THE 



GEOLOGICAL MAGAZINE 



VOLUME LIX. 



No. VII.— JULY, 1922. 



ORIGINAL ARTICLES. 



On a Freshwater Shale with Viviparus and Associated 

 Beds from the Base of the Carboniferous Rocks in 

 Ribblesdale, Yorkshire. 



By Professor E. J. Garwood, Sc.D., F.R.S. 

 (PLATE XIII.) 



THE specimens here described were obtained by the writer from 

 a pocket in the surface of the Silurian Slates about 200 yards 

 to the north of Gillet Brae, exposed during the preliminary 

 excavation for Mr. Delany's quarry (the Horton Lime Works) in 

 1889. The quarry is situated on the right bank of the Ribble, 

 opposite Horton village. The site of the exposure is now buried 

 under tip heaps and there is little chance of further sections being 

 ■exposed. 



As a detailed survey of the district recently undertaken by the 

 writer has revealed no beds of a similar character in West Yorkshire, 

 it may be of interest to put on record the details of the section at 

 the time it was exposed. 



Description op the Section. 



The deposits in question, which are of considerable interest owing 

 to the unique faunas they contain, consisted when they were exposed 

 in 1889, of two beds, each a few inches in thickness, occupying a 

 slight depression in the surface of the upturned Silurian Slates. 



These two beds are overlain by a tliin layer of ])lack calcareous 

 shale, containmg crushed specimens of Cyriina carbonaria, which 

 can still be seen at the base of the quarry. 



This shale forms a thin layer at the base of the massive limestone 

 of the Nematophyllum minus subzone, which, as a rule, forms the 

 lowest horizon in the Carboniferous deposits on either side of the 

 Ribble valley to the north of the Craveii Faults. It will be convenient 

 to refer to the two lower beds of the section as 

 the Viviparus Shale and 

 the Lamellibranch Limestone respectively. 



The diagram (Fig. 1) gives the general succession as seen in 1889. 

 The two beds, V and L of Fig. 1 did not form one continuous 

 deposit, but were sharply separated from one another both by their 

 lithological characters and by their fossil contents, the general 

 relation between the t^vo being evidently that of a non-sequence. 



VOL. LIX.— NO. VII. 19 



