Vol. 69.] PALEOZOIC ROCKS OF THE CAUTLEY DISTRICT. 11 



B. The Silurian Strata. 



Stockdale Shales. — In a paper on these beds by the late 

 Prof. Alleyne Nicholson and myself, a limestone 6 inches thick was 

 described as occurring at the base of these shales in Backside Beck. 

 There the Ashgill Shales are seen immediately below it ; we have 

 now found fossils in the limstone itself, and they are : — 



Encrinurus punctatus var. arenaceus \ Lept&na cf. quinquecostata. 



Man- & Nich. \ 

 Cheirurus bimucronatus Mnrch. var. 

 Phacops mucronatus. 



Orchis, two spp. 

 Strophomena, two spp. 

 Hyolithes. 



In the note communicated by Mr. Fearnsides and myself to the 

 British Association at Sheffield in 1910, it was stated that an im- 

 portant section of the Skelgill beds of the Stockdale Shales occurs 

 in Watley Gill. Of this I propose to give some further details. 



The basal limestone just noticed is here seen badly exposed on 

 both banks immediately above the Ashgill Shales. From it we 

 obtained : — 



Cyphaspis cf. rastritum Tornq. Phacops mucronatus. 



Acidaspis. Hyolithes. 



Above it are the shales of the DimorpJiograptus Zone with badly- 

 preserved graptolites, which, however, are sufficiently determinable 

 to indicate the zone. This is succeeded by the shales of the 

 Monograptus-fimbriatus Zone with that fossil, M. cyperoides Tornq., 

 and Diplograptns mutabilis Elles & Wood ? 



Above this come the hard mudstones of the Encrinurus Zone, 

 followed by the shales of the Monograptus-argentem Zone. The 

 latter is much crushed, but a little thinner than in the Lake 

 District. It contains the ' green streak,' also slightly thinner 

 than in that district. 



The fossils obtained from this zone are : — 



Monograptus argenteus Nich. 



M. leptotheca Lapw. 



M. convolutus His. 



M. nicoli Harkn. 



M. limatulus Tornq. 



M. communis Lapw. 



Monograplus gregai ius Lapw. ? 

 Basiriles hybrid us Lapw. 

 Climacograptus hughesi Nich. 

 Diplograptus sinuatus Nich. 

 Diplograptus belluhis Tornq. 



It is succeeded by the Phacops-glaber Zone, from which my son 

 obtained a tail of that form ; and above the beds of that zone are 

 the shales of the Monograptus-convolutus Zone, from which we 

 extracted the index-species and some of its usual accompaniments. 

 A fault here brings up the Dimorpliograptvs Beds once more, and 

 above this there is no further exposure in the gill. 



In the south-eastern dome the basal limestone of the Stockdale 

 Shales occurs in Birks-Wood Gill, a little distance above the road. 

 It here resembles the same limestone as seen in the Lake District, 

 and contains brachiopods ; but no specimens sufficiently perfect for 

 determination have been found. 



