21 
CLTTNCH CLAY and SHALE. 
Soil. — Colour , Brown, darker and bluer wet. 
Consistence , unabsorbent, adhesive, and tenacious clay ; dries in hard lumps ; cracks 
in dry summers. 
Subsoil. — Much the same as the Stratum, in some places yellowish ; deeper, gradually changing 
to blue. 
Excavations and Ditches, hold Water. 
Stratum, hard clay rising in lumps, called Clunch ; deeper in the Stratum, blacker and lami- 
nated, called Shale. 
Water, The remarks on water in the Oak-tree Clay are applicable to this Stratum. 
The best water in the clay vale district lies in gravel, or in the rocks beneath the clays. 
Clunch Clay forms the base of the hills which are surmounted by the rocks and sands before 
described, appearing chiefly, if not wholly on the escarpment side of those eminences, and in 
the lower grounds of the several wide vales adjoining. Where the last mentioned and the Port- 
land rock, and their accompanying sands also, become deficient, the absence of such partitions 
in these clays, which altogether form the broad district parallel to the chalk before-mentioned, 
renders the distinction between the thick clays and the Brickearth above them very difficult. 
And which of them keeps possession of the low surface, wherein they ought all to be found, 
must ultimately be determined by further and more accurate observations on these and other of 
their respective distinguishing characters. 
The Stratum of the Clunch Clay, and the other clay on the confines of the stony district, 
terminate in some parts of their course in rounded low hills, which are called knolls or knowls. 
A small hill by the Worcester road, two miles out of Oxford, and Lew-hill, near Bampton, 
are some of these. Other such occur between Malmsbury and Chippenham, and further west- 
ward along the courses of these Strata, through the vale of Blackmoor. 
The general course of these very thick Strata of clay, through the interior of England, may 
be known as the site of the broadest vales before enumerated, and likewise of the lowest land 
in the island, and of that most frequently subject to inundation ; but they also rise like other soft 
Strata, into hills of moderate elevation. 
The outcrop or basset edge of the thick Stratum of Clunch Clay, from its N. E„ course 
through Buckinghamshire, enters Bedfordshire, between Olney and Bedford, and is protruded 
on the heights, into the great bend of the river Ouse, between these two places. The extreme 
continuation of the Clunch northward, seems to form the summit of drainage, through the 
remainder of Bedfordshire, north of the Ouse, and so continues to form the boundary between 
Northampton and Huntingdonshires, into the fens below Peterborough, and continues north- 
ward through Lincolnshire, under and parallel to the low land. o 
