108 EXPEDITION OF THE "CHALLENGER" m 



years ago, was held only by a small minority of 

 English geologists — Lyell, Scrope, and De la Beche 

 • — but now, thanks to the long-continued labours 

 of the first two, and mainly to those of Sir Charles 

 Lyell, has gradually passed from the position of a 

 heresy to that of catholic doctrine. 



Applied within the limits of the time registered 

 by the known fraction of the crust of the earth, 

 I believe that uniformitarianism is unassailable. 

 The evidence that, in the enormous lapse of time 

 between the deposition of the lowest Laurentian 

 strata and the present day, the forces which have 

 modified the surface of the crust of the earth were 

 different in kind, or greater in the intensity of 

 their action, than those which are now occupied in 

 the same work, has yet to be produced. Such 

 evidence as we possess all tends in the contrary 

 direction, and is in favour of the same slow and 

 gradual changes occurring then as now. 



But this conclusion in nowise conflicts with the 

 deductions of the physicist from his no less clear 

 and certain data. It may be certain that this 

 globe has cooled down from a condition in which 

 life could not have existed ; it may be certain that, 

 in so cooling, its contracting crust must have 

 undergone sudden convulsions, which were to our 

 earthquakes as an earthquake is to the vibration 

 caused by the periodical eruption of a Geyser ; but 

 in that case, the earth must, like other respectable 

 parents, have sowed her wild oats, and got through 



