Presidential Address. 227 



along the borders of the subsiding land, which was probably 

 covered with the decomposing rock arising from, long ages 

 of sub-aerial waste. 



In the coal-formation age, its characteristic swampy flats 

 stretched in some places far into the shallower parts of the 

 ocean. 1 In the Permian, the great plicated mountain mar- 

 gins were fully developed on both sides of the Atlantic. 

 In the Jurassic, the American continent probably ex- 

 tended further to the sea than at present. In the Wealden 

 age, there was much land to the west and north of Great 

 Britain, and Professor Bonney has directed attention to the 

 evidence of the existence of this land as far back as the 

 Trias, while Air. Starkie Gardiner has insisted on connecting 

 links to the southward as evidenced by fossil plants. So late 

 as the Post-glacial, or early human period, large tracts, now 

 submerged, formed portions of the continents. On the other 

 hand, the interior plains of America and Europe were often 

 submerged. Such submergences are indicated by the great 

 limestones of the Palaeozoic, by the chalk and its representa- 

 tive beds in the Cretaceous, by the Nummulitic formation 

 in the Eocene, and lastly by the great Pleistocene submer- 

 gence, one of the most remarkable of all, one in which nearly 

 the whole northern hemisphere participated, and which was 

 probably sejDarated from -the present time by only a few 

 thousands of years. 2 These submergences and elevations 

 were not always alike on the two sides of the Atlantic. The 

 Salina period of the Silurian, for example, and the Jurassic, 

 show continental elevation iu America not shared by Europe. 

 The great subsidences of the Cretaceous and the Eocene were 

 proportionally deeper and wider on the eastern continent, 

 and this and the direction of the land being from north to 

 south, cause more ancient forms of life to survive in America. 



1 I have shown the evidence of this in the remnants of Carboni- 

 ferous districts once more extensive on the Atlantic coast of Nova 

 Scotia and Cape Breton {Acadian Geology.) 



2 The recent surveys of the Falls of Niagara coincide with a great 

 manj- evidences to which I have elsewhere referred in proving that 

 the Pleistocene submergence of America and Europe came to an 

 end not more than ten thousand years ago, and was itself not of 

 very great duration. Thus in Pleistocene times the land must have 

 been submerged and re-elevated in a very rapid manner. 



