OF THE EARTH, 473 



cumulation of materials at the bottom of the oeeaiv 

 is a work infinitely slow: we are sure that such an ac- 

 cumulation as should produce the primary strata as we 

 now see them, must have occupied a space, from the 

 contemplation of which the mind shrinks. Whatever 

 that may be, the geological depth of the consecutive 

 series of any one stage of the surface, is the measure 

 of the time through which it was deposited: it is the 

 measure of the duration of that world which immedi- 

 ately preceded the one of which it forms the latest 

 stratified portion. 



Hence the duration of that state of the globe in 

 which its dry land consisted of the present primary 

 rocks alone, is measured by the nearest consecutive 

 mass of the present secondary strata ; and as we have 

 not yet examined into these, this question cannot be 

 investigated till at a future period of the present en- 

 quiry. But, for the same reason, we are competent 

 now to enquire of the duration of that world which 

 preceded the primary, because it is measured by those 

 strata, now, equally with the secondary, subject to 

 our inspection. The thickness of these strata we 

 know to be enormous, although subject to great 

 variety. But, in this variety of depth, the present 

 question of duration is not interested; since that must be 

 measured by the greatest, not by the least. How these 

 depths are discovered by geological observations and 

 inferences, was shown in a former chapter; and that 

 they extend to many miles was also proved. Their 

 absolute depth is not interesting in this enquiry, be- 

 cause we know not, in any case, the relation between 

 that and the time required to produce it. It is here 

 sufficient to show how the immensity of the one is 

 implied by the magnitude of the other. Yet it is also 

 interesting to observe comparatively, that a^the great- 

 est depth of the primary strata yet examined appear* 



