Farming of Dorsetshire. 
397 
Dr, Buckland speaks of travelling from Lyme Re^Is to Whitby 
in Yorkshire on the lias, and from Weymouth to the Humber 
without once leaving the Oxford clay — feats which one would 
have a difficulty in accomplishing now that modern geological 
science has drawn its cordons of greensand, and coral rag, and 
Kimmeridge clay around these positions. And yet even the 
present careful survey leaves our rjeocultural requirements still 
unsatisfied. It is with the rock only that the geologist cares to 
deal : it is in the soil upon that rock that the agriculturist has 
the chief concern. But the rocks and the soil above them are 
often of opposite characters, and then the geology of the former 
is useful only in connexion with what may be termed the geo- 
culture of the latter. The depth of that soil, when composed of 
drift or erratic tertiaries, often exceeds the greatest extent to 
which for the purposes of agriculture we penetrate. " When 
they are only 2 feet thick, they constitute in many cases both 
soil and subsoil. When the depth extends to 7 feet, it is 
greater than the deepest drains of the deepest drainers. There 
are many places in which these deposits are several hundreds of 
feet thick, and there the sub-strata can have no agricultural 
value whatever, except from the fossil manures Avhich are fur- 
nished by their exposure within accessible distances. In our 
geological maps all these deposits are assumed as removed, and 
that rock is exhibited as constituting the surface, which would 
in that case be the surface." Here then the labours of the geo- 
logist cease, and the chemist must take up his task, and, by 
analyses of the soils lying on those rocks which it was the pro- 
vince of the geologist to name and explain, must show to the 
tiller of that soil its constituents and its properties. To this 
stage it is agreed by all agricultural writers no county has yet 
reached. I hope, therefore, to be excused for presenting the 
geology of Dorset, as Mr. Trimmer (from whose able paper I 
have taken the paragraph above) regards the geology of England 
— " rather as it ought to be, than as it is." 
In the ' Map of the Soil ' prefixed to Stevenson's Report, the 
surface is conveniently divided into chalk, stony chalk, sand, 
clay, (Sec. Now that we see it striped and ringed like a " taw " 
marble, with its belts of coral-rag, greensand, Kimmeridge clay, 
&c., we shall naturally be anxious to discover how far the surface 
soils correspond with the rocks on which they rest. Such an 
examination even of one county would be the labour of a life. 
We can only attempt to indicate a few features of difference. 
The tops of the chalk-hills are covered in many places with an 
accumulation of flint gravel, the remains of the denuded chalk, 
sometimes, as on the down west of Buckland Newton, to the 
depth of 20 feet. This is also the case in. the valleys, the 
VOL, XV, 2 D 
