J. E. Marr — The Coniston Limestone Series. 101 



'Calcareous shales. These shales, however, occur above the maiu 

 mass of the Swindale Limestone, and on a re-examination of our 

 •specimens, I am inclined to think that the lower and purer part of 

 the limestone of that beck, which contains large Orthocerata, like 

 those of Skelgill, along with Illcenus Boivmanni, may have to be 

 separated from the upper part which has the true Stauroceplialus 

 Limestone fauna, and correlated with the Keisley Limestone ; (a 

 similar limestone occurs below the Staurocephahis-heds of Billy's 

 Beck). If this be the case, the difficulty connected with the Keisley 

 Limestone would vanish. It would occur under two conditions in 

 the Cross Fell area, first, as a coarsely-crystalline very fossiliferous 

 Tock ; secondly, as a horny limestone in which the fossils are 

 ■mainly destroyed. Without offering here an explanation of the 

 frequent occurrence side by side of these two conditions of a 

 ■calcareous deposit, I may point out that they are very frequently 

 found in disturbed regions. I would cite in our own country the 

 Devonian rocks of the neighbourhood of Torquay, where the two 

 varieties are found in the same quarry, also the " Knolls" described 

 by Mr. Tiddeman (Report International Geological Congress of 

 1888, p. 319), which are found only amongst the rocks south of the 

 Craven Fault, where there are evidences of great disturbance, and 

 not in the nearly horizontal rocks to the north of the fault. 

 Abroad, a similar case occurs in Bohemia in the Konieprus Lime- 

 stone (F. f. 2). This limestone is generally a thin, horny, nearly 

 unfossiliferous limestone, but in the " Knoll " of Konieprus, and 

 Mnienian, we find the two varieties side by side. The same may be 

 said of the Leptmia Limestone and Klingkalk of Dalecarlia (cf. 

 Nathorst, Aft. ur Foren. i Stockholm Geol. Forhandl. No. 93, Bd. vii. 

 p. 559), and the Devonian Limestone of the Ardennes. 



It is not needful to discuss the origin of the nodular masses of 

 •crystalline limestone in this place. The cases cited show that the 

 occurrence of the horny and ciystalline conditions of the same 

 limestone in immediate proximity is a common event, and therefore, 

 whatsoever be the true explanation, there is nothing anomalous in 

 referring the Keisley Limestone to the Applethwaite Group, though, 

 ■as stated in the discussion on the paper by Prof. Nicholson and 

 myself on the Cross Fell area, we only refer the Keisley Limestone 

 and the Dufton Shales (which latter contain the ordinary Apple- 

 thwaite fauna) to the same subdivision of the Coniston Limestone 

 Series. If the suggestion thrown out above should prove to be 

 correct, a further division of the Applethwaite Group may be made 

 into a lower stage characterized by the ordinary Applethwaite fauna, 

 and an upper stage characterized by the fauna of Keisley and the 

 Chair of Kildare. This will probably be finally settled when the 

 Irish beds are re-examined, and in the meantime I include the 

 Keisley fossils and those of the other Applethwaite beds in one list. 



The Stauroceplialus Limestone of Skelgill is succeeded at the 

 Upper Bridge by the Ashgill Shales, which ai'e seen in a very 

 fossiliferous condition on a small knoll by the roadside close to the 

 Ijridge. The Stauroceplialus Limestone is not very fossiliferous in 



