REVIEWS 101 



Measurements on a number of the larger glaciers of the rate of move- 

 ment were made. These showed the differential movement in various 

 parts of the individual glaciers and indicated a much greater speed 

 of movement in the summer. Not any variation of importance has 

 been observed in the position of the lower end of the larger glaciers in 



recent years. 



R. C. M. 



"Die Geomorphologie und Quartargeologie des Sarekgebirges." 

 By Axel Hamberg. Geol. foren. forhandl., Bd. 32, Heft. 4, 

 April, 1910. Pp. 25, map 1. 

 The Sarekgebirge (north Sweden) are made up of the following 



rocks : 



4. Amphibolite (1,000-1,200 m.) 



3. Syenite (350 m.) 



2. Silurian beds (150 m.) 



1. Basement complex 



The topography shows a striking dependence on the structural 

 relations and resistance of the rocks. As an example is cited the devel- 

 opment of numerous falls where the easily eroded Silurian shales have 

 been weathered from beneath the resistant syenite. The mountain 

 massifs are mostly flat-topped, possibly indicating remnants of an old 

 erosion surface. Large deep valleys have been cut in the amphibolite 

 but not far into the syenite. This is doubtless due to the superior 

 resistance of the latter, not to any interruption of a former drainage 

 cycle. 



The Sarekgebirge were almost certainly a center of ice dispersion 

 in the early Pleistocene. The presence of erratics from some distance 

 to the southeast indicates that the center of ice movement later changed 

 in this direction. In the retreat of the ice there was apparently a time 

 when the ice from the southeast was no longer able to move up the slope 

 of the mountains, and lakes were formed between the valley walls and 

 the edge of the ice. Shore-line phenomena, especially where the valley 

 walls are less steep, mark the levels of these lakes, but because the outlet 

 over the ice was continually and gradually lowered, the level of the lakes 

 was inconstant, and instead of a few sharply defined beaches there are 

 a large number of indistinct shore lines. Ice blocks left at certain places 

 in the valleys seem to have determined in part the courses of certain 



