Geology of High Teesdale. 179 
of any vein of carbonate of lime in the neighbouring escarpments ; 
and the phenomena may be easily conceived to have arisen from 
a long trough-shaped depression in the upper surface of the 
fundamental rock. 
At all the last-mentioned places, the mineralogical pheno- 
mena are of no common interest. The beds of limestone externally 
resemble coarse masses of millstone-grit which has been bleached 
by the action of running water. When struck with the hammer, 
they generally shiver to pieces, and fall down in the form of 
large grains, which are externally dull and amorphous, but which 
easily split into transparent crystalline plates. No traces of organic 
remains are to be discovered in these large-grained masses of 
limestone, and in many of them, all colouring matter and im- 
purity seems to be completely driven off. They are all beau- 
tifully phosphorescent. I did not ascend from High Cronkley 
to the side of Mickle Fell, but I was informed, that the upper 
beds of the general section appear there with their usual external 
characters. 
9. At White Force, near the eastern extremity of Low Cronk- eras 
ley, a tributary mountain-stream is precipitated over one of the 
finest escarpments in Teesdale. The quantity of water was incon- 
siderable at the time I visited this spot; but when the stream is 
swollen by rain, the effect of the cascade must, in some respects, 
be superior both to High Force and Caldron Snout. The upper 
part of the precipice consists of a great tabular mass of prismatic 
trap, the whole thickness of which must be very considerable, 
as it extends some way above the precipice, and a perpendicular 
face of more than sixty feet is laid bare in a part of the natural 
section. Immediately behind the water-fall, the trap rests upon 
a single bed of granular limestone, more than thirty feet thick ; 
but the eastern escarpment, a few yards below, is much more 
complex. The trap is, on that side, supported by two beds of 
; Z2 
