324 D. Bell — The Great Ice Age and Submergence. 



makes the less not only probable, but in many cases perfectly 

 certain. 



But perhaps it is meant that there is something " peculiar " in the 

 Clava deposit itself, which forbids this explanation being applied to 

 it. Its " extent " is referred to, and its "maintaining a horizontal 

 position, and exhibiting no trace of deformation or disturbance." 

 These are points, however, on which the evidence, as given in the 

 Keport, does not appear to be at all conclusive ; on one or two of 

 them, indeed, it inclines quite the other way.' We believe it can be 

 rfiown, keeping to what is proved in the Eeport, that whatever 

 difficulties the features of the deposit present on the one hand 

 to the ice-transport theory they present still greater difficulties on 

 the other to the theory of a marine deposit in situ. But to this 

 we shall return. 



Meantime we may note, in passing, that Dr. Geikie unduly 

 heightens the case against the ice-transport theory by representing 

 its purport to be that the shelly clay was " pushed or dragged 

 forward under the ice-sheet" for so many miles. The minority, how- 

 ever, did not express it in these terms, nor did they define the 

 precise mode in any terms ; and they may very pi-operly object to 

 Dr. Geikie doing it for them. Certainly, by his own account, this 

 mode does not "necessarily follow." We are elsewhere told of 

 stones or boulders which, " once imbedded in the ice," may have 

 been carried for " a hundred miles without suffering abrasion.'^ It 

 seems hard on the shelly deposits that they could not in some 

 instances (as frozen masses, perhaps) be transported in the same 

 gentle fashion, for ten or twelve miles ! 



But Dr. Geikie proceeds to discuss the case on more general 

 grounds, into which we must now shortly follow him. 



11. 



The first part of the more general ground which Dr. Geikie 

 takes up in arguing for a submergence during Glacial times of 

 over 500 feet, has reference to the non-fossiliferous character of the 

 " Upper Boulder-clay." The statement that *' had such a degree of 

 submergence ever taken place prior to the advance of a general 

 ice-sheet, we should surely find the ground-moraine of that ice- 

 sheet more or less abundantly charged with relics of marine life," 

 he meets by saying, " this does not necessarily follow." ^ 



The author has evidently got some new light on the subject 

 since the date of his previous edition. He then alluded to this 

 absence of marine organisms in the Upper Boulder-clay as an almost 

 insuperable difficulty against the theory of a submergence. "Why," 

 he wrote, " we may ask, does not the Upper Boulder-clay of the 

 Central Lowlands (a great proportion of which must have been 

 submerged before the last ice-sheet overflowed Scotland) contain 

 broken shells, and afford other indications of the latest confluent 

 glaciers having usurped the bed of the sea? That is a. very hard 

 question to answer, and I fear we must wait some time yet for an . 

 1 Brit. Assoc. Eeport, 1893. 2 p_ 204. ^ p. 141. 



