37-47, 1912, con- 

 tains less material than usual, owing to the absence of measure- 

 ments recorded in North America, Asia, the French Alps, and 

 Russia. For the Swiss Alps, Forel and Muret give a comparison 

 of the year 1910 with the thirteen years immediately preceding, 

 which shows that decrease in length of glaciers continues to be 

 normal. The glaciers of the eastern Alps likewise indicate that 

 decrease in length and volume has not yet reached its maximum; 

 even the three glaciers of the Wildspitze, which advanced during 

 the period 1904-10, retreated in 1911. Apparently abnormal 

 seasons rather than a general climatic change are responsible for 

 the forward movement or stationary condition of a group of small 

 glaciers in this region. Of 38 glaciers observed in the Norwegian 

 highlands, only two show increases; the others have decreased 

 from 2 to 34 meters. In reporting on these ice masses, Oyen calls 

 attention to the interesting fact that portions of the same glacier 

 move with different rates and in different directions. For the 

 western and northern coast of Norway 12 out of 28 glaciers show 

 increase, the maximum of 50 meters being in the Buarbrae 

 valley; while the maximum decrease, Lodalsbrae, amounted to 19 

 meters. The Frostis glaciers and those on the Okstind mountains, 

 8 in number, indicate increase. h. e. g. 



7. New Zealand Department of Mines, Geological Survey 

 Branch, P. G. Morgan, Director. Bulletin No. 12 {New Series) : 

 The Geology of the Dun Mountain Subdivision, Nelson; by 

 James Mackintosh Bell, Edward DeCourcy Clarke, and 

 Patrick Marshall. Pp. 71 ; pis. I-IX ; plans, 4 ; maps, 4 ; Geo- 

 logical sections, 3 ; Wellington, 1911. — The survey of the Dun 



Am. Jour. Sci.— Fourth Series, Vol. XXXV, No. 207.— March, 1913. 

 23 



