FLINT IMPLEMENTS FOUND IN KENT’S CAVERN. an 
the era when some of the mammals then living were of species 
which had become extinct before historic times. Hence, whilst 
a geologist would hesitate to pronounce a deposit of palzeolithic 
age merely because he had found in it a solitary unpolished flint 
implement, his hesitation would vanish in a moment if he also 
detected a relic of the Cave bear, or Woolly rhinoceros, or any 
other extinct mammal. 
It must be scarcely necessary to say that the materials used for 
tools and the character of the tools themselves are nothing more 
than indications of states of civilization, and cannot be taken as 
representatives of definite periods of time for the entire world. 
The scheme just described is intended to apply to Western Europe, 
as already stated; and no attempt need be here made to open the 
question of its applicability to any other parts of the world. 
Again, the successive Ages were not necessarily or probably of 
equal duration. It is probable, however, that the tenacity of any 
phase of civilization amongst any human race may be safely re- 
garded as.a direct function—to speak mathematically —of the 
rudeness of that phase; the greater the one the greater the other. 
Whether the men who polished their flint tools were the descen- 
dants or the conquerors of those who did not, it may not be 
possible to determine, though the question must be one of grave 
chronological significance. 
It is, no doubt, true that by following the geological method, 
evidences of a rude civilization may sometimes be found deposited 
on such as indicate a comparatively advanced state of society. 
This was, of course, the case in Britain when Saxon rudeness 
followed Roman culture; but whilst the Archeologist must not 
lose sight of their possible occurrence, such cases are in all proba- 
bility very exceptional. 
Whilst, however, it may be comparatively easy to determine the 
Age to which a given relic belongs, that determination will do 
little or nothing to fix its date in years, or to determine the 
chronological value of the intervals between our successive stepping 
stones. To assist us in this matter let us proceed to Denmark, 
where the naturalists have found a scheme of chronology in the 
peat bogs. 
Denmark has been described as a land of beech trees, and on 
the surface of its bogs are found the débris or refuse of trees of 
