66 Reviews: Whitaker— Geology of London, &c. 
its microscopic rhizopods, &c. are now tabulated,) it has a large 
chapter in this Memoir. 4. Of the Bagshot Series—the equivalent 
of the great Nummulitic Series of Europe, Asia, and North Africa— 
only the lower member (near Windsor and as outliers at Hamp- 
stead and Highgate) is shown in this Sheet; the great typical mass 
occurring in the neighbouring ‘ Sheet 8’ (not yet deseribed).—III. 
As old portions of the Post-Pliocene Series, and as ‘ Drifts of the 
Higher Levels,’ Mr. Whitaker notices the Boulder-clay, his ‘Clay- 
with-flints,’ the High-level* Brickearth, and High-level Gravel, 
both the pebbly and the angular. Here also he notices the ‘ Grey- 
wethers’ and ‘ Pudding-stones,’ that lie about the surface. As later 
Post-Pliocene deposits, the Valley-gravel (with flint-implements) 
and its Brickearth, and the recent Alluvium, complete the list. 
Throughout these descriptions the Author has carefully referred 
to, and fully quoted, Mr. Prestwich’s researches on the Tertiary and 
Post-Tertiary deposits (indeed, the Geological Surveyors have 
accepted, with due acknowledgment, Mr. Prestwich’s maps and 
sections as a basis for their own work in detail); and he evidently 
feels a pleasure in finishing the lines and filling in the tints of the 
masterly sketches of the ‘London Tertiaries,’ the ‘ Drift,’ and the 
‘Flint-implement-bearing Gravels, that Mr. Prestwich has set 
before Geologists. 
The ‘Form of the Ground,’ some very suggestive remarks on the 
‘River-valleys,’ and notes on ‘ Disturbances,’ follow. There are 
also three Appendices ;—two on Well-sections,t carefully tabulated ; 
and one on the likelihood of there being an underground ridge of 
older rocks { along the Valley of the Thames, as hinted at by 
De la Beche, well described (though unseen) by Godwin-Austen, 
and proved by Prestwich; and with this Mr. Whitaker gives the 
very instructive diagram here copied, which is itself equal to a 
chapter on the geological structure of the South-east of England, 
showing in detail what Mr. E. Hull’s sketch-diagram (in his ‘ Coal- 
fields,’ 2nd edit., p. 258) boldly indicates in a general manner. 
Seventeen woodcuts, for the most part indifferently printed, illus- 
trate the terraces of gravel near Maidenhead,—characteristic pit- 
sections (some, as Brockwell Hall Brickyard, not previously noticed), 
—and sections across the country, showing form of ground, disloca- 
tions, and other features, as at Windsor, Bushey, Lane End, Benneti’s 
End, and elsewhere. A good Index of Places adds value to the work. 
The Author throughout has evidently had a sharp eye for the 
Economics of Geology, such as Brickmaking, Pottery, Soils, Water- 
* Mr. Whitaker applies the words ‘ High-level Gravel’ to that on the plateaux, 
and ‘Low-level Gravel’ to that of the valleys and so often left im terraces. This 
appears more correct than terming the highest of the Terrace-gravels ‘ High- 
level, and leaving the Plateau-gravel higher still. 
+ That of Colney Hatch appears to have been left out by mischance. Mr. 
Whitaker expresses a wish to be informed of any new sections and well-diggings. 
{ We have seen the specimen of Lower Carboniferous Posidonomya that was 
brought up by the borer from these old rocks at Harwich, mentioned at p. 252 of 
the Geol. Soc. Journal, vol. xiv. 
