DAVIS : ERRATIC BOULDERS. 
267 
extent with rounded hillocks left by glaciers which once extended 
from the hills far down into the plains. On the northern border 
of the Fault the scenery is grander and bolder. Immense white 
scars of Mountain Limestone rise tier above tier with intervening 
flat surfaces of weather-worn limestone " pavements," the cracks 
and fissures in which afford shelter and nourishment to a few hardy 
plants, — the only signs of life which are to be found. There is an 
unbroken thickness of 500 or 600 feet of the limestone, compact, 
somewhat prismatic in structure, and light grey in colour. It 
forms a great plateau entending beneath Ingleborough, Penyghent, 
Whernside, and the other high hills of the district. In the deep 
vallies at the foot of the hills at Ingleton, Clapham, Crummack, 
and Ribblesdale, the thick Scar Limestone is seen to rest on the 
upturned and contorted edges of the grits and slates of the Silurian 
system. Very fine sections shewing the junction of the two 
groups of strata may be seen at Thornton Force, in Kingsdale. in 
Crummack-dale, and under Monghton Fell, in Ribblesdale. In each 
case the Silurian rocks are folded into a series of anticlinals, the 
upper surfaces of which have been ground down to a nearly level 
plane before the limestone became deposited above them. 
Besides the great fault named above, there is a second im- 
portant fault branching from it near Clapham, which passes the 
foot of the escarpment at Xorber, along the valley between 
Monghton Fell and Feizer, and thence along the Stainforth Scars 
to Malham Tarn. This fault brings the limestone of Giggieswick 
Scar down to the level of the Silurian rocks of Monghton Fell in a 
deep valley extending westwards from Helwith Bridge in Ribbles- 
dale to Wharfe on the Austwick Beck, a tributary of the Wenning. 
A branch from the Austwick Beck draining this cross valley rises 
at a less distance than half-a-mile from the river Ribble, a very 
slight rise in the surface of the ground forming the water shed 
between the two streams. 
Norber is the southern extremity of a long promontory of the 
Mountain Limestone, extending from the base of that portion of 
Ingleborough called Simon's Fell. On its western flank are 
