CONSEQUENCES OF CENTRAL HEAT. 



Fig. 226. Vertical stems in the mine of Treuil, St. Etienne. 



limestones to that of the chalk, after which they suddenly retired to their 

 present limits ; in other words, the climate of Europe has grown successively 

 colder. 



First effect of cooling. The idea of complete fusion, and of cooling, which 

 the observation of the phenomena forcibly leads us to admit, also leads us to 

 conceive what must have taken place on the first consolidation of the globe's 

 surface. The first solid pellicle formed underwent, from cooling, more or 

 less contraction, and on this account must have broken in all directions, 

 from the action of the melted matter it covered, swimming in pieces on it8 

 surface, and uniting anew more or less irregularly, to be again broken. But 

 assuming greater consistence, and pressing more and more on the liquid 

 part, this must have gushed up through the rents, then more rare, and formed 

 above the crust projecting ridges, of more or less extent, which increased in 

 height in proportion as the resistance of the crust became greater, and 

 caused stronger and stronger reaction. Hence the first rugosities, the first 

 ridges formed on the surface of the globe, which possibly afforded the first 

 hold for the action of water, the precipitation of which took place, without 

 doubt, long before the temperature of the terrestrial crust had descended to 

 212 of Fahrenheit's thermometer, in consequence of the pressure exerted 

 by the vapour then diffused in the air. From that moment waves produced 

 debris, and arena'ceous matters, and sediments began to form. Probably 

 Jie water, at a high temperature, charged witli the principles disengaged 

 from the solidified masses, like lava of the present time, attacked the stony 

 matters, disintegrated and dissolved them, and subsequently formed chemical 

 deposit?, or consolidated the debris. In fact, we find deposits formed of 

 fragments, of rolled flints and of sands, in the most ancient layers yet exa- 

 mined, and before meeting with organic remains. 



All the solid layers formed beneath the first pellicle, like it, being sub- 

 jeoted to the law of contraction from cooling, must have been filled with 

 cracks in all directions ; therefore the whole terrestrial crust, thus formed, 

 -sould not have been as solid as might be at first imagined : it could noi 



