THE LAWS OF GEOLOGICAL ACTION. 7 



ural than the belief that the present continents and oceans have 

 always been where they are now ; that we have always had the 

 same mountains and plains; that our rivers have always had 

 their present courses, and our lakes their present positions, that 

 our climate has always been the same ; and that our animals 

 and plants have always been identical with those now familiar 

 to us. Nothing could be more natural than such a belief, and 

 nothing could be further removed from the actual truth. On 

 the contrary, a very slight acquaintance with geology shows us, 

 in the words of Sir John Herschel, that "the actual configura- 

 tion of our continents and islands, the coast-lines of our maps, 

 the direction and elevation of our mountain-chains, the courses 

 of our rivers, and the soundings of our oceans, are not things 

 primordially arranged in the construction of our globe, but re- 

 sults of successive and complex actions on a former state of 

 things; that, again, of similar actions on another still more re- 

 mote: and so on, till the original and really permanent state is 

 pushed altogether out of sight and beyond the reach even of 

 imagination; while on the other hand, a similar, and, as far as 

 we can see, interminable vista is opened out for the future, by 

 which the habitability of our planet is secured amid the total 

 abolition on it of the present theatres of terrestrial life." 



Geology, then, teaches us that the physical features which 

 now distinguish the earth's surface have been produced as the 

 ultimate result of an almost endless succession of precedent 

 changes. Palaeontology teaches us, though not yet in such as- 

 sured accents, the same lesson. Our present animals and plants 

 have not been produced, in their innumerable forms, each as we 

 now know it, as the sudden, collective, and simultaneous birth 

 of a renovated world. On the contrary, we have the clearest 

 evidence that some of our existing animals and plants made 

 their appearance upon the earth at a much earlier period than 

 others. In the confederation of animated nature some races 

 can boast of an immemorial antiquity, whilst others are com- 

 parative parvenus. We have also the clearest evidence that the 

 animals and plants which now inhabit the globe have been pre- 

 ceded, over and over again, by other different assemblages of 

 animals and plants, which have flourished in successive periods 

 of the earth's history, have reached their culmination, and then 

 have given way to a fresh series of living beings. We have, 

 finally, the clearest evidence that these successive groups of 

 animals and plants (faunae and florae) are to a greater or less 

 extent directly connected with one another. Each group is, to 



