ON THE STOCKDALE SHALES. 703 



the spinif/erus-zone, without the intervention of any Graptolitic 

 shales. They contain many calcareous, nodular bands towards 

 the summit, forming an impure limestone some 10 feet in thickness. 

 Our attention was first called to this calcareous band by Prof. 

 Hughes, and a number of fossils occur in it. We have found : — 



Lindstroeinia, sp. 



Favosites, 



Phacops elegans, Boecl: ^ 8ars. 



Cheirurus bimucronatus, Murch. 

 Illaenus Bowmanni, Salt. 

 Leptsena quinquecostata, M^Coy. 



The band strongly resembles that of the zone of Acidaspis erina 

 ceus as seen at Torver Beck, and there is no doubt as to the identity 

 of the two deposits, though the characteristic Acidaspis has not yet 

 turned up in the Spengill section. 



Ac 5. The zone about to be described has been found in no other 

 section in the district, and indeed there is no doubt that it is absent 

 all along the line of outcrop of the Stockdale Shales in the central 

 district, as we have frequent opportunity of seeing a passage from 

 the underlying beds into the Browgill group. 



A waterfall in the Spengill section here separates the lower ravine 

 which we have described from an upper one, and this waterfall is 

 found to be determined by a mass of hard blue mudstones, which 

 also form cliifs on each side. The cliff on the right bank is seen to 

 form a projecting cornice, and immediately under this cornice 4 inches 

 of very hard black Graptolitic shale occur. Prom this band we 

 extracted a number of specimens of Rastrites maximus, Carr., and 

 one example of Monograptus jaculum, Lapw. 'No doubt other fossils 

 also occur ; but the spot is a dangeroas one, on account of the 

 broken nature of the rock forming the cornice. These beds strike 

 across the stream at the foot of the waterfall, and are again seen at 

 the foot of the cliff on the left bank ; but pieces of the shale are 

 difficult to extract here. The characteristic Rastrites maximus was 

 found here also. The blue mudstones above this band are 24 feet 

 thick, and at the summit of them and forming the top of the cliff 

 over which the water falls is another band, also 4 inches thick, very 

 similar to the former, though lighter in colour, and likewise con- 

 taining numerous examples of Rastrites maximus. We speak of 

 these black shales with the intervening mudstones as constituting 

 the Zone of Rastrites maximus. 



The upper black band of the R.-maximus zone is at once suc- 

 ceeded conformably by the lowermost Browgill Beds. 



Ba 1. The Browgill Beds occupy the upper ravine, which runs 

 obliquely to the strike, so that we meet with a generally ascending 

 succession, until we reach a second waterfall, which marks the 

 upper end of this ravine. Above the R.-maximus beds are nineteen 

 feet of ordinary pale green shale, after which we meet with four 

 feet of pale green and bluish-grey bands with some thin dark seams. 

 These are well seen on the right bank of the stream a little above 

 water-level, and a few yards above the waterfall, where they are 

 extremely conspicuous, owing to the stripes of the different-coloured 

 bands. Above them are three feet of unstriped bluish-grey beds, on 



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