178 Causes of Fertility or Barrenness of Soils. 
like sand, they are still sufficiently open to allow of the air cir- 
culating through and warming them ; easy of cultivation, they 
are ploughed with two horses. The clay protects from drought ; 
the sand causes a high temperature. In some cases the sand is 
replaced by coarse gravel, a large quantity of iron being present ; 
such soils, where the proportion of clay is large, are stubborn, 
and if cultivated when moist bind together and form masses very 
difficult to bring to pieces. Root crops grow well, though not 
equal to those on the sandy loams, and if fed off on tlie ground 
the latter is apt to become poached during wet weather, and the 
crop of barley often suffijrs. On the whole we should give the 
preference to the sandy loams. 
The principal sandy soils in this country exist in the follow- 
ing districts : — In the South-east, forming portions of the Plastic 
Clay, commonly very poor and often resting on clay, wet ; seen 
in parts of Surrey, Middlesex, and Berkshire. — Soils of the Iron 
and Hastings sand beds, belonging to the Weal den formation ; 
very various in quality : where sand and iron occur without 
clay they are poor ; where the latter earth is present, of very fair 
quality. — The soils of the Upper and Lower Greensand, occurring 
in Surrey, Hampshire, and the southern portions of the Isle of 
Wight. This series includes some of the richest, as well as 
poorest, soils in England. The former are found resting on the 
upper beds, and occur at Farnham, Selbourn, and the Isle of Wight. 
The powers of such soils are most extraordinary, due probably 
to a proper admixture of sand, clay, and lime, and the presence 
of soluble silicates — that is, silica united with certain alkalies 
in such proportions as are slowly rendered soluble by the action 
of rain-water. These soils are peculiarly adapted to the growth 
of wheat and hops, and produce bulky root crops. The soils 
of the lower greensand are the very reverse, generally consisting 
of fine sand, iron, traces of the alkalies, and scarcely any clay ; 
they are light and very poor, in many districts unfit for cultivation. 
Large tracts are seen covered with gorse and heather ; when a 
little better, they are frequently planted with larch and Scotch 
fir for hop-poles. Occasionally in the valleys a better soil is 
found, but even there it is weak, producing wretched pasture and 
very uncertain crops. — Tlie Lower Greensand is seen in some 
parts of Surrey, especially the northern division, where it joins the 
Weald clay, forming a considerable range of hills, of which Leith 
is the highest point. — We pass on to the soils of the Old and 
New Red Sandstone developed in the Southern and Western coun- 
ties. Taken as a class they form deep rich soils, and when clay 
is present in considerable quantities the finest oak timber land 
we have. The above, with a few smaller districts situated on 
the Silurian and primary rocks, form the principal sandy soils 
