174 



ISLAND LIFE. 



[part I. 



extensive collections of organic remains have been made of any 

 formation yet explored, and from nearly all its horizons, for at one 

 place or another in these three countries nearly every horizon 

 may be said to have yielded fossils of some kind. These fossils, 

 however, whether they be the remains of a flora such as that of 

 Sheppey, or of a vertebrate fauna containing the crocodile and 

 alligator, such as is yielded by beds indicative of terrestrial 

 conditions, or of a molluscan assemblage such as is present in 

 marine or fluvio-marine beds of the formation, are of unmis- 

 takably tropical or sub-tropical character throughout ; and no 

 trace whatever has appeared of the intercalation of a glacial 

 period, much less of successive intercalations indicative of more 

 than one period of 10,500 years' glaciation. Nor can it be urged 

 that the glacial epochs of the Eocene in England were intervals 

 of dry land, and so have left no evidence of their existence 

 behind them, because a large part of the continuous sequence 

 of Eocene deposits in this country consists of alternations of 

 fluviatile, fluvio-marine, and purely marine strata ; so that it 

 seems impossible that during the accumulation of the Eocene 

 formation in England a glacial period could have occurred 

 without its evidences being abundantly apparent. The Oligocene 

 of Northern Germany and Belgium, and the Miocene of those 

 countries and of France, have also afforded a rich molluscan 

 fauna, which, like that of the Eocene, has as yet presented no 

 indication of the intrusion of anything to interfere with its 

 uniformly sub-tropical character." ^ 



This is sufficiently striking ; but when we consider that this 

 enormous series of deposits, many thousand feet in thickness, 

 consists wholly of alternations of clays, sands, marls, shales, or 

 limestones, with a few beds of pebbles or conglomerate, not one 

 of the whole series containing irregular blocks of foreign mate- 

 rial, boulders, or gravel such as we have seen to be the essen- 

 tial characteristic of a glacial epoch ; and when we find that 

 this very same general character pervades all the extensive 

 Tertiary deposits of temperate North America, we shall, I think, 

 be forced to the conclusion that no general glacial epochs could 



1 Geological Magazine, 1876, p. 392. 



