THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE III. VOL. iX. 



No. III.— MARCH, 1892. 



OK-IO-Zn^TJLIL, ^AuI^TIOLIES. 



I 



I. — The Coniston Limestone Series. 



By J. E. Mark, M.A., F.R.S., Sec.G.S. 



(PLATE III.) 



T has long been known that the Coniston Limestone Series of 

 the English Lake District and surrounding areas is separable 

 into minor divisions. As a knowledge of these will prove useful in 

 settling the question as to the exact relation between the Coniston 

 Limestone beds and the underlying rocks, no apology seems needed 

 for giving a detailed account of the rocks of this series. 



The literature of the subject is extensive, but we fortunately 

 possess an excellent bibliography of works referring to the geoloo-y 

 of the Lake District, in the appendix supplied by Mr. Whitaker to 

 the late Mr. Ward's Memoir on the Geology of the Northern Half 

 of the English Lake District. 



The main outcrop of the Coniston Limestone, as well known, is 

 situated in a line running across the southern half of the district 

 between Shap Wells and Millom, and here the series is succeeded 

 by the Stockdale shales, and underlain by different members of the 

 Borrodale Volcanic Series. Outlying patches occur in the Cross 

 Fell area, the Sedbergh and Ingleton districts, and probably also in 

 the extreme north of the Lake region. 



§ 1. Classification of the Beds. 



Leaving out of consideration the doubtful beds immediately suc- 

 ceeding the rhy elites of Melmerby (cf. Nicholson and Marr, Q.J.G.S. 

 vol. xlvii. p. 509), and which may possibly form the summit of the 

 Llandeilo Series, the strata which form the subject of this communi- 

 cation belong to the Bala or Caradoc Series, and representatives of 

 the whole of this period are probably present in the north of 

 England. They may be classified as follows : — 



fAshgill Group |Asligill.Shales,50feet 



° ^ i otaurocep/ialus Limestone, 5 feet. 



Coniston ?Applethwaite Beds, 100 feet. 



Limestone . ai„jj„i„ p^^,„^ I Conglomerate, 10 feet. 



Seeies. 1 Jsieddale Cxroup -^ g^j^^ End Beds, 50 feet, Avith Yarlside 



V Ehyolites above. 

 ^Roman Fell Group ... Corona Beds, 100 feet. 



The figures indicate only approximate average thicknesses. The 

 three groups are readily distinguishable by the characters of their 



DECADE III, VOL. IX. NO. III. 7 



