680 



MR. J. E. MAER AND DR. H. A. NICHOLSON 



There is no doubt, both from the position of this bed and its 

 resemblance to the calcareous Atrypa-Jitxuosa band of Skelgill, that 

 this deposit represents that zone, in which, it will be remembered, 

 Climacograptus 7iormalis occurred. The peculiar mottled appearance 

 of the two deposits is strikingly similar. We propose, however, to 

 speak of this deposit in Erowgill as the Zone of Dijplogra^tus 

 acuminatus. 



Aa2. Above this zone we find one or two feet of greatly disturbed, 

 hard, black, mudstones, which we have little hesitation in referring 

 to the DimorpJiograptus-confertus zone ; but the fossils are so badly 

 preserved that we have not succeeded in extracting any which are 

 capable of exact determination. 



The disturbed character of the beds is due to their proximity to 

 the strike-fault, the fissure of which comes immediately against them, 

 and separates them from the overlying shales of the Middle Skelgill 

 series. In this stream also we are therefore unable to estimate the 

 thickness of the J)imorj)Jiograj)tus~confertus zone, or of the lowest 

 subdivision of the Middle Skelgill beds. 



At the rake itself a considerable thickness of the Middle Skelgill 

 beds is missing, and the shales of the convolutus-zone are the lowest 

 beds of this group which are seen. Some yards above the rake, the 

 beds Aa 3 of the M.-fimbrlatus zone are seen, much broken, but with 

 specimens of Monograptus Jimhriatus, IN^ich., beautifully preserved 

 in relief. The character of the beds is that of the representatives in 

 the typical section ; but as they are faulted above and below (the 

 main strike-fault passing below them), they present little of interest. 



The lowest beds of the Middle Skelgill series, with the exception 

 just noted, occur at a point some distance below the rake, and not 

 far above where the cross-fault brings the Coniston-Limestone series 

 against the Stockdale Shales. The section here is represented in 

 fig. 3. 



Fig. 3. — Section of Isoclinal, Broivgill. (Scale 12 feet to 1 inch.) 



lizult 



Bal 



Ac 4 



Abb 



The Lower Skelgill beds are seen occupying the same position as 

 at the rake, but only one foot of the shales which we refer to the 

 I)imor2)7iograptns-zone is found below the strike-fault. Another 



