2 



DR. J. E. MARR ON THE LOWER 



[March 1913, 



Some brief notes on the rocks by myself and Mr. W. G. Fearn- 

 sides were published in the Report of the British Association 

 (Sheffield) 1910, p. 603. 



It will be well to give here a table of the strata as developed in 

 the Cautley district : — 



f Bannisdale Slates. 

 f Lower Ludlow J Coniston Grits (in a re- 



Ordovician.. 



/"Salopian .. 



\ 

 I Valentian 



[ Wenlock 



|- Tarannon . . 

 L Llandovery 



stricted sense;. 

 Cold well Beds. 



Brathay Flags. 

 Stockdale Shales. 



r Ashgillian. 

 I Caradocian. 



A. The Ordovician Strata. 



A reference to the Geological Survey map shows that these strata 

 are developed in three elliptical patches in the form of an inverted L, 

 with a strip running southwards from the end of the north-westerly 

 mass. As these ellipses are denuded domes, the Caradocian rocks, 

 on the whole, form the central portions, and the Ashgillian beds 

 their peripheries ; but, as there is much folding and faulting, there 

 are naturally exceptions to this general statement. 



One of the most satisfactory exposures is developed in Backside 

 Beck, which cuts through the north-westerly dome in a general 

 north-and-south direction. As the south-eastern side of this dome 

 is faulted out, there is an ascending sequence as one proceeds up 

 stream. This section will constitute the type-section, and after- 

 wards other sections will be described, which are confirmatory of 

 the succession established in the beds of Backside Beck. 



No attempt will be made to estimate the thickness of the rocks. 

 They certainly include several hundreds of feet of strata. 



A very detailed account of the section is given in the Geological 

 ■Survey Memoir (pp. 20-26). Fig. 1 (p. 6) shows the subdivisions 

 which I propose to make. 



The lowest beds are blackish shales, with impure blue-black 

 limestones, which extend from the south-eastern end of the dome 

 for a considerable distance up stream. The exact junction of these 

 beds with those that succeed them has not been determined in this 

 beck ; but the lower beds extend at least as far as a point a few 

 yards south of a ruined footbridge mentioned in the Survej r Memoir. 

 This bridge is 350 yards south-south-west of Mountain-View Farm. 

 Up to a point near the footbridge the beds yielded a Caradocian 

 assemblage of fossils. The following have been obtained : — 



Trinuoleus seticomis His. ? (common). 

 Remopleurides sp. (rare). 

 Illcenus bowmanni Salt. ? 

 Cybele verrucosa Dalm. 



Calymene planimarginata Beed (com- 

 mon). 

 Orthis calligramma Dalm. 

 Plectambonites sericca Dalm. 



