75 



and that no coal except a recent formation of lignite is found 

 from the tropics southward ; in a word, the whole of the deposits 

 of the southern hemisphere are comparatively recent, whereas 

 those of the northern are more or less ancient. 



" It is not merely by reasoning from analogy that we are led to 

 infer a diminution of temperature in the climate of the lands now 

 situated in the northern hemisphere ; there are direct proofs in 

 confirmation of the same doctrine," says Professor Lyell, " in the 

 only countries hitherto investigated by expert geologists where 

 we could meet with such proofs. It is not in England or 

 Northern France, but around the borders of the Mediterranean, 

 from the South of Spain to Calabria, and in the islands of the 

 Mediterranean, that we must look for conclusive evidence on 

 this question ; for it is not in strata where the organic remains 

 belong to extinct species, but where living species abound in a 

 fossil state, that a theory of climate can be subjected to the 

 eocperimentum cruris. The fossils of the Subapennine hills, and 

 their living analogues from the tropics, correspond in size; but 

 the individuals of the same species from the Mediterranean are 

 dwarfish, and appear degenerate and stunted in their growth, 

 for want of conditions which the Indian Ocean still supplies. 

 This evidence is not neutralized by any facts of a conflicting 

 character; such, for instance, as the association, in the same 

 group, of individuals referrible to species now confined to the 

 arctic regions. Whenever any of the fossil shells are identified 

 with living species at or near the equator, it is not in the North- 

 ern Ocean, but in the Southern that they must be sought." 



When geologists assumed an igneous globe undergoing refri- 

 geration, to account for the former high temperature of the 

 northern hemisphere, they imagined that the southern hemi- 

 sphere indicated the same kind of change, i. e. from hot to cold ; 

 but it will be observed that the changes are quite the reverse. 

 The sedimentary beds of equatorial America contain shells analo- 

 gous, and some identical, to those found only in the south tempe- 

 rate zone, and none indigenous to the seas of the northern hemi- 

 sphere. Those who may prefer the doctrine of a cooling globe to 

 account for the phenomena, are placed in the dilemma of making 

 the globe hot only in the northern hemisphere and colder at the 

 tropics than at present to agree with the observed facts. 



The variable temperature on the surface of the globe is pro- 



