32 
LAMPLUGH: GLACIAL SECTIONS. 
in some cases, to incipient concretionary action. In the sand near 
C, Fig". I , hardened root-like tubes of cemented sand, crossing 
the bedding, were at one time brought out by weathering ; and 
these I looked upon as being caused by the percolation of water 
which had passed through the chalky gravel above, and so 
became charged with lime. It may be that concretionary action 
may be set up by the same agent, though in a few cases the 
crumplings look very like contortions. I give an enlarged sec- 
tion of a case which seems to be concretionary (3). 
The surfaces of the clayey layers often exhibit pittings and 
other markings, which deserve closer study than I have yet been 
able to bestow.* 
The division between this series and the underlying gravel is 
generally abrupt, but in one or two places where the gravel is 
thick and sandy there is a clear passage between them. 
Here and there streaks and pockets of -gravel appear amongst 
the sand and clay, and in one or two places (as at E, but chiefly to 
the south of my section), the beds become charged with gravel 
from top to bottom. Three years ago a large travelled block was 
to be seenf imbedded in the lower part of this division, a few 
hundred yards south of Fig. 2, but this is the only recorded case 
of the kind. I have found no organic remains either in the sand 
or clay. 
The Lower Gravel ('2b J. This is a rough drift gravel, 
chiefly composed of pebbles and boulders washed out of the boul- 
der-clay ; but in some places it also contains in its upper part 
many chalk pebbles. An occasional shell -crumb may be found in 
it J — no more than might have been derived from the boulder- clay 
* At first 1 was di&posed to regard all these markings as rain pittings, 
but on one surface I examined, the pittings were arranged in definite groups 
of four, so that unless in the rainy days which followed the break-up of 
the ice, such things as symmetrical showers occasionally fell, the markings 
must be due to some other cause. 
t Recorded by J. R. Dakyns, supra cit. 
