208 . Report of the State Geologist. 



gradually approximate exististing forms. The plants which are 

 considered characteristic of a tropic climate, as Palms and 

 the Banana, do not extend beyond the northern parts of Eng- 

 land and of Germany. 



The Oligocene and the Miocene have been the object of pro- 

 found discussions from the point of view which we are consider- 

 ing In central Europe, the Mammals and Corals show tropical 

 characteristics. The marine Mollusks are tropical with forms 

 .which have remained in the present Mediterranean; the fresh 

 water and terrestrial Mollusks, the insects and the plants are sub- 

 tropical in the Oligocene and the Lower Miocene, then they 

 assume the characteristics of the fauna of southern Europe ; the 

 birds differ little from the present species, but include also tropi- 

 cal forms. To sum up, the climate was warm, and the winters 

 were mild, as is proved by the distribution of the fossil plants 

 in the annual deposits of the lakes of the south. 



The northern regions possessed at this epoch a temperate 

 climate; the plants of Grinnell land, 83° of north latitude, those 

 of Iceland, Spitzbergen, etc., studied by Heer, are Pines, Elms, 

 l^ymphacea, Cyperus, Carex and Potamogeton. In Spitzbergen, 

 at 70°, we find even Magnolias and the Gingko, which are char- 

 acteristic of the warm temperate flora. Heer has pointed out 

 that this flora requires a moderately high temperature, from 17.5° 

 to that attained at the present day, and the difference reaches 

 even as far as 28° for Grinnell land. 



But, as is demonstrated by Neumayr, these conclusions hold 

 good only for Europe. The lowering of the temperature at the 

 Miocene epoch is much more marked in Xorth and South 

 America; Europe at that time had probably a much milder 

 climate than existed in other parts of the world. In the 

 central portion of JVorth America, and in Chili especially, the 

 temperature appears to have been very little higher than it is at 

 present. 



After the period of the Upper Miocene the reef corals defini- 

 tively disappeared from Europe ; the last of them are found in 

 Malta and in Asia Minor. During the Pliocene they are found 

 only in the Ped Sea, that is to say, they reached the limit which 

 has been their boundary to the present day. The Pliocene flora 

 of France, with its Bamboos and Laurels, is still a warm flora ; 

 the plants which at present do not pass beyond 35°, reached at 

 that time to 40°. But the temperate elements which exist now 

 in the same regions are already abundantly represented. 



Climate of the Pliocene and Quaternary — We now come 

 to an epoch very near our own, where the elements of comparison 

 are directly drawn from living nature, and thus allow more pre- 

 cise inductions. 



In England, the marine deposits succeed each other uninter- 

 ruptedly at certain points, starting from the Pliocene. But on 

 the one' hand almost all the marine shells of the Pliocene and 



