DEPOSITED IN WATER. 
59 
and shale series, all the beds which lie above the main or twelve fathom 
limestone, and which form the high heathy and boggy summits above 
the green slopes and scars of Yoredale limestone. 
It is only by a thorough knowledge of the country occupied 
by the millstone grit series of rocks, that they can be at all classified 
and reduced to a general system or type. 
The lowest pebbly gbit group known in the whole region 
south of the Tyne, is found every where almost in contact with the 
top of the limestone in the districts of Nidderdale, Greenhow hill, 
and Kettlewell. At Greenhow hill and Grassington its inferiority of 
position to the bold crag grits of JBrimham and Symon’s seat is most 
certain, and the measures which I. have taken in the upper and lower 
parts of Nidderdale, (above Lofthouse, at Brimham, Guise cliff, Darley, 
&c.) and about Greenhow, justify the assertion that at least seven 
hundred feet of shales, flagstones, and grit rocks, with one or more 
seams of coal and cherty beds intervene. Some of these grit rocks 
are coarse and occasionally pebbly, (above Pately bridge, and above 
Darley, Blubberhouses, &c.) 
One principal mass of the Brimham grits ranges E. N. E. and 
W. S. W., between the nearly parallel anticlinal elevations of Burn- 
sail and Bolton. Between the Rylstone and Flasby fells, a valley 
of the subjacent shale passes, and in this tract the thickness of the 
shales and grits between the Rylstone grit and the limestone is probably 
not less than that above recorded. 
The gritstone of the Strid near Barden tower, is probably the 
lower millstone grit ; I am now disposed to assign the same place 
to that which appears in the Washbourn river, at Thurscross ; it may 
also be traced above some considerable thickness of shale near Bolton 
bridge, especially under Gaukhall ridge, being every where eminently 
pebbly. It is not very distinct beneath the Flasby and Rylstone 
fells, toward the west. 
I 2 
