4 
On the Farming of Middlesex. 
Geological Features and Chabacter of the Soil. 
London g^ives its name to tte geological basin of which it 
may be said to form the centre. Most of the surface or subsoil 
of Middlesex consists of the clay known as the London Clay, 
which rests on the lower tertiary beds or the Plastic Clay- 
formation, whose upper surface is, as its name indicates, a 
tenacious clay, between which and the underlying chalk are 
beds of sand varying in thickness and in quality, some highly 
ferruginous, others of the purest silex, uncharged with any 
extraneous substance.. It is only in a small portion of the 
north-west corner, and a still smaller portion of the north-eastern 
corner of the county, that these strata form the surface ; the 
former being the escarpment of the tertiary strata immediately 
overlying the chalk, here exposed where it overhangs the River 
Coin, which a little lower down exchanges its bed in the 
chalk for the overlying London and Plastic Clays, and these it 
retains until it joins the Thames at Staines. The main river 
runs on the same bed till it passes the south-eastern outcrop of 
the chalk, at or about the boundary of the county below London. 
Though the lower tertiary beds, resting on the chalk, describe 
the geological condition of the county, there are other features 
which rule a great portion of its agricultural character and con- 
dition, especially that under arable cultivation. 
The higher elevations, such asHampstead, Highgate, Finchley, 
Harrow, Stanmore, and others, rising on an average 400 feet 
above the sea, are, on the ridges and crowns of the hills, 
capped with traces of the lower Bagshot beds or of the higher 
level gravel, and these, from their porous character, permit the 
percolation of water, which, being upheld by the subjacent im- 
pervious clay, is thrown out in springs, as at Hampstead and 
Highgate, where it is stored in reservoirs. Indeed, as all the 
higher levels are capped more or less by these beds, yielding 
water, here are the small perennial sources of the River Brent, 
Yedding, and other brooks. Moreover, the presence of water in 
these gravels has attracted a population, which is remarkably 
deficient in very many parts of the county, as, for example, the 
line of the Yedding Brook, between Harrow and Uxbridge, in 
many square miles where scarcely a habitation is to be found. 
The lack of other than surface-water is in some places relieved 
by artesian wells bored through the tertiary clays, and where the 
level permits, as at Uxbridge and Tottenham, they deliver their 
supply above the surface. The height to which water will rise 
from these sources has been calculated, and in general terms 
will accord with a line drawn from the known source of supply 
in the outcropping chalk to the north, to its natural outfall in 
