Dr. J. E. Marr — The Dufton mid Keisley Groups. 485 



crystalline limestone to the south of it at the west end of the quarry. 

 To the north of this belt is the fine exposure of the northern face. 

 The beds are dipping almost due south at an angle of 45°. They consist 

 essentially of nodular grey limestone, which, however, is in places 

 stained pink with hsematite. Similar staining occurs in the limestone 

 of many other parts of the hill. Where unstained, the limestone, as 

 before stated, closely, resembles the nodular limestone of Swindale 

 Beck and Billy's Beck. Dipping with the limestone is an olive- 

 green shale, which, however, is affected by many contortions, which 

 cause it to undulate on the face of the quarry. It contains a number 

 of nodes of limestone which will be further considered at a later 

 stage, and is crushed to so great an extent as to break into papery 

 sheets with very glossy surfaces. No fossils were seen in this, but 

 a similar rock in a less crushed condition, occurring west of the wall 

 which bounds the west end of the quarry, yielded some indeterminable 

 fossils to Mr. Fearnsides' hammer. The rock there closely resembles 

 the Swindale Beck rock to which Professor Nicholson and I originally 

 restricted the term " Staurocephalns Limestone," and as the two occur 

 in the Keisley Limestone they further increase the resemblance of 

 the Swindale section to those of the Keisley Quarries. 



Two or three years have elapsed since I detected graptolites of 

 Skelgill Shale age in the road cutting east of the Old Limekiln and 

 south-east of the west quarry (at S.). At Easter Mr. Fearnsides 

 obtained a number of graptolites from this locality, and was able to 

 prove that the zone was that of Dimoiphograptus confertus. The beds 

 are dipping a little west of south. As there is not enough room for 

 the Ashgill Shales between this exposure and the nearest outcrop of 

 Keisley Limestone, there is undoubtedly a fault separating the 

 Skelgill Beds and the Keisley Limestone. 



So far as the relations of the Keisley Limestone to other strata are 

 concerned, our observations show : (i) that the highest beds of the 

 Dufton Series are marked by calcareous black limestone with 

 subordinate shales, the limestones containing few fossils save crinoids ; 

 further, that these calcareous beds occur in the Keisley section and 

 in that of Swindale ; (ii) that the change from the dark Dufton Beds 

 to the lighter-coloured Keisley strata is abrupt, but there does not 

 appear to be any unconformity ; (iii) that the Keisley Beds consist 

 mainly of fairly pure limestone, but that more argillaceous beds are 

 interstratified with the purer limestone ; from these more argillaceous 

 beds Professor Nicholson and I extracted the fauna of our 

 Staurocephalns Limestone ; (iv) that the Keisley Beds of Swindale 

 appear to be succeeded conformably by the Ashgill Shales. 



I now turn to a consideration of the peculiar development of the 

 Keisley Limestone in the Keisley exposures. I have elsewhere 

 argued that it is a ' knoll ' of limestone which has been thickened by 

 folding and taken on peculiar structure during that folding, and 

 recent examination tends to confirm this view. 



The section figured shows that folding on a considerable scale has 

 affected the rocks of the east quarry, and abundant minor folds are 

 proved to exist in the west quarry by the puckering of the shales. 



