THE ANTIQUITY OF MAN 217 



be admitted, by anthropologists, but to the 

 figures of geologists, and of geologists who have 

 specialised in glacial matters.* 



Penck, whose researches have been carried on 

 in the Alpine district, and who depends upon 

 the evidence of denudation! for his estimates, 

 may be regarded as the writer who amongst 

 recognised glacialists demands the largest allow- 

 ance of time, and Penck thinks that the post- 

 glacial period in which we now exist cannot have 

 lasted for less than 20,000 years. On the other 

 hand, Sollas (pp. 393 seq.), after tracing the his- 

 tory of mankind backward for 7,000 years, comes 

 to Asilian time, and states that " from this point 

 the beginning of the seventh millenium we 

 look backwards over the last glacial episode." 



De Geers, whose observations on the rate of 

 deposit of the laminated marine clays of Southern 

 Sweden at present seem to hold out some hope of 

 our having at last obtained a reliable geological 

 clock, claims that he has shown that it is 9,000 

 years since the ground on which the University 

 of Stockholm stands became free from ice (Wright, 

 W. B., p. 343). In this connection it may be noted 

 that a variety of " geological clocks " have been 

 set up from time to time during the last sixty 



* A remarkable example of the extraordinary differences of 

 estimate in these matters may be found in the fact that Professor 

 Sollas, a geologist, puts the Mousterian race of Chapelle-aux- 

 Saintes at a distance of twenty-five thousand years, whilst Pro- 

 fessor Keith, an anthropologist, will not be satisfied with less than 

 three hundred and fifty thousand. It must be admitted that the 

 discrepancy is remarkable. The fact is that no one has any real 

 idea of the periods of glacial time in terms of years. 



f Notoriously very dangerous and doubtful evidence, as all 

 will admit. 



