194 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 12,
the gravel varies much, from 6, feet upwards; and all the way to
Hillmorton the same remark is true. On the whole it deepens towards
Hillmorton ; but an inspection of the ponds shows that there
are many places where the clay nears the surface.
At Hillmorton we come upon the most interesting spot in the whole neighbourhood. The gravel along the upper road averages 14 or 15 feet, thinning out on the slopes on all sides. At the toll-gate, on the slope leading to Kilsby, it is 8 feet. At Mr. Darnell's, which is at the head of the little lateral valley leading to Low Morton, it is 13 feet. At the Hillmorton clay-pits it can be seen to thin out down the slope of the hill from 6 to 3 feet or less. In sinking Mr. Darnell's well, there was found below the gravel a stiff sandy soil, wet, with streaks of white and red clay, then a stiff blue clay containing chalk-pebbles, 3 or 4 feet in thickness, and finally blue Lias clay containing nodules of limestone. The largest of the chalk-pebbles was about 1-1/2 inch round. The well was sunk 42 feet, and the boring continued 62 feet.
The ground slopes on all sides down to the narrow valley in which Lowmorton stands ; the street that leads to Hillmorton occupies nearly the whole width of the valley. The gravel thins out down the slope, and entirely disappears just above the lower village ; the surface-soil there rests on undisturbed Lias clay. On the sides and bottom of the valley are very large accumulations of sand, which form perhaps the most striking feature in this neighbourhood.
On the left-hand side of the valley is a large sand-pit with a clay-pit just above it. In the upper pit flinty drift is seen to overlie interstratified sands and gravel-beds to a depth of about 10 feet. The lower sands are not distinguishable from the sands of the sand-pit, with which they are evidently continuous. There are here several small faults in the sand : I ascertained by excavation that they passed down into stiff reddish greasy clay that lies under the sand and over the Lias clay. Seams of the same clay are found in the upper part of the sand-pit. The sand has a thickness of at least 47 feet, and is thrown against a remarkably steep bank of Lias clay. This must have a slope of not less than 45°.
The Sand-pit forms an amphitheatre 47 feet in height. It is a sugary dirty sand containing about 5 per cent, of chalk and sesquioxide of iron, according to an analysis made by Mr. W. H. Pike in the School laboratory. The sand is stratified, and contains a few thin layers of black carbonaceous matter resembling coal. It contains a few small pebbles of flint and quartzite ; and in the streaks of fine clay are nodules which contain some lime and a few rolled specimens of Gryphoea incurva.
The sand skirts the whole northern edge of the plateau before spoken of, and is shown at the cutting on the Rugby and Lowmorton road. It extends about half a mile towards Rugby, thinning out up the slope, where the clay comes to the surface. At Low Morton itself the valley is filled in its lower part with sand, and the east as well as the west slopes have large sand-banks. In some places it is exposed, covered with clean flinty gravel. But it is best exhibited
