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were again rolled and scattered about over a more or less 
limited area, and intermingled with the other materials 
brought from a distance by the agency of ice. These 
pebbles of course must have been deposited in the New Red 
Sandstone, in the first instance at a much more ancient 
period, during the formation of the upper red marls, now 
almost entirely swept away, coeval with the equivalent 
Triassic bed in Devonshire ; and the inference would seem 
to be that this great lower Silurian formation, which is 
now so largely developed in Normandy, and which has 
left only a remnant in Cornwall, formerly occupied a much 
larger area in the south-west, and may also have had 
extensive ramifications towards the north-east. This is 
only another of the numerous examples of the almost 
total destruction of a once extensive formation, one of 
the broken links in the chain of geological evidence, which 
we often look for in vain, but which when found is of 
much interest and importance. In this drift are many old 
metamorphic rocks, probably derived from the north, and 
is therefore usually called northern drift, but although the 
fragments of the fossiliferous rocks are few, most of 
them seem to have travelled from all points of the 
compass, for it is reasonable to suppose that icebergs 
were often borne in different directions by adverse currents. 
The boulders are of all shapes, angular and rounded, the 
edges being often scratched and striated, as if they had 
undergone attrition by ice. It is rather remarkable that 
this glacial drift, in the more central portions of the 
county, contains comparatively few traces of the local 
Keuper Sandstone; for, as a general rule, most drifts of 
whatever age, contain a large admixture of the formation 
which prevails in the neighbourhood, as at Shipston, for 
example, on the southern borders of Warwickshire, where 
the Lias is predominant in the drift, and near Coventry 
