THE DATE OF THE GLACIAL PERIOD. 353 



pendent upon unknown conditions in the past, that it is 

 very difficult to estimate the result for any long period of 

 time. Occasionally a quarter of an inch of stalagmite 

 accretion has been known to take place in a cavern in a 

 single year, while in Kent's Cavern, over a visitor's name 

 inscribed in the year 1688, a film of stalagmite only a 

 twentieth of an inch in thickness has accumulated. If, 

 therefore, we could reckon upon a uniformity of conditions 

 stretching indefinitely back into the past, we could deter- 

 mine the age of these oldest remains of man in Kent's 

 Hole by a simple sum in arithmetic, and should infer that 

 the upper layer of stalagmite required 240,000 years, and 

 the lower 576,000 years, for their growth, which would 

 carry us back more than 700,000 years, and some have not 

 hesitated to affix as early a date as this to these lowest 

 implement-bearing gravels. 



But other portions of the cave show an actual rate of 

 accretion very much larger. Six inches of stalagmite is 

 there found overlying some remains of Romano-Saxon 

 times which cannot be more than 2,000 years old. As- 

 suming this as the uniform rate, the total time required 

 for the deposit of the stalagmitic floors would still be about 

 70,000 years. But, as we have seen, the present rates of 

 deposition are probably considerably less than those which 

 took place during the moister climate of the Glacial epoch. 

 Still, even by supposing the rate to be increased fourfold, 

 the age of this lower stratum would be reduced to only 

 12,000 years. So that, as Mr. James Geikie well main- 

 tains, " Even on the most extravagant assumption as to 

 the former rate of stalagmitic accretion, we shall yet be 

 compelled to admit a period of many thousands of years 

 for the formation of the stalagmitic pavements in Kent's 

 Cavern." * We should add, however, that there is much 

 well-founded doubt whether the implements found in the 



* Prehistoric Europe, p. 83. 



