298 THE ICE AGE IN CANADA. 



could not have existed. All the evidence, however, points 

 to subsidence and elevation owing to other and purely 

 terrestrial causes, and producing not produced by the 

 glaciers of the Pleistocene. 



It may be added that Upham accepts the recency of 

 the glacial period, and its causation by changes of ocean 

 currents, which of course would imply that its date 

 coincided in Europe and America, though not necessarily 

 or probably in the Southern Hemisphere. 



The very important series of papers by Prof. Prestwich 

 which have appeared within the last three years, and in 

 which that veteran and able student of the later geological 

 periods states his conclusions respecting the glacial and 

 Post-glacial deposits of the South of England, contain a 

 mine of information bearing on the glacial period in 

 America. The papers by Hicks, Hughes, Lapworth, Mel- 

 lard Eeade, Nicholson and others, respecting the high- 

 level gravels with marine shells in England and Wales, 

 have also elicited facts which tend to bring them into 

 harmony with those of America. The time was when the 

 boulder-clays and raised beaches of Eastern America were 

 explained by earthquake waves and glacier thrusts ; but 

 their vast extent and obviously submarine characters 

 have rendered such contentions untenable, and it may be 

 confidently predicted that this will be their fate in Great 

 Britain also. 



