THE EARLIEST MEN 167 



is the statement in books on architecture that the 

 Early English period of Gothic belonged to the 



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thirteenth, and the Decorated to the fourteenth 

 century. It would be exceedingly convenient and 

 enlightening if we were able to say that the fourth 



ice age extended from B.C. to B.C. , or 



even to say that it covered so many years, and was 

 approximately so many years ago. It is not the 

 fault of geologists that this cannot be done, or has 

 not been done. Numerous have the efforts been 

 to solve the question, and equally diverse the 

 answers made to the riddle. I shall not here refer 

 to the very varying views which have been expressed 

 by scientific authorities as to the age of the world, 

 but will content myself by saying a few words as 

 to the so-called " geological clocks." What is wanted 

 to solve the question under consideration, is some 

 kind of standard of comparison between past and 

 present processes. For instance, no one now doubts 

 that with exceptions which need not here be 

 considered the processes which have shaped the 

 world as it now is, are the same kind of processes 

 which are shaping the world into what it will be 

 in ages yet to come. If we could accurately measure 

 the result of one of these processes to-day, and 

 then compare it with the result of one of a similar 

 process in the past, we surely ought to be able to 

 estimate the amount of time which it would take 

 that process to bring about that result. 



In other words, we should have a " geological 

 clock." Before mentioning a few instances of these, 

 it may be as well to point out that a clock is useless 

 as a measure of time, unless it is invariable in its 



