REVIEWS. 
119 
the results of which have been published during the past year in the Memoirs of 
British and Foreign Scientific Societies. 
On the '24th, papers on the Mutations of Level were read ; namely, on elevations 
and depressions of land on the eastern coast of Sicily, in Aberdeenshire, and in 
South Wales. 
EE V'lE WS. 
The Ground beneath us : its Geological Phases and Changes. By Joseph 
Peestwich, Esq., F.R.S., F.G.S. London ; Van Voorst. 1857. 
This truly excellent pamphlet, which made its appearance at the close of the last 
year, is the substance of three lectures delivered by the author at the Clapham 
AthenaBum, and contains much valuable matter relating to the London Tertiary 
and Drift deposits. It ought to be in the hands of every student interested in 
those later eras of the formation of our world, and the general progress of the 
science of Geology would be greatly facilitated if every district possessed as accu- 
rate and as intelligible a description as that given here of the London area. The 
author commences with the Post-Pleiocene period, and in his remarks, treats of 
the origin of the sub-angular flint-gravel ; of the sources whence the materials of 
that curious deposit were derived, how and by what means they were accumulated 
in their present situations, and of the evidences by which its geological age is 
determined. The woodcuts throughout the pamphlet are in pure outline, in accord- 
ance with the elementary character of the work ; and the specimens of sub-angular 
flint, flint-pebble, and flints containing traces of various familiar fossils of the 
upper white chalk, have been appropriately selected for the illustration of this 
portion. 
The author afterwards passes to the organic remains of the Drift period, and 
gives an admirable sketch of that great mammalian era which preceded our own 
when the mammoth, rhinoceros, and hippopotamus, and herds of gigantic oxen 
and deer roamed in their wild freedom over our now busy and peaceful land, 
unmolested except by the carnivorous tigers, hyaenas, wolves, and bears that 
prowled through the forests or lurked in the caves. Figures are given of the teeth 
of mammoth, rhinoceros, and hysena, of the horns of deer and ox, and of several 
species of those delicate marsh-shells, Pupa, Succinea, &c., which are preserved in 
the same beds. 
The second lecture is devoted to the London Clay and its characteristic organic 
remains. 
The denudation of the Thames valley is well explained in the text, and by 
some clear diagrams and a section ; while the characters of the molluscs, reptiles, 
fish, and plants of the London clay period, and their affinities to recent forms, are 
carefully considered and well exemplified in the figures given of the chief typical 
species. 
The lower London Tertiaries form the staple of the last lecture, which is, 
perhaps, the most important of the three for the matter it contains and the manner 
in which that matter is communicated. 
The practical study of the Lower Tertiary deposits of the region around London 
is at all times difficult to the uninitiated inquirer, and these, more than any of 
the other groups of strata, require an able expositor in the field — so much is there 
which may be overlooked, and so much which may be mistaken. Independent, 
however, of the assistance given to the student by the well-selected specimens of 
