276 MAN'S PLACE IN THE GEOLOGICAL RECORD. 



the Chalk formation of another region, still we know that 

 it stands intermediate between the Oolite and Tertiary, and 

 can therefore assign to it a place relatively to these forma- 

 tions. In some region yet unexplored a whole suite of 

 strata may be discovered older than our Carboniferous, and 

 yet younger than our Old Red, and in such a case geolo- 

 gists would give the new formation a name, and place it as 

 intermediate between these two systems. It would disturb 

 no established order, but merely render more complete the 

 sequence, like the interpolation of a hitherto unknown reign 

 in the dynasties of human history. The geological record 

 is thus a thing of mere sequence an inconceivable amount 

 of unexpressed time, during which certain events follow each 

 other in definite order. How many ages have elapsed since 

 the first deposition of the Laurentian strata we cannot tell ; 

 how many centuries were spent in the formation of the 

 Coal-measures of any locality, we can only, estimating from 

 existing operations, offer the widest conjecture. But we 

 can affirm with certainty, and this is a great point gained, 

 that one rock-system is younger than another ; that these 

 rock-systems follow in the order above given ; that accord- 

 ing to our present knowledge invertebrate life preceded the 

 vertebrate ; that fishes preceded reptiles, reptiles birds, and 

 birds mammalia.* We can also affirm, what it is the ob- 

 ject of the present Sketch to prove, that as there has been 

 an ascent in time from lower to higher forms of life, so 

 Man, being the highest known creature, comes latest on the 

 geological stage, and that evidences of his existence are to be 

 found only in the most recent and superficial formations. 



It will be seen from the preceding statements that the 

 geological record is avowedly indefinite and defective in- 

 definite, as it deals only with relative time ; and defective, 

 as many strata cannot be assigned to their proper positions, 

 * See tabulation of ascending orders, p. 29. 



