150 Scientific Intelligence. 



glacier theory, based on the transportation of bowlders in differ- 

 ent or opposite directions over the same area, as if they had been 

 borne by icebergs driven about by changing winds, is triumph- 

 antly answered. In the case of a number of localities in France, 

 Germany, and Britain, it is shown that the comparatively local 

 glaciers of an incipient or waning glacial epoch would necessa- 

 rily move in a different — sometimes even in an opposite — direc- 

 tion from that of the portions of the huge confluent glaciers by 

 which the same regions were covered in the culmination of a gla- 

 cial epoch. The phenomena in question are thus shown to be an 

 inevitable consequence of the glacier theory. 



In this, as in his former works, Professor Geikie advocates the 

 doctrine of a plurality of glacial epochs. The following is the 

 series of Glacial Epochs, according to his latest views:* 



"1. Epoch of Earliest Baltic Glacier. — Lowest bowlder-clay 

 of southern Sweden ; lowest bowlder-clay of Baltic provinces of 

 Prussia; horizon of the Weybourn Crag. 



2. Epoch of Greatest Mer de Glace. — Lower bowlder-clays of 

 middle and southern Germany, central Russia, British Islands; 

 second bowlder-clay of Baltic provinces of Prussia. 



3. Epoch of Lesser Mer de Glace. — Upper bowlder-clay of 

 western and middle Germany, Poland, and west central Russia ; 

 upper bowlder-clay of Britain ; third bowlder-clay of Baltic prov- 

 inces of Prussia. 



4. Epoch of Last Great Baltic Glacier. — Upper bowlder-clay 

 and terminal moraines of Baltic coast-lands; district and valley 

 moraines of Highlands and Uplands of British Islands. 



5. Epoch of Small Local Glaciers. — Valley moraines in moun- 

 tainous regions of Britain, etc." 



A fuller presentation of the evidence of the views set forth in 

 the above table is promised in the forthcoming new edition of 

 " The Great Ice Age." 



The problem of the Loess is the subject of valuable discussion. f 

 The eolian theory is rejected, largely on the ground that the 

 prevalence of an excessively dry climate is inconceivable, since 

 "the loess is intimately associated with accumulations, the gla- 

 cial and fluvio-glacial origin of which cannot be doubted. "J The 

 loess is considered, in the main, " an inundation-mud deposited 

 in temporary lakes and over flooded areas during the summer 

 meltings of the snow- and ice-fields." Darwin's suggestion is 

 approved, that many valleys were choked with snow, whereby 

 the flooded rivers were often compelled to flow in temporary 

 channels at levels far above the bottoms of the valleys§ — a sug- 

 gestion which finds confirmation in some remarkable phenomena 

 observed in Alaska. The loess of north Germany is held to have 

 been formed in a lake enclosed between the front of the ice-sheet 

 and the foot-hills of the mountains of central Germany. || 



* Page 325. f Pages 1 76, 236. % Page 177. 



§ Page 180. || Page 182. 



