AuGusrT 20, 1897.] 
drift specimens belong to so late a date as 
these artistic cavern-remains, but the great- 
ly superior antiquity of even these to any 
Neolithic relics is testified by the thick 
layer of stalagmite which had been de- 
posited in Kent’s Cavern before its occupa- 
tion by men of the Neolithic and Bronze 
Periods. 
Towards the close of the period covered 
by the human occupation of the French 
caves there seems to have been a dwindling 
in the number of the larger animals consti- 
tuting the Quaternary fauna, whereas their 
remains are present in abundance in the 
lower and, therefore, more recent of the 
valley gravels. This circumstance may 
afford an argument in favor of regarding 
the period represented by the later French 
eayes as a continuation of that during 
which the old river gravels were deposited, 
and yet the great change in the fauna that 
has taken place since the latest of the cave- 
deposits included in the Paleolithic Period 
is indicative of an immense lapse of time. 
How much greater must have been the 
time required for the more conspicuous 
change between the old Quaternary fauna 
of the river gravels and that characteristic 
of the Neolithic Period ! 
As has been pointed out by Professor Boyd 
Dawkins, only thirty-one out of the forty- 
eight well-ascertained species living in the 
post-Glacial or River-drift Period survived 
into pre-historic or Neolithic times. We 
have not, indeed, any means at command 
for estimating the number of centuries 
which such an important change indicates; 
but when we remember that the date of the 
commencement of the Neolithic or Surface 
Stone Period is still shrouded in the mist of 
a dim antiquity, and that prior to that com- 
mencement the River-drift Period had long 
come to an end ; and when we further take 
into account the almost inconceivable ages 
that even under the most favorable condi- 
tions the excavation of wide and deep val- 
SCIENCE. 
277 
leys by river action implies, the remoteness 
of the date at which the Paleolithic Period 
had its beginning almost transcends our 
powers of imagination. 
We find distinct traces of river action 
from 100 to 200 feet above the level of ex- 
isting streams and rivers, and sometimes at 
a great distance from them; we observe old 
fresh-water deposits on the slopes of valleys 
several miles in width; we find that long 
and lofty escarpments of rock have receded 
unknown distances since their summits were 
first occupied by Paleolithic man; we see 
that the whole side of a wide river valley 
has been carried away by an invasion of the 
sea, which attacked and removed a barrier 
of chalk cliffs from 400 to 600 feetin height; 
we find that what was formerly an inland 
river has been widened out into an arm of 
the sea, now the highway of our fleets, and 
that gravels which were originally deposited 
in the bed of some ancient river now cap 
isolated and lofty hills. 
And yet, remote as the date of the first 
known occupation of Britain by man may 
be, it belongs to what, geologically speaking, 
must be regarded as a quite recent period, 
for we are now in a position to fix, with some 
degree of accuracy, its place on the geolog- 
ical scale. Thanks to investigations ably 
earried out at Hoxne in Suffolk, and at 
Hitchin in Hertfordshire, by Mr. Clement 
Reid, under the auspices of this Association 
and of the Royal Society, we know thatthe 
implement-bearing beds at those places un- 
doubtedly belong to a time subsequent to 
the deposit of the great chalky boulder clay 
of the eastern counties of England. It is, 
of course, self-evident that this vast deposit, 
in whatever manner it may have been form- 
ed, could not, for centuries after its deposi- 
tion was complete, have presented a surface 
inhabitable by man. Moreover, at a dis- 
tanee but little farther north, beds exist 
which also, though at a somewhat later date, 
were apparently formed under glacial con- 
