THE LAWS OF GEOLOGICAL ACTION. 7 



" the actual configuration 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 con- 

 struction of our globe, but results of successive and complex 

 actions on a former state of things ; that, again, of similar 

 actions on another still more remote ; and so on, till the ori- 

 ginal 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 

 assured 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 simul- 

 taneous 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 comparative parvenus. We have also the clearest evidence 

 that the animals and plants which now inhabit the globe have 

 been preceded, over and over again, by other different assem- 

 blages of animals and plants, which have flourished in succes- 

 sive periods of the earth's history, have reached their culmina- 

 tion, 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 a greater or less extent, the lineal descendant of 

 the group which immediately preceded it in point of time, and 

 is more or less fully concerned with giving origin to the group 

 which immediately follows it. That this law of " evolution " 

 has prevailed to a great extent is quite certain ; but it does not 

 meet all the exigencies of the case, and it is probable that its 

 action has been supplemented by some still unknown law of a 

 different character. 



We shall have to consider the question of geological " con- 

 tinuity" again. In the meanwhile, it is sufficient to state that 

 this doctrine is now almost universally accepted as the basis 



