Sir H. Hoicorth — Recent Changes of Level. 409 



beds below the Drift, but every evidence of continuous land 

 conditions. This old land-surface, with its living occupants, points 

 unmistakably to the general level having been considerably higher 

 very recently. 



Let us now turn to another district. I have already in previous 

 articles discussed the more recent history of the Arctic border lands 

 of North-Eastern Europe and Asia, and have shown that while in 

 the Mammoth age the Bear Islands were united to the mainland, 

 there was also a land-bridge between Asia and America by 

 which the animals could pass to and fro. In either case this was 

 followed by a great collapse along the whole sea-boai'd, by which 

 a large strip of land was submerged. The evidence of this is two- 

 fold, namely, the occurrence of large numbers of bones between the 

 Bear Islands and the mainland, where they have been dredged ; and 

 secondly, the occurrence of marine shells far inland in the valleys 

 of the Petchora, the Obi, and the Yenessei, showing quite a recent 

 elevation. In some cases these marine beds overlie the Mammoth 

 beds and thus enable us to fix the fact that the last upheaval has 

 been more recent than the last submergence in those latitudes. 

 If we turn to the eastern coast of Asia, and examine the fauna 

 and flora of the Island of Saghalien and the Northern Island of 

 Japan, separated from the Southern Island by that great zoological 

 " divide " Blackeston's Line, we shall be constrained to the con- 

 clusion that these two islands, forming so integral a part of 

 the Palaaarctic region, can only very recently have been separated 

 from the mainland, and that we have hei"e, as in the broken bridge 

 of Bering Straits, fresh evidence of a great and recent collapse of 

 the land. 



If we turn to America, we shall find some of the most experienced 

 geologists in agreement as to there having been a very recent much 

 higher continental elevation there. This is shown by the submerged 

 valleys. Thus Prof. J. W. Spencer calls attention to the fact that 

 the original rocky floor of the Mississippi valley is buried to a depth 

 of 170 feet at La Closse, 1000 miles from the Gulf of Mexico; 

 while at New Orleans the boring of 630 feet below the sea-level 

 does not penetrate the Southern Drift, nor even reach to its highest 

 members; this, as he says, points to the fact that the country 

 drained by the upper waters of the Mississippi must have stood 

 many hundred feet higher than it does now relatively to the region 

 at its mouth, while that same region has also been greatly elevated. 

 " Passing," he says, " from the buried channels of the Mississippi 

 to its continuation, now submerged beneath the waves of the Gulf 

 of Mexico, we find evidence indicating such a stupendous continental 

 elevation as to be almost incredible were it not supported by 

 collateral evidence upon both the Pacific and Atlantic coasts. The 

 surroundings off the coast of the delta of the Mississippi indicate 

 the outer margin of the continental plateau as submerged to a depth 

 of 3600 feet, indented by an embayment of another hundred fathoms 

 in depth, at the head of which there is a valley, a few miles wide, 

 bounded by a plateau from 900 to 1200 feet above its floor. This 



