ON THE STOCKDALE SHALES. 659 



in the course of the stream near Ambleside, which is termed Holbeck 

 Gill on the maps of the Ordnance Survey, but which has been so 

 often alluded to in geological writings under the name of Skelgill 

 (derived from the farm of High Skelgill, situated near its banks), 

 that it would be highly inconvenient to adopt any other name. It 

 is on account of the strong development of the beds of this stage, 

 in this locality, that one of us, in conjunction with Professor 

 Lapworth, has proposed for the beds the title of " Skelgill Beds," a 

 term which we propose to employ here instead of the more ancient 

 term " Graptolitic Mudstones," because there are other Graptolitic 

 beds in the district, and the term " Mudstone " is hardly so appli- 

 cable to the true Shales in which the Graptolites are found, as to 

 the bluish-grey clayey beds, devoid of stratification, which occur 

 between the different bands of Graptolitic Shale, and which do not 

 contain Graptolites. 



The upper stage of the series is well seen in the course of Stock- 

 dale Beck, which also contains a fair development of the lower 

 stage, so that the name of this beck is particularly applicable to the 

 whole series. In a tributary of Stockdale, which is called Browgill 

 on the maps of the Ordnance Survey, there is an excellent develop- 

 ment of fossiliferous beds of the upper stage, and those beds of this 

 stage which are not seen here are seen in the larger beck close by ; 

 so we propose to adopt the section at Browgill, supplemented by 

 that in the adjoining Stockdale stream, as our type section, and, for 

 the sake of uniformity, as well as in order to have the type sections 

 along the main line of outcrop of the Stockdale Shales, to substitute 

 the term " Browgill Beds " for " Knock Beds " in describing this 

 upper stage of the series. We do this with the consent of Professor 

 Lapworth, who, with one of us, originally proposed the term " Knock 

 Beds " for this series. Our classification, then, is as follows : — 



Stockdale-Shale series. ^^"^"^ i ^^7??" f ^S«- 

 Lower [ Skelgill stage. 



A. The SJcelgill Beds of Slcelgill. 



The stream of Skelgill Beck well deserves to be considered as fur- 

 nishing the type section of the lower stage of the Stockdale Shales, not 

 only on account of the magnificent section exposed along its banks, 

 but also on account of its accessibility, and the unrivalled views 

 of the Lake-district hills as seen from its neighbourhood. The stream 

 rises in the moorland immediately to the east of Wansfell Pike, and 

 enters Windermere a few yards south of the Low Wood Hotel, after 

 a course of about two miles. For the first half-mile it runs in a 

 shallow valley through volcanic rocks and the beds of the Coniston- 

 Limestone series, and then reaches a bridge over which passes a 

 cart-track from Troutbeck village, known as Hundreds Road. This 

 bridge we may speak of as the Upper Bridge. At this point the 

 stream, which has been flowing due south, assumes a south-westerly 

 direction, and enters a ravine which is in a straight line with a 



