DAKYNS : LOWER CARBONIFEROUS ROCKS IN YORKSHIRE. 361 
which, in Weusleydale, we identified on purely strategraphical 
grounds as the equivalent of the Red Scar Grit. 
This gi'it is the middle grit of Phillip's mentioned on page 65 of 
his Geology of the Mountain Limestone district, where he is quite 
right in saying that " it corresponds in position with the top grit of 
Penhill." 
In Coverdale the upper part of the gTit is a white siliceous rock 
with rootlets, like ganister. Similar ganisterlike rocks with 
Stigmaria also occur higher in the series. The frequent occurrence 
of ganister above the Red Scar Grit is important, and it is worthy of 
note that even as far south as Derbyshire ganister beds are apt to 
occur about this horizon, i.e., over the Kinderscout grit. In Cover- 
dale these ganister beds begin to be very numerous and characteristic 
of the beds. 
The lowest millstone grit is at its outcrop throughout Wharfe- 
dale a coarse and massive grit ; but Mr. Eddy tells me that in 
following the lead veins eastward in the Bearing grit the rock was 
found to degenerate into a mass of sandy shales and flags. At the 
head of Coverdale these lowest grits are in full force ; but they 
rapidly deteriorate down dale into a mass of sandy shales and thin 
poor sandstones. This change sets in immediately east of Crab 
Gill. A similar change in character takes place as one follows the 
grits down Walden. 
I have given above a brief sketch of the chief changes which the 
Lower Carboniferous Rocks of Yorkshire undergo from south to north. 
These may be summed up as follows : — 
1. The simple fourfold division of the millstone grit prevalent in 
Derbyshire ceases to be applicable northward, owing to the 
setting in of several fresh beds of sandstone. 
2. The Yoredale type of beds can hardly be said to exist south of 
Kettlewell. From Grassington northwards the Carboniferous 
Limestone becomes split up by beds of sandstone and shale ; 
and north of Kettlewell important rocks, to wit, the Underset 
and Main Limestones set in, so that finally we have in Yoredale 
the well-known type of beds that goes by that name. 
3. In the southern part of its course the Main Limestone is imme- 
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