176 
GENERAL VIEWS. 
ready shewn that the area of the upper or Cara limestones of the Yoredale 
series is bounded on the south-east, by a line from Lancaster to Ryeloaf, 
there turning to pass under Great Whernside and along the eastern side 
of Coverdale. If another line be drawn from Great Whernside through 
Cam fell to Bow fell, it will divide the area of Cam limestone into two 
unequal parts ; in all the northern parts both the main and underset 
limestones belonging to this group are developed, but on the south of 
the line there is only one of these limestones, (except in a narrow tract 
running out through Widdale fell to Wharnside.) The point of inter- 
section of these two lines (under Great Whernside) is for this and other 
reasons often referred to in the following inquiries. 
The lower limestone attains its greatest thickness in the region be- 
tween Wharfedale and Ribblesdale : it is probably not less than 1000 
feet thick in the vicinity of Ivettlewell and Arncliffe. Under Inglebo- 
rough and Penyghent it is from 400 to 600 feet thick, and along the 
Penine chain from Kirby Stephen northwards a less thickness may be 
assigned to it. North of the line from Kettlewell to Bar fell the lower 
limestone becomes divided by beds of grit, shale, and coal, which 
augment continually northwards, so as at last to change altogether its 
character. In the Diagram, No. 24, this is attempted to be shewn in 
a peculiar manner. G G G being the general basis of grauwacke, and 
L L L a continuous circle representing the upper surface of the lower 
limestone, the thickness of this limestone in any direction, north, south, 
east, west, &c., is supposed proportionate to the interval between the 
two circles. In the direction of Kettlewell this is taken at 1000, in 
the direction of Bar fell 400. The interpolations of slate, grit, &c., are 
slightly marked in the northward direction, because the diagram is 
intended to apply only to the area between the Craven fault and the 
vale of the Greta. 
2 he Yoredale rocks exhibit within this area far greater variations : 
under Great Whernside they are reduced to about 300 feet : and this 
is almost wholly limestone belonging to the lower part of the group 
and thicker than usual : in the direction of Fountains fell, these lime- 
