132 Notices of Memoirs — Singleness of the Ice Age. 



importance, their equivalence, all present difficulties. He finds 

 adjacent and probably equivalent fossiliferous beds ranked differently 

 by different authors ; a series will by one be designated Interglacial 

 which another calls no more than a local deposit of sand or claj'- 

 The latest researches in Quaternary geology have led to the following 

 conclusions : — For Sweden it has been shown that the Ice Age there 

 was single, unbroken by Interglacial periods. Examination of the 

 moraines south of the Baltic shows that these are no boundaries 

 of ice-extension, but only mark stages of retreat. The so-called 

 ' First Ice Age ' covered a narrower area than the ' Second or 

 Principal Glaciation ' ; the ' Third,' again, less than the Second. 

 Views on the importance of the ' Upper ' and ' Lower ' Boulder-clays 

 are more and more extending the domain of the Upper. The list 

 of the fossiliferous ' Interglacial beds ' is continually increasing. 



It must be remembered that while in the northern districts 

 removals of material will have predominated, accumulations will 

 have been the rule in the centre, fluvio-glacial formations in th& 

 southern border-region. Glaciers, and in like manner ice-floes and 

 ice-packs, will have produced plentiful disturbances of beds. 



Considering everything, the author is driven to the conclusion 

 that " for the southern area of glaciation as for the northern, the 

 whole Drift is to be treated as a single sequence, only broken by 

 oscillations" ; that "only one Ice Age has existed, instead of the 

 supposed three (or four) sandwiched in with Interglacial periods 

 of long duration. Consequently the facies accepted as intermorainic 

 must be ascribed only to somewhat larger oscillations of the ice-front, 

 not to periods wholly free from ice." 



He quotes Hoist's views on an elevation of Scandinavia, which 

 would increase its glaciers ; while the increase of ice would produce 

 depressions ; and discusses the probable sequence and consequences. 



Depressions would extend areas of submergence ; connection with 

 cold-water seas would bring deposits of Arctic forms ; with warmer 

 waters, temperate. On land, animals and plants would follow 

 advances and retreats of the ice-front. 



Discussing the records, he decides that " the fauna and flora 

 of the Quaternary period indicate a climate like the present, only 

 slightly warmer." But the mighty mass of ice affected climate, 

 lowering it over North Europe. The northern ice advanced, with 

 many oscillations, pushing forward especially into bays and valleys, 

 leaving intervening areas free of ice. Consequent alterations of 

 level would produce or remove submergences. Finally, the period 

 of retreat seems a time of somewhat greater warmth than the present, 

 and lasted considerably longer than the period of advance. 



One may say that the Ice Age to a certain extent worked its own 

 downfall — rise of Scandinavia and vast development of glaciers ;. 

 consequent depression ; access of warm currents and rise of 

 temperature ; commencement of melting. 



The same considerations are applicable to Great Britain, where 

 the marine deposits, in close relation to the Boulder-clay, play a yet 

 more important part. 



