ARCHEOLOGY AND THE ANTIQUITY OF MAN. 103 



ascertained species living in the Post-glacial or river-drift period 

 survived into prehistoric 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 commencement the river-drift period had long come to an 

 end; and when we further take into account the almost inconceiv- 

 able ages that even under the most favorable conditions the excava- 

 tion of wide and deep valleys by river action implies, the remoteness 

 of the date at which the palaeolithic period had its beginning almost 

 transcends our powers of imagination. We find distinct traces of 

 river action from one hundred to two hundred feet above the level of 

 existing streams and rivers, and sometimes at a great distance from 

 them; we observe old fresh- water deposits on the slopes of the val- 

 leys several miles in width; we find that long and lofty escarpments 

 of rock have receded unknown distances since their summits were 

 first occupied by palaeolithic 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 four hun- 

 dred to six hundred feet in 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 de- 

 posited 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 posi- 

 tion to Hx with some degree of accuracy its place on the geological 

 scale. Thanks to investigations ably carried out at Hoxne, in 

 Suffolk, and at Hitchin, in Hertfordshire, by Mr. Clement Keid, 

 under the auspices of this association and of the Royal Society, we 

 know that the implement-bearing beds at those places undoubtedly 

 belong to a time subsequent to the deposit of the great chalky 

 bowlder clay of the eastern counties of England. It is, of course, 

 self-evident that this vast deposit, in whatever manner it may have 

 been formed, could not for centuries after its deposition was com- 

 plete have presented a surface inhabitable by man. Moreover, at a 

 distance but little farther north beds exist which also, though at a 

 somewhat later date, were apparently formed under glacial condi- 

 tions. At Hoxne the interval between the deposit of the bowlder 

 clay and of the implement-bearing beds is distinctly proved to have 

 witnessed at least two noteworthy changes in climate. The beds 

 immediately reposing on the clay are characterized by the presence 



