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. 



RE YIE WS. 



The Ground beneath us : its Geological Phases and Changes. By Joseph 

 Prestwich, 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 

 Athenaeum, 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 Greology 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 hyaena, 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 



