Reviews—The Geological Survey of England and Wales. 273 
to be distinguished from the Till of the limestone valleys of York- 
shire. In all the places mentioned it bears the unmistakable 
character of a ground-moraine accreted under the direct weight of 
glacier-ice. The familiar features of the Till need not be recapitu- 
lated here, but the author insists that its essential character is that 
of a rude pavement of glaciated débris, ground from the rocks over 
which the glaciers have passed, with its larger boulders firmly 
glaciated in situ on their upper sides in the direction of ice-move- 
ment, and with a tendency to the production of fluxion structure 
here and there in the matrix, due to the onward drag of the superin- 
cumbent ice. In mere indiscriminateness of composition (which is 
the character often most emphasised) the Till is not to be distinguished 
from Boulder-clays formed under berg- or raft-ice, such as the highest 
marine clays of the Norwegian coasts, which are stuck promiscuously 
through with boulders derived from the glaciers of the interior. 
But the glaciation of boulders zn situ the author finds to be a really 
crucial distinction; he readily detected this “ sériated-pavement ” 
character in the Tills of all the districts above mentioned except 
Leipzig and Berlin, where the Boulder-clays resemble the Upper 
Boulder-clay (Hessle Clay) of the eastern seaboard of England and 
Scotland, and in the sections examined by him contained no blocks 
large enough to take the strie. 
15%) Ja WW dB Jah WWASe 
—_—~—>_—_- 
J.—Tue GeroLtocicaL Survey or EnGLanp AND WALES. 
OME time has elapsed since we last noticed a series of the 
Geological Survey Memoirs (Grou. Mae. for 1886, p. 65), and 
in the mean time a number of additional Memoirs have been pub- 
lished, attention having been drawn to only one of these (Guot. 
Mac. 1888. p. 31). Much more detail is inserted in these Explana- 
tions of.the Survey Maps than was the custom in the earlier 
publications; but if on this account they afford somewhat heavier 
reading, they are also much more valuable for reference on questions 
both of scientific interest and of practical concern. Indeed the precise 
record of facts and a statement of the localities where particular 
information has been obtained, are always of great value to sub- 
sequent investigators, as well as to engineers and well-sinkers. We 
note also that the prices of these Memoirs are very moderate. 
In addition to a number of General Memoirs on particular districts 
or rocks, no less than 66 Memoirs explanatory of the Survey Maps 
have now been published. Nevertheless much remains to be done 
ere the whole country is described in such detail. Portions of 
Hampshire and Dorsetshire have not yet been ‘explained’ in Survey 
publications ; the Isle of Man and the Channel Islands have not 
at present been officially surveyed; while Cornwall and much of 
Devonshire, the South Wales Coal-field and the Old Red Sandstone 
area of Brecknock- Hereford- and Monmouth-shires offer tempting 
fields for future detailed surveys. Moreover, the Drift-deposits over 
DECADE III.—VOL. V.—NO. VI. 18 
