"In Eastern America, from the Carboniferous period onward, the centre of plant distribution has been the Appalachian chain. From this the plants and sediments extended westward in times of elevation, and to this they receded in times of depression. But this centre was non-existent before the Devonian period, and the centre of this must have been to the north-east, whence the great mass of older Appalachian sediment was derived. In the Carboniferous period there was also an eastward distribution from the Appalachians, and links of connection in the Atlantic bed between the floras of Europe and America. In the Devonian such connection can have been only far to the north-east. It is therefore in Newfoundland, Labrador, and Greenland that we are to look for the oldest American flora, and in like manner on the border of the old Scandinavian nucleus for that of Europe." "Again, it must have been the wide extension of the sea of the Corniferous limestone that gave the last blow to the remaining flora of the Lower Devonian: and the re-elevation in the middle of that epoch brought in the Appalachian ridges as a new centre, and established a connection with Europe which introduced the Upper Devonian and Carboniferous floras. Lastly, from the comparative richness of the later Erian[90] flora in Eastern America, especially in the St. John beds, it might be a fair inference that the north-eastern end of the Appalachian ridge was the original birthplace or centre of creation of what we may call the later Palæozoic flora, or a large part of that flora." [90] The term Erian is used as synonymous with Devonian, and probably should be preferred to it, as pointing to the best development of this formation known, which is on the shores of Lake Erie.