THE FIRST FORESTS OF MODERN TYPE. 201 



never regained, after the Glacial period, the exuberancvi of 

 plant life which they presented in the Miocene and earlier 

 Pliocene ; and we shall find that this statement applies to the 

 world of animals as well as to that of plants. This reduction 

 was more extreme in Europe than in Eastern Asia and Eastern 

 America, and the fact is thus accounted for in a recent lecture 

 by Prof. Asa Gray : — 



" I conceive that three things have conspired to this loss. 

 First, Europe, hardly extending south of latitude 40°, is all 

 within the limits generally assigned to severe glacial action. 

 Second, its mountains trend east and west, from the Pyrenees 

 to the Carpathians and the Caucasus beyond, near its southern 

 border ; and they had glaciers of their own, which must have 

 begun t^ '^ir operations, and poured down the northward flanks, 

 while the plains were still covered with forest, on the retreat from 

 the great ice-wave coming from the north. Attacked both on 

 front and rear, much of the forest must have perished then and 

 there. Third, across the line of retreat of those which may 

 have flanked the mountain-ranges, or were stationed south of 

 them, stretched the Mediterranean, an impassable barrier. Some 

 hardy trees may have eked out their existence on the northern 

 shore of the Mediterranean and the Atlantic coast. But we 

 doubt not, Taxodium and Sequoias, Magnolias and Liquidam- 

 bars, and even Hickories and the like, were among the missing. 

 Escape by the east, and rehabilitation from that quarter until a 

 very late period, were apparently prevented by the prolongation 

 of the Mediterranean to the Caspian, and thence to the Siberian 

 ocean. If we accept the supposition of Nordenskiold, that 

 anterior to the Glacial period, Europe was 'bounded on the 

 south by an ocean extending from the Atlantic over the present 

 deserts of Sahara and Central Asia to the Pacific,' rJl chance 

 of these American types having escaped from or re-entered 

 Europe from the south and east, is excluded. Europe may 

 thus be conceived to have been for a time somewhat in the 

 condition in which Greenland is now, and indeed to have been 



