LIFE ON THE EARTH. 165 



Moreover, a warmer atmosphere, whether of 

 greater total mass or not, would hold more moisture 

 in suspension, and thus the tendency to equalize 

 temperatures might probably be augmented, both 

 by the transport of aqueous vapour to the coolest 

 parts, and by the wider canopy of clouds which are 

 well known to be effective in preventing the waste- 

 ful radiation of heat from the surface of the earth. 

 Thus all these inquiries into the greater diffusion 

 of warmth over the surface by oceanic currents the 

 greater flow of heat from the interior of the earth, 

 and the greater resistance to the escape and waste 

 of this heat, by the surrounding atmosphere concur 

 in shewing that causes really founded in nature, and 

 still operating, may be appealed to for solution of 

 the interesting questions regarding ancient climate. 

 Neither perhaps is fully sufficient singly to explain 

 the phenomena, but they are of a nature to be com- 

 bined without improbability into a general and satis- 

 factory solution of the problem. 



PHYSICAL ASPECTS OF THE EARTH. 



The rich variety of the earth's surface, as it is 

 now possessed by man, is the legacy of many long 

 ages of busy nature, labouring to upheave the moun- 

 tains, and depress the seas, and carefully storing up 

 the treasures of those distant years for the enjoy- 



