200 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 12,
The valley near Hillmorton church is very singular in its character.
All round the church, and extending up and down the
valley for some distance, is a peat-bed, which is exposed in some of
the deep ditches. Underneath it is sand, so impregnated with water
as to be called a quicksand. It appears that not long ago all this
was a marsh ; for Dr. Bucknill, of Hillmorton Hall, informs me that
a sum of money was left to the parish to keep up a floating cause-way
over the marsh to the church, which stands on firm ground in
the middle of the valley. Sand overlies the peat at the bridge over
the canal near the church, just opposite the mouth of the narrow
valley with the sand-pits in which the village lies. The London and
North-western railway crosses a portion of the marsh ; and immense
quantities of ballast were thrown in to make a firm foundation ;
finally, I am informed, faggots were used as a foundation for the
embankment. Similar difficulties were met with in constructing the
canal. The excavations at the locks drained the sand, and the fall
of the neighbouring houses seemed imminent. These houses are
built in some cases on large slabs of concrete resting on the wet
sand.
I caused a boring to be made here near the New Inn. It gave : — peat 3 feet, clay 1 foot, sand 25 feet ; and it was impossible to proceed further. The sand was mixed with fine clay, and contained a good deal of lime, so that when dried it soon became perfectly hard. The microscope showed grains of chalk and of rolled quartzose sand. The bottom of this boring was 280 feet above the sea.
The next boring was made in a meadow belonging to Dr. Bucknill, called the Moors. It gave 2 feet peat, 13 feet wet sand, 3 feet gravel, and then sand, more and more clayey and stiff, passing from yellowish to grey until it became too stiff for boring at 53 feet. All this sand contained fine clay and particles of chalk, effervesced slowly but continuously with acids, and was entirely unlike Lias clay. A very few small stones were met with, but not preserved.
The next boring was on the left-hand side of the road from Rugby to Clifton, on the right bank, close to the stream. It passed through 6 feet of alluvial soil and clay, then a mass of vegetable matter, being the decayed vegetation of the old river-bed, and then reached sand similar to that higher up the stream at Hillmorton. Several stones, flints, grits, and quartzite were met with in this boring. The lower part yielded a considerable quantity of chalk lumps in the clay. This boring was persevered in till 57 feet were passed through, and then rock was reached, and some fragments of limestone brought up. The bottom of this boring was 227 feet above the level of the sea.
The last boring was lower down the stream, close to the planks on the left bank of the river. It passed through fine yellow clay for 7 feet, then stones and sand for an inch or two, and then undisturbed Lias clay, totally unlike the clays previously reached. The boring was continued for 20 feet through this, and then stopped. The surface of the Lias clay here is 274 feet above the sea.
The relations of these borings will be understood by reference to
