Dr. Wlieelton Kind — The Toredale Series. 205 



has been noticed. In that rock, however, felspar is present, 

 described as plagioclase and idiomorphic. In the boulder, the 

 dusty-looking or opaque white substance clearly is interstitial, 

 and is now steatite, a decomposition product of a rhombic pyroxene. 

 The specimen appears to be nearest to the group of the picrites, to 

 the form of that rock not containing felspar. It is somewhat 

 intermediate between the typical augite-picrite and the variety 

 distinguished by Professor Bonney as hornblende-picrite, and it has 

 a likeness to the Penarfynydd rock.^ So far as I am aware, it 

 has not been recognized in situ in the Zmutt district, and it will be 

 interesting if any climber in that neighbourhood should track it to 

 its home. The boulder being large, it most probably came directly 

 from some of the neighbouring heights, possibly from the western 

 side of the Matterhorn, gabbro, according to the Swiss map, 

 occurring from the watershed down at intervals to the neighbourhood 

 of the Zmutt glacier. This hornblende-picrite is interesting as 

 another variety of the basic igneous rocks, varying from sei'pentine 

 to gabbros, which form a widespread group, extending at least 

 from the Saas Valley to the Val d'Herens. 



IV. — On the Subdivisions of the Carboniferous Series in Great 

 Britain, and the True Position of the Beds Mapped as 



THE YOREDALE SeRIES. 



By Wheelton Hind, M.D., B.S.Lond., F.E.C.S., F.G.S. 

 [Concluded from the April Number, p. 169.) 



THE earlier part of this paper is devoted to a short epitome of the 

 stratigraphical evidence that the Yoredale rocks of Wensley- 

 dale are only the equivalents of the upper part of the Carboniferous 

 Limestone, and that the so-called Yoredale Beds of South Yorkshire, 

 Lancashire, and Derbyshire are an entirely diiferent series, which 

 occupy a position above the Carboniferous Limestone. After all, 

 the important point is the paleeontological evidence, which, to my 

 mind, is absolutely conclusive. 



On comparing the Molluscan fauna of the limestones and shales 

 of the Yoredale Eocks of Professor Phillips with that of the 

 Carboniferous Limestone of Derbyshire, it is at once seen that they 

 are practically identical. In the list of fossils given in the Appendix 

 to the Geological Survey Memoir on the country round Mallerstang,^ 

 110 named species of corals, echinoderms, annelids, crustaceans, 

 polyzoa, and mollusca are enumerated, the great majoi'ity of which 

 are common to the Yoredale Series and Great Scar Limestone. But 

 no species occur which are peculiar to the upper beds, and which do 

 not occur in the massif of Carboniferous Limestone in one locality 

 or another. On paleeontological grounds, therefore, no distinction 

 can be drawn between the Yoredale Series of Wensleydale and the 

 main mass of Carboniferous Limestone, though it would not have 

 been surprising, considering the differences of lithological character 



1 Cf. T. G. Bonney in Geol. Mag. 1880, p. 208. A. Harker, loc. cit. 

 ^ Explanation of Sheet 40, Geological Survey. 



