16 Probable Temperature during the Tertiary Period. 



by some palms, we shall have acquired the means of forming 

 a sufficient number of inductions, all tending to prove the 

 high temperature of the first period of the tertiary strata. I 

 shall give, perhaps, a greater degree of certainty to my 

 inductions, if I bring before our consideration the ancient 

 state of the Paris basin, as compared with its present one. I 

 find there, in effect, on one side, a great number of animals 

 whose races are annihilated ; and, on the other, the soil occu- 

 pied by new races, and the nearest seas peopled by species of 

 which ninety-nine hundredths did not formerly exist. I find 

 also, in this comparison, the proofs of profound changes 

 which have taken place in the circumstances of existence of 

 living creatures : but I will not pursue this interesting sub- 

 ject ; it would demand more space for developement than I 

 can give it here. 



From what I have just shown, it appears to me that we 

 may draw the following conclusions : — 



1. The first tertiary period took place under an equatorial 

 temperature; and, according to all probability, one many de- 

 grees hotter than the present temperature of the equator. 



2. During the second period, the beds of which occupy 

 the centre of Europe, the temperature has been similar to 

 that of Senegal and of Guinea. 



3. The temperature of the third period, at first a little 

 more elevated than ours in the basin of the Mediterranean, has 

 become similar to that which we experience. In the north, the 

 species of the north are fossil ; in the south, those of the south. 



Thus, since the commencement of the tertiary strata, the 

 temperature has been constantly diminishing. Passing, in 

 our climates, from the equatorial to that which we now enjoy, 

 it is easy to measure the difference. 



Without doubt, naturalists, supporting themselves upon 

 theories concerning heat, have been able to conjecture, a 

 priori, the changes of temperature of which I have just 

 spoken : it is curious, nevertheless, to see their conjectures 

 confirmed by a long- neglected science, which no one had yet 

 thought of directing towards this entirely novel end. 



This question respecting temperatures might be resumed 

 for the secondary strata ; but observations and materials are 

 wanting. This is not -the only one in the domain of con- 

 chology ; many others are of no less importance : biology, 

 for example, destined to make us acquainted with the laws of 

 the developement of life on the surface of the earth within 

 time and space, will draw from conchology numerous mate- 

 rials. But biology is a science yet to be formed. Lamarck 

 has discovered it: who shall lay its foundations ? — E. S. C. 



