294 
A SKETCH uF THE GEOLOGY OF NIDDERDALE AND THE WASHBURN 
NORTH OF BLUBBERHOUSES. BY J. R. DAKYNS. 
Iii my former communications to this Society on the Carboni- 
ferous Rocks of the West Riding, I have said next to nothing about 
the geology of that part of the country east of Wharfedale, which 
drains into the Rivers Nidd and Washburn. I propose now to give 
a short sketch of the geology of this area ; but, in justice to Mr. J. 
Lucas, I must say that much of my knowledge of its geology, 
especially as regards the thickness of the beds, is derived from his 
patient and careful investigations. 
In the basin of the Washburn and in Nidderdale the Millstone 
Grit consists of the following members, which are lettered for con- 
venience of reference, as given in the annexed list. 
Average thickness 
in Feet. 
50 
45 
75 
30 
35 
50 
20 
75 
22 
97 
47 
77 
89 
Brimham Roc 
The Shell Bed 
A 
Upper Grit of 
Follifoot Ridge 
Shale 
Sandstone Jc 
Shale 
Sandstone h 
Shale 
Sandstone (f 
Shale 
Sandstone (f 
Shale 
Sandstone g- 
Shale 
Sandstone g x 
Shale 
Shell Bed/ 2 ... 
40 
Shale 
20 
Shell Bed/ 1 ... 
25 
Shale 
Sandstone c 
Shale 
= 85, but 
averaging 
33 
38 
45 
