297 
upheaved and denuded. That it is a member of the Coal- 
measures cannot be doubted, beds of Shale and Coal lie 
above it which are exactly similar to those below. The 
whole series was sunk through in the Shireoaks Pit, and 
they may also be examined about a couple of miles south of 
Masborough Station on the Midland Railway. 
(4) GENERAL CONTOUR AND EXTENT OF THE PERMIAN 
FORMATION. 
The Permian Limestone extends in a narrow strip, rarely 
exceeding four or five miles in breadth, from Tanfield, north 
of Ripon, in a southerly direction to Tickhill and Harthill, on 
the boundary of the county with Lincoln and Nottingham- 
shire. Its western boundary forms generally a bold escarp- 
ment overlooking the Coal-measures of the southern half of 
the Riding and the Millstone Grits of the northern, whilst in 
an easterly direction the Limestone falls with a gentle dip of 
from 2° to 6^ under the Bunter Sandstone, mostly enveloped 
in the superficial deposits of detritus, which form the exten- 
sive and low-lying vale of the Ouse. The western boundary, 
which is the one with which this paper is concerned, rises to 
a height of 400 feet above the sea-level in the northern part 
of the Riding, dipping from the Gritstone moors of Kirkby- 
Malzeard and Pateley. In its progress southward this eleva- 
tion is reduced at Knaresborough 225 feet, rising again at 
Rigton to 350 feet ; and about 300 feet is the average height, 
until the promontories are reached on which Conisborough 
Castle and Roche Abbey are built. The Limestone at these 
places attains its greatest elevation of about 500 feet. As 
its exact boundaries will be tolerably well indicated in the 
following pages, they are not given here. 
From the abrupt and often precipitous termination of the 
Limestone, and the frequent occurrence of outlying masses 
along its western edge, there appears gi'eat probability that 
