198 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 12,
the gravels are considerably thinner. The surface of the clay all
over this plateau is said to be extremely uneven, like the waves of
a sea.
Sketch of the Surface-deposits on the surrounding High Lands.
I will now take a less detailed survey of the high lands that surround this Rugby plateau, and are separated from it by the valley of Rainsbrook on the south, and by the Avon and its tributaries on the north and east.
Barby hill, to the south of Rugby, is capped with marlstone. There are no sandbeds or deposits of clay with pebbles, that I can find ; the wells are fed by surface-drains alone.
At Kilsby, however, there is the same clay, with chalk pebbles, that has been already described, and large beds of sand. This is high ground, the level of the rails at the entrance to the tunnel being about 370 feet above the sea. The clay is very stiff, 30 feet thick, and rests on sand. One of the sand-beds at Kilsby is well known from the trouble it gave when the tunnel was being made. About 200 yards from the south end of the tunnel, clay 40 feet thick rests on sand, which is saturated with water, and extends to great distances on each side of the tunnel. It was with the greatest difficulty that the tunnel was constructed through and under it ; for the water seemed to be inexhaustible.
At Crick the gravel rests on Lias, and the same at Yelvertoft.
At Shawell is a well 70 or 80 feet deep, which passed in succession through gravel, clay with stones and chalk, and at the bottom reached a bed of sand in which water was found abundantly.
At Swinford the gravel is about 10 feet thick, and rests on compacted and cemented gravel.
At Catthorpe we find the same gravel, clay with chalk, and sand that we have already met with so often.
At Clifton the wells vary from 15 to 40 feet ; at Mr. Newall's house, on the brow of the hill looking towards Rugby, a well and boring were made which showed 12 feet of gravel, and 80 feet of clay with pebbles of chalk, sand, and finally Lias clay. The railway- cutting is here sufficiently deep just to enter the clay with chalk-pebbles. They are best seen in the drains on each side of the line. The pebbles are well striated. Pebbles of Oolite and Carboniferous limestone and grit are found in the sand here.
At Newton the gravel is thin, resting on clay with pebbles ; at 40 feet the sand is reached.
At Brownsover the sand resembles that at Hillmorton, and is 40 feet deep. Nearer the mill, on the slope of the hill, the well-sinker reports that he made a boring, preliminary to the building of a house there, in which he bored 60 feet through clay with pebbles, but that he reached no sand, and obtained no water.
At Churchover 6 feet of gravel rests on 36 feet of similar clay with pebbles.
At Voile's farm, near Coton House, a boring of 150 feet passed through a few feet of gravel and Lias clay to the limestone rock.
