22 THE AGE OF THE EARTH 



existed where oceans are now spread out ; and clear and 

 open oceans may have existed where our continents now 

 stand.' Not the least interesting result would be the 

 test of this hypothesis, which would probably be forth- 

 coming as the result of boring into the floor of a deep 

 ocean ; for although, as Darwin pointed out, it is likely 

 enough that such rocks would be highly metamorphosed, 

 yet it might still be possible to ascertain whether they 

 had at any time formed part of a continental deposit, and 

 perhaps to discover much more than this. Such an 

 undertaking might be carried out in conjunction with 

 other investigations of the highest interest, such as the 

 attempt to obtain a record of the swing of a pendulum 

 at the bottom of the ocean. 



We now come to the strictly biological part of our 

 subject — to the inquiry as to how much of the whole 

 scheme of organic evolution has been worked out in the 

 time during which the fossiliferous rocks were formed, 

 and how far, therefore, the time required by the geologist 

 is sufficient. 



It is first necessary to consider Lord Kelvin's sugges- 

 tion that life may have reached the earth on a meteorite — 

 a suggestion which might be made the basis of an attempt 

 to rescue us from the dilemma in which we were placed 

 by the insufficiency of time for evolution. It might be 

 argued that the evolution which took place elsewhere 

 may have been merely completed, in a comparatively 

 brief space of time, on our earth. 



We know nothing of the origin of life here or elsewhere, 

 and our only attitude towards this or any other hypo- 

 thesis on the subject is that of the anxious inquirer for 

 some particle of evidence. But a few brief considerations 

 will show that no escape from the demands for time can 

 be gained in this way. 



Our argument does not deal with the time required for 

 the origin of life, or for the development of the lowest 

 beings with which we are acquainted from the first formed 

 beings, of which we know nothing. Both these processes 

 may have required an immensity of time ; but as we know 



