hind: carboniferous rocks of the PENNINE SYSTEM. 429 
Wharfe near Linton stepping stones, and in the beds seen in the 
brooks between Burnsall village and the grits of Thorpe Fell. North 
of the Wharfe I got Posidoniella l(Evis in shales near the bridge over 
Hebden Gill and the bank opposite St. Michael's Church, Linton. 
In shales in the riv^er Wharfe, near the stepping-stones at Linton, 
I got Posidonomya membranacea in abundance, with remains of 
Goniatites. It lias generally been taught that the knolls of lime- 
stone in Craven are the representatives of the Pendleside Limestone, 
in spite of tlie fact that the stratigraphical succession of the Thorpe, 
Cracoe. and Pendle-Clitheroe districts are identical, that the limestones 
of Clitheroe and Cracoe are exactly similar in composition, and both 
are altogether different from the Pendleside Limestone, and notwith- 
standing the fact that the faunas of the Clitheroe and Cracoe Lime- 
stones are identical and differ entirely from that of the Pendleside 
Limestone, and that the latter fauna is abundantly present in the 
shale series which immediately succeeds the limestone of the knolls. 
Nor are the knolls themselves on different horizons, but they belong 
to the same anticlinal fold cut into domes by small water courses 
and the sub-aerial action of water containing CO.2 in solution, and 
therefore not always weathered equally, by which I mean that 
different posts of limestone are to be seen on the diiTerent hills. 
Between Butterhaw and Hill Skelterton is a fairly large swallow 
hole, in the upper part of which is seen a section of shales enclosing 
a black limestone, dipping at an angle that I think quite sufficient to 
carry them over the white limestone, but if not, the true position 
may have been altered by the undermining wliich has occurred in 
the swallow. The black limestone is crammed with Posidonomya 
Becheri, Posidoniella Icm-is, and Glyphioceras reticulatum. 
The presence of the Pendleside Limestone is thus demonstrated 
above the white limestone of the knolls, and the closeness of the bed 
to the white limestone of the swallow also shows the rapid thinning 
away of the mass of shales, which, at Pendle Hill, separate the Pendle- 
side Limestone from the Clitheroe Limestone. This tliinning away 
of the Pendleside series is borne out by the presence on Simondseat 
of swallow holes in the Grit, which shows that the limestone is no 
great distance below the surface. North of Grassington and almost 
