﻿58 ME. T. F. SIBLY OX THE FArXAL SCCCESSIOX IX THE i^Feb. I908, 



exposure of D^. Thinly-bedded limestones with strong chert are 

 here confonnablv succeeded by a series of alternating limestones 

 and black shales, with some hard calcareous bands in the latter. 

 Shales become predominant in the uppermost part of the section, 

 but corals and bracbiopods typical of D. occur throughout, and the 

 true Pendleside Series is not reached. Detailed measurements of 

 this section are given in the Geological-Survey Memoir." 



(ii) Ashford. 



Dg has a thick development at Ashford. 1 mile south of the 

 Longstone section. In the • Black-Marble Quarry " at this village, 

 thinly-bedded black limestones, with shaly partings and abundant 

 chert, contain a rich D^ fauna. At least 150 feet of limestones 

 must overlie these beds. The junction with the Pendleside Shales 

 is not exposed in the vicinity. 



(iii) Matlock Bridge. 



In Cawdor Quarry. Matlock Bridge, the thinly-bedded cherty 

 limestones contain a typical D^ fauna. The chertj' series is here 

 probably not more than 30 feet thick, being thinner than in 

 other parts of the Matlock district. The junction of tbe cherty 

 limestones with the Pendleside Shales is not seen. 



(iv) Matlock Bath and Cromford. 



In the railway-cutting south of Matlock-Bath Station, at the 

 entrance to AVillersley Tunnel, the Pendleside Shales are seen 

 resting conformably on the cherty limestones. The uppermost 

 beds of the latter contain a D, fauna, but the subzoue is not well- 

 developed. The junction is here very sharp, with no development 

 of passage-beds. 



At the southern end of the same tunnel, at Cromford Station, a 

 small exposure shows a more gradual passage into the "Pendleside 

 Shales. The D^ fauna is well represeuted in the limestone-and- 

 shale series at the base of the section. In the upper part of the 

 section, the black shales contain Posidonomya membra nacea (!).' 



( B ) Sections in the Southern Part of the Area. 



The Ci/athcuvonia-suhzone probably attains its maximum de- 

 velopment in the southern part of the area. Certainly, the finest 



^ ' Geolcgy of tbe Carboniferous Limestone, &.C., of ^orth Derbyshire ' 

 2nd ed. (18j>7) p. 19 ('section showing tbe junction of the Yoredale Beds 

 and the Mountain Limestone at the east end of Mousal Dale Tunnel '). 



- These two sections are briefly described in the • Summary of Prosrress of 

 the Geological Survey for 1904 ' 1\KJ5. pp. 9 & 10, where the following additional 

 fossils are recorded from the shales at Cromford Station : — Posidonidla, 

 rterhtopecien popyro.ceiis, and G^i/phioceras PhUUpsi. 



