1882.] 37 [Davis. 



ing great areas of glaciated rock, with plentiful boulder-clay 

 resting directly on its polished surface ; the only exceptions to 

 this are in south-eastern Sweden, farther from the centre of glacial 

 motion, where there seems to be a nonglacial deposit beneath the 

 till at some points. 



Tli. Kjerulf describes the striated rocks and erratics in detail, but does 

 not mention any loose subglacial detritus. (Geologie des sudlichen Norweg- 

 ens (trans, by Gurlt); Bonn, 1880.) 



Erdmann speaks of a glacial erosion in Sweden sufficient to destroy or 

 greatly to decrease certain areas of stratified rocks now known only by 

 their fragments in the drift or limited to small spaces ; he describes the till 

 (krossten grus, gravier anguleux) as occurring everywhere without deposits 

 between it and the striated and polished rocks below, excepting in some 

 low grounds near the coast, where an intermediate " argile " has been 

 found. (Formations quaternaires de la Suede, Stockholm, 1868, 24, 25.) 



O. Torell states that as a rule in Scandinavia one finds scratched rock 

 surfaces immediately below the till (ground moraine), but east and south of 

 the Baltic, loose, stratified deposits occur between the till and the pregla- 

 cial strata. He considers these stratified deposits to have been washed off 

 from the advancing ice, as Favre explained the " alluvion ancienne " of 

 Switzerland, and he implies that the rocks below are not striated. (On the 

 causes of the Glacial Phenomena in the N. E. portion of North America, 

 Stockholm, Akad. Handl. Bihang. v, 1877, and Amer. Journ. Sci. xin, 

 1877, 76.) 



Crossing the Baltic there is a complete change. The quater- 

 nary plain of North Germany seldom shows any bed-rock, but 

 consists of a complicated set of unstratified and stratified drifts, 

 the effect of land-ice and running water repeated in several 

 alternations, and as a rule showing more the effect of depo- 

 sition than of local erosion. There are however certain examples, 

 especially in the lower beds of till, showing very considerable 

 disturbance in the Cretaceous and Tertiary rocks, such as might 

 be produced by the long continued pressure against rock escarp- 

 ments (B. 3.) ; but the same sheet of lower till, if rightly 

 identified, is often found resting on loose, stratified preglacial 

 gravels ; similar interglacial beds occur between the several 

 deposits of boulder-clay, with their bedding as a rule but little 

 disturbed. 



A. Penck supposes three successive advances of a Scandinavian ice-sheet 

 over North Germany, each advance adding a deposit of till, and burying 



