20 Reviews—Prestwich on Valléy-Deposits. 
organic remains by which they are characterized. The more recent, 
and especially the surface-deposits, were, comparatively speaking, 
neglected ; and, though by the more far-seeing the existing opera- 
tions of nature were studied as throwing light upon the method of 
formation of ancient deposits, yet there appears to have been a sort 
of latent feeling that a patch of gravel on a common, or a brick-field 
on a hill-side, were subjects altogether too superficial for the re- 
searches of a geologist. Or if, even, by the finding of mammalian 
bones or testaceous remains in them, these deposits were obtruded 
upon his notice, they stood a fair chance of being referred either to 
the Noachian deluge cr to a wash of the sea over the land, or to 
some mysterious cataclysmic action. © 
Of late years, however, the extreme interest of the beds connecting 
the Tertiary Period with the existing state of things, and more 
especially those containing the remains of a fauna so closely allied 
to that of the present day as the Postpliocene, has been keenly felt, 
and much time has been devoted to their study by many of our 
leading Geologists, and particularly by the author of the present 
paper. The discovery of flint implements, wrought by the hand of 
man, in the gravels of the Valley of the Somme and elsewhere, 
which formed the subject of a memoir by Mr. Prestwich commu- 
nicated to the Royal Society in the spring of 1859, added no little 
zest to these researches, and has greatly multiplied the number 
of those engaged in pursuing them. It is needless to do more than 
allude to the numerous books, pamphlets, and papers which have 
been written on the subject of the Antiquity of Man, to show the 
general interest that has been taken in these discoveries; and we 
therefore proceed at once to call attention to some of the salient 
points of this last most valuable contribution of Mr. Prestwich, the 
title of which stands at the head of this notice, and which originally 
consisted of two separate communications to the Royal Society, 
though they are now incorporated together. 
The various drift-gravels which occur along river-valleys, or 
capping the hills at their sides, have been regarded by different 
writers, first, as of marine origin; secondly, as due to cataclysmic 
action ; and, thirdly, as of fluviatile origin ; and Mr. Prestwich, after 
briefly citing some of the authors who have assigned them to 
these different causes, and stating the difficulties he felt in referring 
the excavation of existing valleys to the operation of rivers upon their 
present scale, or to cataclysmic action, thus states his own views :— 
‘I could not admit the possibility of river-action, as it now exists, 
having in any length of time excavated the presert valleys and 
spread out the old alluvia; neither was it possible to admit purely 
cataclysmic action in cases where the evidence of contemporaneous 
old land-surfaces and of fluviatile beds were so common. But with 
river-action of greater intensity, and periodical floods imparting a 
torrential character to the rivers, the consequences of the joint 
operation are obtained, and the phenomena admit of more ready 
explanation.’ 
‘These views are based on a careful examination of a large number 
