ioo REVIEWS 



indicated as representing successive lengthening of the periods of the ice 

 retreat, the slate present above the tillite representing the final retreat of 

 the ice, followed by subsidence and deposition. 



The age of the Squantum tillite is given as Permo-Carboniferous, 

 with a probability that because of the widespread Permian glaciation it 

 may be Permian. 



C. B. A. 



"Die Gletscher des Sarekgebirges und ihre Untersuchung." By 

 Axel Hamberg. Sveriges geologiska undersokning, Ser. Ca., 

 I, 4:0, No. 5. Pp. 26 (4010), pis. 4. 



The Sarekgebirge are the largest range in Sweden and contain more 

 than 100 glaciers. Increase of snowfall toward the west, lower tempera- 

 ture in the north, and elevation above the sea determines the location 

 of the larger and greater number of glaciers in the high, northwest part 

 of the range. Winds are very strong, so topography has a very important 

 influence in the locations of snow-fields. At high altitudes, however, the 

 work of hoarfrost (Rauhfrost) to some extent counterbalances the effect 

 of the wind. Two types of glaciers are distinguished: (1) valley glaciers, 

 mostly in young cirquelike valleys at the edge of the upland, ranging in 

 length from a few hundred meters to 5 or 6 km.; and (2) plateau 

 glaciers which form on the broadly undulating flat tops of some of the 

 mountains. The latter are not like the convex surface I nlandeistypus 

 of Norway. Cliff glaciers are present, also, in very subordinant number. 



Experiments were made to determine the yearly snow accumulation 

 at various points on some of the larger ice-fields. This was done 

 by means of marked standards and showed: 



At 1,200 m. elevation o accumulation = snow line 



1,340 m. elevation 1.29 m. accumulation per year 



1 ,440 m. elevation 2.16 m. accumulation per year 



1,500 m. elevation 2.43 m. accumulation per year 



Observations on the rate of melting at the surface of the glaciers were 

 undertaken by means of bored holes, the bottoms of which were specially 

 marked. This showed a very rapid decrease of melting with increased 

 distance from the lower edge of the ice. 



Dist. from glacier end (m.) 150 350 1,000 2,000 



Elev. above sea (m.) 970 1,000 1,100 1,200 



Melting in 1 year (cm.) 330 244 90 4 



