THE PRE-ADAMITE EAETH. 



present from all past periods, is the existence of the human 

 race among its fauna, the attributes of which are so peculiar as 

 to place it out of all analogy with the other classes of animals. 



561. Another striking physical difference between the present 

 and all former period*, consists in the different divisions of 

 the earth's surface into climatological zones, each zone having 

 its peculiar fauna and flora. In all former ages and periods, 

 including those which immediately preceded the present, no traces 

 of climatic distinctions have been found. It has been already 

 shown that the fossil fauna and flora of latitudes the most 

 different, are analogous to the fauna and flora of warm climates. 

 Now since this uniform temperature can only be ascribed to 

 the great predominance of the effects of the central heat of the 

 earth over those of solar radiation, it might naturally be supposed 

 that the change would have been gradual, and that as the surface 

 of the earth would have cooled down by degrees, climates would 

 have been gradually manifested, the first differing but slightly in 

 temperature, and then from period to period the difference 

 increasing, until at length the earth would arrive at its present 

 condition, exhibiting the extremes and means of the torrid 

 temperate, and frigid zones. 



Observation nevertheless has not as yet supplied any facts to 

 confirm such theoretical views. On the contrary, in the fifth 

 Tertiary period, which immediately preceded the present epoch, 

 it is certain that the higher latitudes had a climate similar 

 to that which now prevails towards the Line. Plants, now 

 limited to southern latitudes, flourished in Europe. The palms, 

 for example, which vegetated there, have completely disap- 

 peared, having retired to warmer regions. The elephant, rhino- 

 ceros, panther, and other tropical animals which abounded in 

 high latitudes, have also wholly disappeared there, and are limited 

 to those latitudes where a temperature prevails conformable to 

 their organisation. The bear still lives in Europe, but not the 

 species which is found entombed in the strata. 



562. To render the fossil fauna compatible with the existence 

 of isothermal lines, it has been supposed that the remains of 

 animals and plants, peculiar to warm climates, which are 

 deposited in the strata of high latitudes, may have been trans- 

 ported there by ocean currents. That such an hypothesis is 

 inadequate and inadmissible, is demonstrated by the universality 

 of the tropical fauna of all periods. The remains, especially of 

 land animals and vegetables, which could by any possibility 

 have been transported by such means, must necessarily have been 

 few and local, and would appear merely as exceptions and 

 anomalies among the fauna and flora proper to the climatic loca- 



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