466 
Geology of Norfolk. 
of the surface. But for this warp the Happing hundred wouUl 
have consisted of as barren sand as any in the county. It is there 
often 4 or 5* feet deep, while on the higher portions of Norfolk 
its depth is less than 6 inches. Soils of the latter description, 
Avhether loam or clay, are called by the farmer thin-skinned. 
This warp differs more or less from the subsoil on which it 
rests. On sands it contains a greater mixture of argillaceous 
matter producing a sandy loam of different degrees of adhesive- 
ness, on clay it contains an intermixture of sand producing a clay 
loam, or at any rate, clays less adhesive than those of the subsoil. 
The greatest height to which this deposit extends has yet to be 
determined. In Norfolk it has been spread, however thinly, over 
the highest parts of the county. The situations in which it is 
wanting are those which, from the form of the surface, would 
have been swept by currents instead of the water being allowed 
to stagnate over them, and to deposit its sediment. On steep 
escarpments it is almost wholly wanting, and in such situations 
the subjacent strata, whether gravel, sand, or clay, of the drift, or 
any member of the regular strata, exert their full influence on the 
characters of the soil. The following sections will illustrate the 
varying depths of this deposit dependent on the form of the 
ground. 
No. IV. represents the head of a valley about a quarter of a 
mile wide, excavated in the drift. The intensity of the surface- 
line denotes the varying depth of the warp or surface-soil. 
The warp is less than a loot deep on the summit of the plateau, 
wanting on the steep sides, and from a foot to 1 8 inches deep in 
the bottom of the valley. 
No. V. represents the valley when its width has increased to 
half a mile, and its sides, instead of being steep, have a gradual 
slope. 
In such cases there is a gradual increase in the depth of the 
warp from the summit of the plateau to the bottom of the valley, 
where it is from 18 inches to 2 feet deep. 
As the valley expands in the lower part of its course, Section 
VI., a warp is found in its bottom, varying in depth from 2 to 4 
or 5 feet, and gradually thinning off up the sloping sides. 
Even on the summit of the hills which bound the lower part 
* The analysis !)y Dr. Playfair, published iu a recent number of this 
Journal, of the soil of a field near Sutton, which produced eleven quar- 
ters of wheat to the acre in 1844, contanis nothing to indicate any extra- 
ordinary feitility. Soils, liowever, which yield to analysis only a small 
proportion of those ingredients essential to the growth of our cultivated 
plants, become highly productive when of great depth ; and this is the 
case not only with that under consideration, but with most of the very 
fertile land of the Happing hundred. 
