152 
by the existence of comparatively soft matter. But the deDudation of 
the clilFs on a larger scale has frequently crossed the false bedding and 
oblique lamination, and even the more massive stratification, in a way 
indicating a cause much more powerful than any subaerial agency. 
In front of the cliffs, and more especially along the bottoms of the 
wider passages, where bare rock is accessible, it may often be seen that 
the sites of the rochs which have been carried away consist of as hard grit 
as that composing the sides of the passages — thus showing that the pas- 
sages did not result from the washing out of softer matter, but from the 
abstraction of solid grit by an agency propelled in particular directions. 
In many instances this agency would appear to have acted uphill along 
an inclined plane, and to have abstracted the rocks now missing by a 
revulsive effort, as sea-waves now act in narrow inlets on coasts. The 
infilling of the passages with the existing grit and loose stones must have 
occurred subsequently to the excavation of the passages, and was 
probably brought about partly by the action of the sea, and partly by 
the more recent action of rain. 
The Brimham Eocks. 
Near Brimham Hall, on the face of a slope, there are several very 
striking rocky projections consisting of laterally detached cliffs with 
tails graduating into the ground above (like skylight windows on the 
roof of a house), and perfectly detached and circum denuded stacks. 
In most places the general slope comes up to the base of the rocks, but 
where weathering has taken place the fallen grit or sand forms a small 
underlying ridge. On the side and at the base of one rocky projection, 
there are rounded stones, including a large boulder imbedded in grit. 
Near the base of the slope there are three stacks in close proximity. 
One of them about twenty-four feet, and another about fifteen feet high, 
are separated by a narrow passage with a hard rocky floor. On the west or 
overhanging fronts of both stacks a regular and apparently unweathered 
concavity looks as if it had been grOund out by a powerful agency, 
probably ice wielded by water. 
Nearly on a level with the valley at the base of the slope or escarp- 
ment, there is a striking stack of rock, about twenty -four feet high, with 
a concavity on its west side, and rounded as well as subangular stones 
beneath its undercut base. Some unknown cause seems to prevent the 
accumulation of fine grit or sand in such situations, and likewise the 
growth of grass. Some of the pebbles may have been gathered off the 
surrounding field and thrown in. They consist of a kind of quartzite, 
Permian limestone, and other rocks foreign to the spot, as well as grit. 
Under a smaller stack close by, pebbles of different rocks may be seen 
packed up in a recess. In some cases among these rocks, blown rain 
