PHYSICAL GEOGRAPHY 
Ifc‘8 
for its sparry accumulations which I ever saw. On its floor was a 
quantity of brownish mud, which might give rise to expectation of 
finding bones ; 1 believe no sufficient trials were made. Gowden Pot 
hole is the entrance to a prodigious long flexuous subterranean narrow 
cavern, in places filled by the river Nidd, which here takes a sub- 
terranean course for one or two miles according to the quantity of 
water, and in almost all parts of the cave the sound of its waters 
may be heard as they rush along the secret channels of the lime- 
stone rocks. 
Yoredale Rocks . — .The varied features imparted to the scenery of the 
dales of Yorkshire, Durham, and Aldstone moor, are in general similar, 
and remarkably contrasted with the simpler aspect of the subjacent 
thicker limestone floors. Of the latter broad surfaces and mighty 
cliffs, with frequent and deep clefts, chasms, and caves, are the typical 
character throughout England and Wales : but the Yoredale series 
of shales, gritstones, and limestones, presents in every hill variations 
of feature corresponding to these different terms of the series, and the 
effect of the whole combined is quite peculiar. Yet as, north of the 
Craven fault, the lower limestones continually subdivide themselves 
they assume in all the Penine chain from Brough northwards some- 
what of the surface features of the Yoredale rocks, and in the wide 
moors of the west of Northumberland present hardly any points of' 
constant difference. Where it exists complete, as in the head of 
Wensleydale, the Yoredale series admits of being exactly characterized 
in a drawing so that its parts may be again recognized in other situa- 
tions. For example take the profile of a mountain whose top is 
capped with millstone grit, and base rests on the lower scar lime- 
stone ; its whole slope being formed of Yoredale rocks 800 to 1000 
feet thick and the series complete. The profile will present the 
following leading features. At the top of the series, under the 
rounded or angular craggy top of millstone grit, and perhaps a small 
edge of chert or little limestone, the main or twelve fathom lime- 
stone will project into a bold perpendicular scar; below it will be 
a little concave or flat slope terminated by a second and less con- 
