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 North efn 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.” 1 
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. 892. 
