82 HISTORY OF THE EUROPEAN FAUNA. 



rule these stony clays thicken out as they are traced 

 from the high-lying tracts to the low grounds; and 

 especially near the mountains the rock-surfaces are 

 often polished and striated. " For many years it was 

 believed," continues Professor Geikie (p. 432), "that 

 all those superficial deposits were of iceberg origin. 

 The low grounds of Northern Europe were supposed 

 to have been submerged at a time when numerous 

 icebergs, detached from glaciers in Scandinavia and 

 Finland, sailed across the drowned countries, dropping 

 rock-rubbish on the way. Such was thought to have 

 been the origin of the erratics, stony clay, and other 

 superficial accumulations, and hence they came to be 

 known as the 'great northern drift formation."' " But," 

 he adds (p. 433), " when the phenomena came to 

 be studied in greater detail and over a wider area, 

 this explanation did not prove satisfactory. The 

 facts described in the preceding paragraphs the 

 occurrence of striated surfaces and roches mou- 

 tonnees, the disturbed appearances associated with 

 the till, and the not infrequent presence of giants' 

 kettles convinced geologists that all the vast 

 regions over which boulder-clay is distributed were 

 formerly occupied by the 'inland ice' of Scan- 

 dinavia." 



I think Professor Geikie over-estimates the value of 

 the evidences which appear to be in favour of his 

 theory. His treatise on the Ice Age leaves one 

 under the impression that the older view of the 

 marine origin of the boulder-clay is not only 



