218 Dr. Irving — Surface-Changes in London Basin. 
gravel, irregularly bedded with occasional puckers; no trace of 
oblique lamination seen, strong dip to the north; beds here and 
there of pebbles and discoloured angular flints, which are strewn 
through every portion of the sand, thin clay partings (occasionally 
an inch thick) with intenser colour in the sands just above them.” 
These sandy portions of the gravel passed southwards into a more 
gravelly mass, with little or no sand; and ona second visit to the 
place I found that a deep cutting had been made from the face of 
the pit down into the London Clay. Here the angular gravel was 
seen in a fresh open daylight section, running beneath the more 
sandy portions of the mass, and lying upon an eroded surface of 
London Clay, well down in which was a layer of flint-pebbles 
dipping about south-east at an angle of 5°. It is quite easy to see 
how the quondam higher Bagshot terrain immediately to the south 
had, in the denudation of the country, furnished the materials: 
_ (1) the flinty material from its surface to form the more gravelly 
part of the deposit; (2) the sandy material, which (with some 
admixture of flinty stuff) had been washed down over it, the whole 
mass being nothing more than a talus-deposit against the flank of a 
hill, which has since disappeared. But the interest of the section 
does not end here, for it afforded evidence of glaciation and of the 
pre-Glacial age of this secondary gravel, as may be seen from the 
following note made on the spot :—“‘On the worn and eroded surface 
of the above lies a glacial deposit (in fact a ‘Boulder-clay’) with a 
maximum thickness of 5 feet, full of pebbles and angular flint 
fragments, generally standing on end.” In my paper of 1890 on 
the plateau-gravels' I have referred to this as ‘‘an unstratified 
Boulder-clay, with pebbles standing erect in it, lying upon an older 
angular and sandy gravel, which lies upon an eroded surface of the 
London Clay.” 
A similar deposit occurs at Kintbury, near Newbury, for which 
J am indebted to Mr. F. J. Bennett of the Geological Survey, who 
about the same date made the following entry in my note-book :— 
Bie. 1. 
<_< SSE OSS 
x 0 0 0 Caeit a 
(() 0 0 aS 
B a0. 9 Vea S| 2 
0 Co 
= Spl cs out 
Cc Se = is a 
2 2 2 os 2S 
A. Pebbles in sandy matrix, clayey here and there, pebbles mostly vertical. 
B. Pebbles in grey stiif pipe-clay, pebbles also vertical. 
C. Pebbles in soft Bagshot sand, mostly horizontal. 
In the case at Kintbury, as in that described above north of 
Bracknell, it is easy to understand how ordinary currents would lay 
1 Q.J.G.S. vol. xlvi. p. 562. 
