372 REroRT— 1900. 



I may point out here that Daubree's experiments by no means support 

 the view that crystalline rocks are rapidly attacked by superheated water, 

 but rather demonstrate the contrary. At a pressure which Daubree esti- 

 mated at more than 1,000 atmospheres, and at a red heat, water failed to 

 appreciably attack, after many weeks, sanidine, oligoclase, pyroxene, or 

 potash mica. The contrary is generally inferred from the general atten- 

 tion which has been paid to his experiments on glass and obsidian. The 

 early igneous rock crust from the general prevalence of conditions of slow 

 cooling would almost certainly have been highly crystalline. 



The notion that exce2)tionaf vidcmisiu prevailed in the earliest times 

 appears unproved. The traps and dykes of archa!ai\ rocks are not always 

 evidence of subacrial outbursts — the Lewisian and Torridonian rocks of 

 Scotland may be quoted as examples, where, although there is much injec- 

 tion of igneous matter, there is no evidence of corresponding volcanic action. 

 And, again, it may be well questioned, granting even excessive volcanic 

 action, how far it would affect the methodical supply to the ocean of dis- 

 solved alkalies by the rivers. 



Early tides of gigantic height have been rather discredited. Any one 

 reading Professor G. Darwin's delightful book on ' Tides ' will be struck 

 with the caution and moderation of the writer. He maintains ' the pos- 

 sibility that a considerable part of the changes due to tidal friction may 

 have occurred within geological history,' yet thinks it ' probable that the 

 greater part of the changes due to tidal friction must be referred back to 

 pi-e-geological times when the planet was partially or entirely molten.' 

 Tliis involves, of course, that the epoch of most violent activity prevailed 

 in pre-geological times before the work of denudation had begun. And 

 here, again, even admitting higher tides, it may be seriously asked on 

 what grounds we assume such higher tides to effect solvent denudation 

 positively rather than negatively. If the tides of to-day rose so as to 

 encroach five miles further on the coasts, would the loss of soil area re- 

 sulting compensate for the gain of bare superficial rock swept by the sea ? 

 A soil but 10 cms. deep may expose an area 50,000 times its superficial area 

 to the solvent actions of hygroscopic water and rain, CO.^, organic acids, »fec. 

 Professor Perry, writing in ' Natm'e,' has suggested the possibility of 

 diminished sun-heat at a period as recent as some 50 x 10'' years ago. But 

 so far as I know, Professor Perry has not gone further than to suggest 

 the possibility of this external interference with the orderly succession of 

 events in the earth. 



But finally in regard to all these surmises, interesting and valuable as 

 they undoubtedly are, can I do better than to refer to Sir A. Geikie's reading 

 of rock-testimony on this point 1 Sir A. Geikie seeks one hundred million 

 years as sufficient for the sedimentary history of the earth. His words are 

 recent — dating from his address to the Geological Section last year. The 

 evidence of the sedimentary rocks, he affirms, shows no more stupendous 

 mountain upheavals, volcanic eruptions, or greater violence in the sur- 

 rounding envelopes of atmosphere and ocean than occurred in more recent 

 periods or than we are acquainted with to-day. ' Even in the most 

 ancient of the sedimentary registers of the world's history not only is 

 there no evidence of colossal floods, tides, and denudation, but there is 

 incontestable proof of continuous orderly deposition such as may be 

 witnessed to-day in any quarter of the globe. The same tale with endless 

 additional detail is told all through the stratified formations down to those 

 which are in course of accumulation at the present day,' 



