TIME GEOLOGICAL. 219 



and time. Where the exertion of force is great, the time 

 for performance may be short ; but where the force is 

 small, the time must be proportionally prolonged. The 

 two elements are ever in inverse ratio ; and thus agents 

 in themselves comparatively insignificant may, during the 

 lapse of ages, accomplish most important results. It is 

 generally, therefore, to the cumulative effects of this inex- 

 haustible resource of TIME that the developists make their 

 last appeal contending that the progress of transmutation 

 is so gradual as not to be appreciable with the five or six 

 thousand years of man's observation. Admitting the 

 plausibility of the argument in existing nature, the geo- 

 logist appeals to the fossil world for evidence of these 

 insensible gradations, and he finds stratum after stratum 

 containing the same unchanged species, and then, in the 

 next stratum, at once and decidedly, the remains of a species 

 altogether new. This, if anything Ave can intelligibly de- 

 fine, is not genetic gradation, but pre-appointed creation ; 

 and as time is merely passive unless the law of specific pro- 

 gress obeys some active and controlling power, an eternity 

 of time will never affect it. 



In the present state of our knowledge, any attempt to 

 calculate geological knowledge by years is altogether futile ; 

 we can only indicate its vastness by the use of indefinite 

 terms, as " eras," and "epochs," and "cycles." It is cus- 

 tomary, however, to speak of pre-geological, geological, and 

 historical time meaning by pre-geological all that extends 

 backwards before the deposition of the fossiliferous rocks ; 

 by geological, all that is embraced between the earliest fos- 

 siliferous deposits and human history ; and by historical, all 

 to which a determinate chronological value can be assigned. 

 With regard to the first, it is an abysm which the human 

 intellect, even in its boldest flights, shrinks from exploring; 

 as to the last, important as it may seem to man, creationally 



