On the StocMale Shales. 



519 



lie referred in some cases to rapture of the solid crast by the spread of 

 a vast mass of viscous matter lying beneath it (the faults being some- 

 times replaced above by monoclinal folds), he referred in conclusion 

 to the extent of the horizontal compression of the earth's superficial 

 crast which is seen to be associated with the elevation of mountain- 

 ranges, and called attention to some evidence that the thickening of 

 the strata caused thereby would be more considerable and general 

 than ordinarily supposed. 



3. " Notes on a Recent Discovery of Stigmaria ficoicles at Clayton, 

 Yorkshire." By Samuel A. Adamson, Esq., F.G.S. 



May 9.— W. T. Blanford, LL.D., F.R.S., President, in the Chair. 



The following communications were read : — 



1. " The Stockdale Shales." By J. E. Marr, Esq., M.A., Sec.G.S., 

 and Prof. H. A. Nicholson, M.D., D.Sc, F.G.S. 



The Stockdale Shales extend in an E.N.E.-W.S.W. direction 

 across the main part of the Lake District, parallel with the under- 

 lying Coniston Limestone Series and the overlying Coniston Flags, 

 with both of which they are conformable. They also occur in the 

 neighbourhood of Appleby, and in the Sedbergh district. They are 

 divisible into a lower group of black and dark grey and blue Grap- 

 tolite-bearing shales, interstratified with hard bluish-grey mud- 

 stones containing Trilobites and other organisms, and an upper 

 group of pale greenish-grey shales, with thin bands of dark Grap- 

 tolitic shales. The lower group (Skelgill Beds) are well seen in the 

 stream which runs past Skelgill Farm, and enters Windermere near 

 Low Wood ; while the upper group (Browgill Beds) occurs fully 

 developed in the Long Sleddale Valley, and its beds are very fossili- 

 ferous in Browgill. 



The authors divide these shales into a series of fossil-zones in the 

 following order : — 



r tt /B&2 



j | B# 2 zone of Monograptus crispus. 



Stockdale 

 Shales 



Browgill Beds ' 



1 



(Ac 5 



(Ac 4 



Upper ■{ Ac . 



turriculatus. 



Eastrites maximus. 



— Monograptus spinigerus. 



| Ac 2 Ampyx aloniensis. 



\ Ac 1 Monograptus Clingani band. 



( Ah 6 Barren band. 



| Ab 5 zone of Monograptus convolutus. 



| Middle \f h t P J} ao °P s $ l f cr - , 



)Ao o Monograptus argenteus. 



j Ab 2 Encrinurus pimctatus. 



yAb 1 Monograptus finibriat us. 



I jjower I ^ a " Dimorphograptus confertus. 



\ \ Aa 1 • — Diplograptus acuminatum & 



Atrypa flexuosa. 



Of these zones, the lowest varies, occurring as a thin limestone in 

 Skelgill, with Atrypa flexuosa, n. sp., and as Graptolitic shale at 

 Browgill with Diplograptus acwminatus, Mch. The others appear 



I 



Skelgill Beds \ 



