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much so as to strike the attention, and already to indicate 
their former presence in great numbers on the surface, before 
the land was cleared. Some boulders, however, still remain 
on the surface, and an examination of a beck course cut 
through drift, will readily disclose them in the drift. 
When I first found these boulders, seeing they mostly 
occurred in the open space between the higher and lower 
dales, I connected them with the drift of the open country, 
which, south of the limestone escarpment of the Craven Fault, 
contains many Silurian Erratics. Even so, it was difficult to 
see how such boulders should have got so far east of any 
outcrop of Silurian strata. 
The ice emerging from Ribblesdale, at Settle, would have 
to bend sharply to the east, nearly at right angles to its 
course, on entering the low ground, to enable it to carry boul- 
ders to the Wharfe at Grassington. For I quite satisfied 
myself, that these boulders had not come direct over the Fells 
from the Silurian strata of Ribblesdale ; I felt sure of this, 
because I carefully examined the ground, and not a boulder 
of Silurian rock could I find any where on the Fells, though 
boulders of Millstone grit were met with. It was only when 
one got below, say, the 800 contour, and therefore, down to 
the level of the spread of drift forming the lowlands, that 
they were to be met with. There is, not only no apparent 
reason, why the Ribblesdale ice should make such a sharp 
and sudden bend out of its course eastward, but every reason 
against it, for the ice from the Fells east of the Wharfe 
above Grassington, would be pressing away west. However, 
it is not only in the open part of the Wharfe valley that the 
boulders are found, though they are or have been more plenti- 
ful there ; but north of the gorge through which the river 
flows, between Netherside and Grass Wood, Silurian boulders 
are found well within the limits of the upper dale. There 
are several, lying on the alluvial flat on the west bank of 
