1 70 THE EARLIEST MEN 



on its banks and valley." No doubt, but are we 

 quite clear that it has always " kept time," even 

 if we are quite clear that we know that 

 " time ? " Professor Keith makes the " provisional 

 estimate " that subsidence has taken place at the 

 rate of one foot per thousand years, and apparently 

 that this rate has been a constant one. Thus he is 

 able to date his skeletons at ten, twenty, thirty 

 thousand years ago. But in this calculation all 

 reference is omitted to the very differing physical 

 conditions which must have existed during the 

 long space of years which has rolled by since the 

 Thames began its work. Nothing seems clearer 

 than the fact that during quite a considerable 

 part of that era, the volume of water discharged 

 must have been enormously greater than that 

 which has flowed under London Bridge since that 

 was built. And this greater volume, of course, 

 would mean a much more rapid erosion. Which, 

 in its turn, would wholly upset the calculation as 

 to time based upon it.* 



It is quite clear that estimates of time of this 

 character, however picturesque they may be, and 

 however seductive to the journalist in search of a 

 sensation, are quite useless and not to be depended 

 upon. The same story applies to other geological 



* That the calculation in quest ion which would place the man of 

 Galley Hill at 200,000 years ago, and those of Neanderthal at 

 500,000 to i ,500,000 years ago, are not acceptable to other workers, 

 is obvious from the criticism of the work in question by M. M. 

 Boule in L Anthropologie (vol. xxiii, p. 218), in which, after speak- 

 ing of the author as " peu familiaris^ certainement avec les ques- 

 tions de geologic et d arch^ologie prehistorique," he goes on to 

 quote his estimates of age, and speak of their " imprudente 

 hardiesse." 



