194 WRECK OF EACH NEIGHBOURHOOD MIXED WITH THEM. 
the latter are less rolled and more angular than those which have 
come from the Continent: thus in the counties of Suffolk, Norfolk, 
Lincoln, and Yorkshire, the diluvium contains a large proportion of 
fragments of chalk and chalk-flints, which might have been derived 
from the immediately subjacent strata of chalk, or their continuation 
across the German Ocean by the Dogger Bank to Denmark; whilst 
in the counties of Durham and Northumberland there are no remains 
of chalk, but a similar admixture of the wreck of strata that compose 
the coal formation of these counties, with Scotch, Norwegian, and 
Swedish rocks. In the diluvium of the numerous valleys of York¬ 
shire, that unite to fall into the Humber, there is a similar admixture 
of the debris of strata composing the adjacent country, with rounded 
fragments of distant rocks ; and in the county of Durham I collected, 
within a few miles on the north of Darlington, pebbles of more than 
20 varieties of slate and greenstone rocks, that occur no where 
nearer than the Lake district of Cumberland. In the street at Dar¬ 
lington, at the north end of the town, is a large block of granite, of 
the same variety with those at Shap, near Penrith. Blocks of the 
same granite lie also in the valley of Stokesley, and in the bed of the 
Tees at Bernard Castle, and near the highest points of the pass of 
Stainmoor Forest. Similar blocks are found also on the elevated 
plain of Sedgefield, on the south-east of Durham. In all these places 
they are mixed with rolled masses of various kinds of green-stone, 
and porphyry. 
The nearest point from which these blocks and pebbles could pos¬ 
sibly have been derived is the Lake district of Cumberland; and the 
only place in England where this peculiar kind of granite occurs in 
