Immediately above these Upper Cretaceous beds we have the great Lignite Tertiary of the West--the Laramie group of recent American reports--abounding in fossil plants, at one time regarded as Miocene, but now known to be Lower Eocene, though farther south extending upward toward the Miocene age.[EP] These beds, with their characteristic plants, have been traced into the British territory north of the forty-ninth parallel, and it has been shown that their fossils are identical with those of the McKenzie River valley, described by Heer as Miocene, and probably also with those of Alaska, referred to the same age.[EQ] Now this truly Eocene flora of the temperate and northern parts of America has so many species in common with that called Miocene in Greenland that its identity can scarcely be doubted. These facts have led to scepticism as to the Miocene age of the upper plant-bearing beds of Greenland, and more especially Mr. J. Starkie Gardner has ably argued, from comparison with the Eocene flora of England and other considerations, that they are really of that earlier date.[ER] [EP] Lesquereux's "Tertiary Flora"; "White on the Laramie Group"; Stevenson, "Geological Relations of Lignitic Groups," American Philosophical Society, June, 1875; Dawson, "Transactions of the Royal Society of Canada," vol. iv.; Ward, "Bulletin of United States Geological Survey." [EQ] G. M. Dawson, "Report on the Geology of the Forty-ninth Parallel," where full details on these points may be found. "Transactions of the Royal Society of Canada," vol. iv. [ER] "Nature," December 12, 1878. In looking at this question, we may fairly assume that no climate, however equable, could permit the vegetation of the neighbourhood of Disco in Greenland to be exactly identical with that of Colorado and Missouri, at a time when little difference of level existed in the two regions. Either the southern flora migrated north in consequence of a greater amelioration of climate, or the northern flora moved southward as the climate became colder. The same argument, as Gardner has ably shown, applies to the similarity of the Tertiary plants of temperate Europe to those of Greenland. If Greenland required a temperature of about 50°, as Heer calculates, to maintain its Eocene flora, the temperature of England and that of the Southwestern States must have been higher, though probably more equable, than at present.