cted the men, and the men in turn ejected the
bears, by the summary process of eating one another up. In any case the
freehold of the cave was at last settled upon our early French artist.
But the date of his occupancy is by no means recent; for since he lived
there the long cold spell known as the Great Ice Age, or Glacial Epoch,
has swept over the whole of Northern Europe, and swept before it the
shivering descendants of my poor prehistoric old master. Now, how long
ago was the Great Ice Age? As a rule, if you ask a geologist for a
definite date, you will find him very chary of giving you a distinct
answer. He knows that the chalk is older than the London clay, and the
oolite than the chalk, and the red marl than the oolite; and he knows
also that each of them took a very long time indeed to lay down, but
exactly how long he has no notion. If you say to him, 'Is it a million
years since the chalk was deposited?' he will answer, like the old lady
of Prague, whose ideas were excessively vague, 'Perhaps.' If you suggest
five millions, he will answer oracularly once more, 'Perhaps'; and if
you go on to twenty millions, 'Perhaps,' with a broad smile, is still
the only confession of faith that torture will wring out of him. But in
the matter of the Glacial Epoch, a comparatively late and almost
historical event, geologists have broken through their usual reserve on
this chronological question and condescended to give us a numerical
determination. And here is how Dr. Croll gets at it.

Every now and again, geological evidence goes to show us, a long cold
spell occurs in the northern or southern hemisphere. During these long
cold spells the ice cap at the poles increases largely, till it spreads
over a great part of what are now the temperate regions of the globe,
and makes ice a mere drug in the market as far south as Covent Garden or
the Halles at Paris. During the greatest extension of this ice sheet in
the last glacial epoch, in fact, all England except a small
south-western corner (about Torquay and Bournemouth) was completely
covered by one enormous mass of glaciers, as is still the case with
almost the whole of Greenland. The ice sheet, grinding slowly over the
hills and rocks, smoothed and polished and striated their surfaces in
many places till they resembled the _roches moutonnees_ similarly ground
down in our own day by the moving ice rivers of Chamouni and
Grindelwald. Now, since these great glaciations have occurr