36 THEORY OP THE EARTH. 



the earth, for causes sufficient to produce the revo- 

 lutions and catastrophes, the traces of which are 

 exhibited by its crust : And if we have recourse to 

 the constant external forces with which we are as 

 yet acquainted, we shall have no greater success. 



Constant Astronomical Causes. 



The pole of the earth moves in a circle around 

 the pole of the ecliptic, and its axis is more or less 

 inclined to the plane of the ecliptic ; but these two 

 motions, the causes of which are now ascertained, 

 are much too limited for the production of effects 

 like those whose magnitude we have just been 

 stating. At any rate, their excessive slowness 

 would render them altogether inadequate to ac- 

 count for catastrophes which, as we have shewn, 

 must have been sudden. 



The same reasoning applies to all other slow 

 motions which have been conceived as causes of 

 the revolutions in question, chosen doubtless in 

 the hope that their existence could not be de- 

 nied, because it might always be easy to hold out 

 that their very slowness rendered them impercep- 

 tible. But whether they be true or not is of lit- 

 tle importance, for they explain nothing, as no 

 cause acting slowly could have produced sudden 

 effects. 



Admitting that there has been a gradual dimi- 

 nution of the waters ; that the sea has transport- 

 ed solid matters in all directions ; that the tern- 



