25 
CORNBRASH. 
Soil. — Colour , reddish brown, more remarkable on the outcrop of the upper, than of the lower 
part of the rock. 
Consistence , rather tenacious when wet ; but like other Stonebrash soils on the rubbly 
subsoil of a Limestone rock, it is kept loose enough for cultivation by the small 
rubble stones thickly strewed on the surface of its ploughed fields, but which 
disappear when laid down to pasture. In some fields these are mostly organized 
fossils. 
Subsoil, Rubble or roadstones, rather flat, and so little intermixed with soil or earth, as to be 
used on the roads as they are shovelled up from the quarries. 
Stratum, the same. The bluer, thicker, and larger stones in deep quarries are rarely more 
than six inches thick in the beds : outsides brown and earthy, darker and harder within. 
The rock generally grey or blue under its incumbent stratum of clay. 
Water, in the winter too commonly fills every crevice in the stratum of rock, the subsoil and 
soil ; dry in the summer. 
Excavations, hold water in winter, — not deep, — 'made for the use of the roads, to the extent 
of some acres, and if well levelled, resoiled, and drained, taking out the stone in some 
instances, rather improves than injures the land. 
In a distinct arrangement of British Geology into assemblages of Strata, which collectively 
form distinguishing features of the Earth’s surface, and each class described by an appropriate 
name, the Stratum under consideration must form the boundary of one of those important 
divisions. It is the decided limit of the Clay Vale District , and the commencement of the 
stony surface, which gradually rises to the Stonebrash Hills. It rarely ascends to the highest 
of those hills, but occurs more generally on the confines ofthelow ground formed by the incumbent 
Stratum of clay. As the hills of this stratum are not high, so its Tallies are not deep : in 
some parts they are merely slight undulations of surface, which correspond to similar undula- 
tions in the Stratum, and crossing its general course, produce many small springs and rivulets, 
frequently dry in the summer. 
Like some other Limestones, the Cornbrash forms small insular knolls, or caps of hills, on 
the sloping side of the great series of Stonebrash Hills, of which it forms a part. Such 
detached parts occur near Charterhouse Hinton, south of Bath. That of Addington, Wood- 
ford, and Wold Farm, north of the river Nen, in Northamptonshire, appears to be so. 
It is remarkable for regularly sloping planes on its surface, as near Witney, Campsfield 
near Woodstock, and near Bicester in Oxfordshire, and also near Peterborough. It is chiefly 
in arable, superior in quality to much of the similar soils of the Stonebrash Hills, and when 
otherwise appropriated to pasture, produces grass of a good quality. 
The Cornbrash, though altogether but a thin rock, has not its organized fossils equally 
diffused, or promiscuously distributed. The upper beds of stone which compose the rock. 
