168 EXTINCT MAMMALIA ABOVE DKIFT. [Oh. XII. 



valley of the Niagara, containing shells of the genera Melania, Lymnea, 

 Planorbis, Valvata, Cyclas, TJnio, Helix, &c, all of recent species, from 

 which the boues of the great Mastodon have been taken in a very perfect 

 state. Yet the whole excavation of the ravine, for many miles below 

 the Falls, has been slowly effected since that fluviatile deposit was thrown 

 down. 



Whether or not, in assigning a period of more than 30,000 years for 

 the recession of the Falls from Queenstown to their present site, I have 

 over or under estimated the time required for that operation, no one can 

 doubt that a vast number of centuries must have elapsed before so great 

 a series of geographical changes were brought about as have occurred 

 since the entombment of this elephantine quadruped. The freshwater 

 gravel which incloses it is decidedly of much more modern origin than 

 the drift or boulder clay of the same region.* 



Other extinct animals accompany the Mastodon giganteus in the post- 

 glacial deposits of the United States, among which the Castoroides ohi- 

 oensis, Foster and "Wyman, a huge rodent allied to the beaver, and the 

 Capybara may be mentioned. But whether the "loess," and other 

 freshwater and marine strata of the Southern States, in which skeletons 

 of the same Mastodon are mingled with the bones of the Megatherium, 

 Mylodon, and Megalonyx, were contemporaneous with the drift, or were 

 of subsequent date, is a chronological question still open to discussion. 

 It appears clear, however, from what we know of the tertiary fossils of 

 Europe — and I believe the same will hold true in North America — that 

 many species of testacea and some mammalia, which existed prior to the 

 glacial epoch, survived that era. As European examples among the warm- 

 blooded quadrupeds, the Eleplias primigenius and Rhinoceros tichorinus 

 may be mentioned. As to the shells, whether freshwater, terrestrial, or 

 marine, they need not be enumerated here, as allusion will be made to 

 them in the sequel, when the pliocene tertiary fossils of Suffolk are 

 described. The fact is important, as refuting the hypothesis that the 

 cold of the glacial period was so intense and universal as to annihilate 

 all living creatures throughout the globe. 



That the cold was greater for a time than it is now in certain parts of 

 Siberia, Europe, and North America, will not be disputed ; but, before 

 we can infer the universality of a colder climate, we must ascertain what 

 was the condition of other parts of the northern, and of the whole south- 

 ern, hemisphere at the time when the Scandinavian, British, and Alpine 

 erratics were transported into their present position. It must not be for- 

 gotten that a great deposit of drift and erratic blocks is now in full pro- 

 gress of formation in the southern hemisphere, in a zone corresponding 

 in latitude to the Baltic, and to Northern Italy, Switzerland, France, and 

 England. Should the uneven bed of the southern ocean be hereafter 

 converted by upheaval into land, the hills and valleys will be strewed 

 over with transported fragments, some derived from the antarctic conti- 



* See Travels in K America, vol. i. chap, ii., and Principles of Geol. chap xiv. 



