﻿Vol. 64.] CARBONIFEROUS LIMESTONE OF THE MIDLANB AREA. 59 



sections of passage-beds belonging to this subzone are to be found 

 in that district. The most extensive exposures are those afforded 

 by the cuttings on the Ashbourne & Buxton branch of the London 

 & North-Western Eailway, between Tissington and Alsop-en-le- 

 Dale Stations. The geology of these cuttings has been admirably 

 described by Mr. H. H. Arnold-Bemrose, in whose papers ^ detailed 

 measurements of all the sections will be found. 



(i) Sections on the railway between Tissington and Aisop- 

 en-le-Dale. 



(a) Tissington cutting." 



In this section, a series of alternating limestones and shales, 

 about 100 feet thick, overlies the bedded tuff; but the true 

 Pendleside Shales are not reached. Both lithologically and 

 palaeontologically this series constitutes a splendid development 

 of passage-beds. Thin bands of limestone, often argillaceous, and 

 generally cherty, alternate with thick and thin beds of black shale ; 

 and massive beds of shelly, crinoidal limestone are occasionally 

 intercalated. The limestones in this series contain an abundant 

 and tyj)ical D3 fauna of corals and brachiopods ; while the shales 

 contain lamellibranchs, including Pterinojpecten papyraceus^ Posi- 

 donomya Beclieri, and Posidoniella Icevis. A bed of black shale, 

 only a few feet above the base of the series, contains Pterinopecten 

 jiapyraceus in abundance. 



(h) Highway-Close Barn cutting and Crake-Low 

 cutting.^^ 



The sections in Highway-Close Barn cutting and in the northern 

 part of Crake-Low cutting show parts of the series exposed in 

 Tissington cutting. A comparison of these two sections illustrates 

 the rapid variation in the development of shale at this horizon. 

 In Crake-Low cutting the series overlying the tuff contains no 

 appreciable amount of shale, but in Highway-Close Barn cutting, 

 nearer Tissington, black shales are strongly developed at the 

 same level. 



(c) jS'ewton-Grange cutting. 



In Newton-Grange cutting the section exposes an anticline, and 

 a comparison of the succession in the eastern and western limbs of 



^ ' Geology of the Ashbourne & Buxton Bi-anch of the London & North- 

 Western Railway : Part I. Ashbourne to Crake Low ' Quart. Journ. Geol. 

 Soc. vol. Iv (1899) p. 224 ; and ' Part II. Crake Low to Parsley Hay ' ibid. 

 vol. lix (1908) p. 337. In the present partly-overgrown state of the embankments, 

 the structure of some sections, where the beds are greatly contorted, is by no 

 means easy to interpret ; and I have found the descriptions given in these 

 papers to be of great assistance in my investigations. 



■^ H. H. Arnold-Bemrose, Quart. Journ. Geol. Soc, vol. Iv (1899) pp. 226-29 & 

 pis. xvii-xviii. This section was independently desci-ibed by Dr. Wheelton Hind, 

 Trans. North Staffs. Field Club, vol. xxxii (1897-98) pp. 114-16 & pi. 



3 H. H. Arnold-Bemrose, Quart. Journ. Geol. Soc. vol. Iv (1899) pp. 229-30 & 

 pis. xvii- xviii. 



