G. W. Bulman — The Geological Chronometer. 125 



evaporation — owing to greater heat of the earth, and con- 

 sequently rainfall — was greater. Only if this state of things is shifted 

 back beyond the period of the formation of our earliest stratified 

 systems, can we escape the conclusion of greater geological activity 

 in the past. And the greater the rainfall the greater the derfUdationj 

 and consequent rock-making. This quicker formation, again, would 

 probably not be shown in the rocks themselves. 



(2) There may have been a larger amount of C Oj in the atmo- 

 sphere. In the original atmosphere of the globe there was probably 

 a very large quantity of this gas. There may have remained in the 

 atmosphere of the early geological ages an amount far in excess of 

 the present supply. 



(3) There may have been greater exuberance of life when the 

 waters of the ocean were warmer, as they once must have been on 

 the hypothesis of a cooling globe. 



Greater rainfall, more Oj in the atmosphere, and a warmer ocean, 

 all must once have been : they may have been late enough in time to 

 affect the rate of deposition of the known stratified rocks. The 

 question, then, really is, are we justified in putting them so far back 

 as to make them anterior to the beginning of geological history ? 

 Those who are demanding more and more time must remember that 

 the longer the period granted for the laying down of the stratified 

 systems, the nearer we get to the epoch when the activity of 

 geological agents must have been considerably greater than it is 

 to-day. And if they assume that all the known stratified rocks were 

 formed at the present slow rate of deposition, they leave unaccounted 

 for the great series of strata which must have been laid down when 

 geological activity was greater. They must appeal not merely to 

 the imperfection of the record, but to its total absence so far as 

 concerns the period before the present slow rate of deposition began. 



Professor Poulton is at great pains thus to cut away the ground 

 under the feet of the geologist who would " hurry up the process of 

 rock formation." But even granting all that is claimed to have been 

 proved, the biologist only gets in this way some 400,000,000 years. 

 And this is so obviously too little that it seems hardly worth while to 

 have troubled the geologist at all. Speaking of that curious organism 

 Peripatus, which has been variously classed in the zoological scheme, 

 Professor Poulton says : — " Peripatus is not known as a fossil. 

 Peripatus has come down, with but little change, from a time, on 

 a moderate estimate, at least twice as remote as the earliest known 

 Cambrian fossil." 



Now, if we put back the origin of Peripatus to a time as far 

 anterior to the Cambrian as the Cambrian is to the present day, how 

 far must we put back the origin of the simplest form of life ? Well, 

 Peripatus is a somewhat advanced organism — about the level of the 

 insects — and on the assumption, approved by Professor Poulton, that 

 evolution is slower among the simpler organisms we should perhaps 

 place the first appearance of life on the globe as much before 

 Peripatus as the origin of Peripatus is before the present. This 

 places the commencement of life at a point four times as remote from 



