81 
Chain ; and the same kind of boulders might be traced 
nearly along the whole of the lower valley of the 
Tees. 
He did not offer these facts as new, but as proofs that 
the subsoil was often drifted in considerable parts, from a 
great distance, and that the connexion between agricul- 
ture and the primary objects of geology was less imme- 
diate than might be at first sight imagined. He did not 
make such statements with any view of discouraging 
their investigations ; far from it. He only wished to 
caution them against the seduction of hasty generaliza- 
tions, which often led to disappointment, and so tended 
to retard science. 
The conclusions to which these general remarks 
seemed to point, might be illustrated by an appeal to 
facts of a more specific kind. Take, for example, the 
carboniferous limestone in its range through Derbyshire, 
Yorkshire, and Cumberland, to the confines of Scotland. 
In one place they had associated with it, and partly 
derived from it, a soil of extreme fertility and well irri- 
gated ; in another, a soil deficient in quantity and unpro- 
ductive from want of water ; in a third, (for example, 
in parts of Westmorland and Cumberland,) a sandy 
and barren soil had been drifted over the limestone 
from the neighbouring sandstone formation. The same 
rocks give support, therefore, to soils of most con- 
trasted qualities. 
It was not, therefore, true that the agriculturist could 
in the first instance derive much help from the study of 
a geological map. It was only by minute details and 
local investigations, (like those just read,) that he could 
learn the nature and value of his subsoil. But this 
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