1870. ] WILSON—RUGBY SURFACE-DEPOSITS. 197 
what seem to be detached, are seen in the gravel; but I have never 
been certain of a single case of detachment. Stones are found im- 
bedded in the upper and under surfaces of the clay, notably the 
latter; I have found no striated stones here. The drift is of the 
usual character—quartzose pebbles and grits, and flints, in ‘about 
equal quantities, and sand, which lies sometimes in patches. Some 
of the stones here are large, one or two feet in circumference. 
Continuing to skirt the plateau we come next to that arm of the 
hill which runs between the Lawford and Bilton roads. By the side 
of the road from Old Bilton to New Bilton is an excavation, in the 
upper part of which sand is worked, and in the lower clay. The 
sand caps the hill, and is of the usual character; it is overlain by 
a remarkable deposit about 5 feet thick where it is now exposed, 
consisting of marly clay, with pebbles very evenly interspersed 
through its whole thickness. The most frequent are chalk; and 
these are generally well striated. The clay is in some cases suffi- 
ciently mingled with sand to allow of the percolation of water; and 
in consequence the chalk is here in a state of powder. There is a 
block of syenite of considerable size lying on the surface there, and a 
still larger block, weighing several hundred pounds, of grit, smoothed 
and striated longitudinally. 
The clay with chalk pebbles is very partial on this hill, as far 
as I know; but the sand continues along the brow of the hill to 
Rugby. 
The Dunchurch-Road Pit, higher up the same side valley, and on 
the same side of it, offers a very instructive section. In March 
1869 there was exposed a face of undisturbed Lower Las clay, con- 
taining a few ammonites, &c.; on it rested a stiff brown clay con- 
taining many stones, but principally blocks of chalk. I obtained 
grit (sometimes in large blocks; one was 2 feet long and 1 foot 
9 inches broad and high), Oolitic blocks, Lias, many flints, and 
quartzite pebbles. The chalk is found in pieces of all weights, from 
1 ewt. down to dust, the particles of which can only be detected 
by a microscope. All the larger pebbles are grooved. 
The sand is slightly stratified, sugary, and contains grains of 
chalk universally. In some places Grmulel tag pieces of chalk can 
still be seen. Mr. Pike reports that 123 per cent of an average 
specimen consisted of carbonate of lime and sesquioxide of iron. 
Above the sand is the usual flinty and quartzose drift, here thin, 
but higher up the hill successively 6, 10, and 13 feet thick. The 
drift is entirely wanting a little lower down the slope. The surface 
of the Boulder-clay here is very uneven; of the Lias clay generally 
even. 
The next arm of the same plateau is that on which Bilton stands. 
This closely resembles the rest. At the vicarage at Bilton is 2 or 
3 feet of gravel and then 23 feet of sand, this being on the slope of 
the hill; at the top is 13 feet of gravel over clay. Near the Blue 
Boar, at Causton, and elsewhere in the neighbourhood, we meet with 
from 5 to 15 feet of gravel, resting on clay with pebbles and sand, 
and finally on Lias clay. Towards Frankton and Church Lawford 
. 
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