82 UPPER CAMBRIAN (ORDOVICIAN). 



dale Series by Prof. Harkness and Dr. Nicholson ; they belong 

 properly to the Coniston Limestone Series, and may be classed 

 with the Dufton Shales. These Shales, as before mentioned, 

 overstep members of the Borrowdale Series, thus bearing out the 

 view that the Coniston Limestone and Borrowdale Series are 

 to some extent unconformable in the Lake District.' 



Dufton Shales. 



These beds consist of dark flaggy shales, sometimes having ashy 

 beds intercalated among them, and with bands of nodular lime- 

 stone near their base. They attain a thickness of 300 feet, and 

 may be seen at Swindale Beck, near Knock ; Pusgill and Dufton- 

 Town dykes, near Dufton ; Harthwaite Gill, near Keisley ; and at 

 the Smelt Mill, near Hilton. The fossils include Strophomeyia 

 expafisa, LeptcEfia sericea, Orthis vespertilio, Discina corona, CaJymejie 

 Blumenbachii, Triniideiis concejitrictis, Homalonoius bisidcatus, 

 Agnostiis, and Ilhtnus Boivmanni. In addition Holopea, BcUerophon 

 and OrtJioceras have been noted, as well as two species of Corals, 

 stems of Crinoids, etc. The shales are locally known as the 

 Swindale Shales, Pusgill Shales, etc. 



On a somewhat lower horizon at Style-End Grassing, between 

 Long Sleddale and Kentmere, there is a band of shales, separated 

 from the Coniston Limestone by some thickness of volcanic rocks, 

 etc. The fossils of these Style-End Grassing beds are of Bala 

 types, such as Calymeiie Blumenbachii, Orthis vcsptriilio, and Petraia 

 aquisulcata? 



CONISTON LIMESTONE. 



This formation, named by Sedgwick from Coniston in Lanca- 

 shire, consists of hard grey calcareous shales and slates, containing 

 nodules or thin bands of dark blue crystalline limestone of variable 

 character. In some places the beds of limestone, in others the 

 shales predominate. On the whole there is nowhere so great a 

 development of limestone as is met with in the Bala beds, with 

 which the Coniston Limestone is paralleled. The Coniston Lime- 

 stone (and shales) attain a thickness of about 200 feet. 



Among the fossils are Heliolites interstincta, Halysites catenulariiis, 

 Petraia {Strepttlasma ?) ccquisiilcata, Favosites fibrosa, Trinucleus seti- 

 cornis, Cheirurus juvenis, Sphcvrexochus, Lichas laxaius, IllcEuus Bow- 

 juaniii, I. Davisii, Phacops conophthahnus, and P. macroura (both of 

 which species have been taken to mark zones), Sirophomena anti- 

 qiiafa, S. depressa, Orthis calligrani7na, O. flabellulum, O. actonice, 

 O. vespertilio, LeptCEna sericea, Orthoceras vagans. 



While fossils are, as a rule, abundant, they are not often well 



1 W. T. Aveline, G. Mag. 1872, p. 441. 



- Harkness and Nicholson, Q. J. xxi. 248 ; xxii. 480 ; xxxiii. 461 ; Proc. Geol. 

 Assoc, iii. 109. 



