THE PRE- ADAMITE EARTH. 



The fourth, to which the name of Ligerian basin has been given, 

 covered part of the western provinces of France, as indicated 

 upon the map (fig. 181). 



462. It must not be understood, however, that during the 

 whole continuance of the Tertiary age, or even during any two 

 periods of it, these seas jnaintained the same circumscription or 

 corresponded exactly with the outlines given in this map. On 

 the contrary, the geological convulsions which took place between 

 period and period, produced such changes of level in the land as 

 completely to derange the outlines of land and water. Thus the 

 Anglo -Parisian basin not only changed its form and limits in 

 diiferent periods, but in one totally disappeared, while in the first 

 periods of the Tertiary age the Ligerian basin had no existence. 

 Previously to the convulsion in which the chain of the Pyrenees 

 was elevated, the Pyrenean basin covered the ground upon which 

 that r mge afterwards stood, but after their elevation its shores 

 were driven northwards and its dimensions considerably reduced. 

 These changes of the outlines of land and water will, however, 

 be more clearly explained in the account we shall give of the 

 successive periods of this age. 



463. The most striking characteristic of the fauna of the 

 Tertiary age, was the extraordinary development which took place 

 among vertebrated animals. It was then indeed that the land 

 was first peopled by those inammifers so remarkable for their 

 proportions and characters, such as the Anthracotheriums, the 

 Palceotheriums, the Anoplotheriums (fig. 182), the Dinotheriums, 

 the Toxodons, the Mastodons, the Sinilodons, the Grlyptodons 

 (fig. 183), the Megatheriums, the Megalonix, and many others. 

 It was then also that the continents were first peopled by birds 

 which would be pronounced colossal even beside the ostrich, and 

 with salamanders as large as the present crocodile. Around this 

 stupendous fauna was collected a floi a on a proportionate scale. 

 The seas were peopled by marine classes in a corresponding pro- 

 portion, and almost as varied as in our own day. 



464. The generic animal forms, peculiar to present tropical 

 climates, being found distributed indifferently in all latitudes, it is 

 inferred that a general tropical temperature, as in former periods, 

 prevailed, and that consequently no isothermal lines or climatolo- 

 gical distinctions existed upon the earth until the present period. 



465. Numerous indications are also found among the geological 

 phenomena, of the prevalence during this age of those slow and 

 gradual undulations of the earth's crust which are still in progress 

 in the north of Europe and elsewhere, independently of the more 

 violent class of convulsions by which period was divided from 

 period, fauna from fauna, and flora from flora. 



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