212 Br. Wheelton Hind — The Yoredak Series'. 



■several beds of limestone occur at various horizons in the Coal- 

 measures. But these beds have, as far as is at present known — 

 and I have examined several, and many have been reported upon 

 by officers of the Geological Survey and others — a totally distinct 

 fauna to that which is entombed in the lower limestones : the one 

 difficulty in the Midland area being whether to place the Pendleside 

 limestones in the lower or the upper division. My own view is, that 

 the fossils agree more with the fauna typical of the Carboniferous 

 Limestone than with those above. 



Again, it may be asked, why, with three distinct faunas, make 

 a twofold division ? and the answer is that, although it would be 

 impossible to draw any line of demarcation between the beds 

 containing faunas No. 2 and 1, which are so much intercalated, 

 the fauna of the lower series is so characteristically different ; or, 

 with greater reason, it may be asked why even a twofold division ? 

 The reasons for this are, first, that a review of the Carboniferous 

 rocks of the world seems to demand such ; and, moreover, the 

 fauna of the limestones, although it did occasionally reappear for 

 a brief period in the upper beds, is so typical of the lower beds ; 

 and I claim that the binary division of Carboniferous rocks is 

 therefore based solely on paleeontological grounds. Mr. E. Kidston 

 considers that the plants distributed through the Carboniferous rocks 

 " clearly indicate a great twofold division," and in the main his 

 division is identical with mine, although he does not appear to 

 recognize that the Yoredale Series of Wen si ey dale is only the 

 equivalent of the upper part of the Carboniferous Limestone ; but 

 as he says that he has seen no plants from that series, and had no 

 personal knowledge of that district, he has not based any evidence 

 for his classification on those beds. 



Geological science knows no hard and fast lines, and classification, 

 though founded on natural laws, is not a law of nature, but purely 

 utilitarian in purpose ; but to be of any service at all, even the 

 classification and division of series of strata must be based on the 

 soundest palseontological evidence. 



The recognition of the true place of the series of rocks in 

 Wensleydale, although, of necessity, abolishing the term Yoredale 

 Series as one of the primary divisions of Carboniferous rocks, does 

 not render it obligatory for that term to altogether sink into disuse. 

 The name may very well be used to denote the change of character 

 in the series, due to causes which acted locally, and to represent 

 the Carboniferous Series as it occurs in Wensleydale, Swaledale, 

 Teesdale, and the upper jDarts of Wharfedale and Eibbledale. But 

 the use of the term must be restricted to this district, and beds 

 of an altogether higher series, with a totally different fauna, must 

 be no longer confounded with them because they appear to occupy 

 a position between two arbitrary and discontinuous base-lines. 

 Currents, reefs, and the differences in depth of a shelving shore, 

 will account for any of the difficulties of tracing any one bed 

 for a distance ; and it must be remembered that much of the deposits 

 must have been extremely local, and that many strictly synchronous 



