540 J. E. Ilarr — The Wenlock and Ludlow strata — 



tiling like 10,000 feet of Wenlock strata in the district, and only 

 two or three thousand of Lower Ludlow. I hope to show, however, 

 that the Lower Ludlow comprises all the strata between the top 

 of the Brathay Flags and the calcareous deposit referred to the 

 Aymestry limestone at the top of the Bannisdale Slates ; in other 

 words, that the three divisions of the Coldwell Beds, the whole of 

 the Coniston grits, and the whole of the Bannisdale slates excepting 

 the calcareous summit ( = Aymestry limestone) are of Lower Ludlow 

 age. My reasons are as follows: — (1) At the end of the period of 

 deposition of the deep-water Brathay Flags which are of uniform 

 lithological character from top to bottom, and of very fine material, 

 there was a marked change producing much shallower water deposits 

 which are comparable in lithological characters not with the Wenlock 

 but with the Lower Ludlow shales of other areas. It is possible 

 that the Lower and Middle Coldwell Beds do represent tbe Wenlock 

 Limestone of other areas, but I think not, and believe that the 

 Wenlock Limestone is absent, and that these Lower and Middle 

 Coldwell Beds are Ludlow. 



(2) On account of the nature of the graptolites found in the 

 Moughton whetstones, which immediatelj' succeed tlie Brathay 

 Flags of Austwick. The graptolites are Monograptiis dubins and 

 M. Nilssoni. These two species are found in the ' Cardiolaskiffer ' 

 of Scania, and Nilssoni is limited to the base of the ' Cardiolaskiffer.' ^ 

 These Cardiola Beds are correlated by TuUberg with our Lower 

 Ludlow.- Again, in Lapworth's paper on the geological distribution 

 of the Rhabdophora, M. Nilssoni, is recorded from Lower Ludlow 

 rocks only in the table showing the distribution of the various 

 species of graptolite. and he speaks of the zone of M. Nilssoni as 

 lying between the Wenlock and Aymestry limestones, and forming 

 the Lower Ludlow shales of IMurchison. 



(3) The fossils of the Middle Coldwell Beds give little or no 

 indication of age, and might equally well be Wenlock or Ludlow ; 

 but this is not the case with the Upper Coldwell Beds. These beds 

 have the fauna of the Cardiolaskiffer of Sweden (which, as already 

 stated, is correlated by Tullberg with the Lower Ludlow). But the 

 fossils of the Upper Coldwell Beds themselves strongly support 

 their Ludlow affinities. I have indicated in the list those which are 

 confined to the Ludlow, those which occur in the Wenlock also, and 

 that (I can find but one, and the identification of that is doubtful) 

 which has been elsewhere found in the Wenlock only. I would not 

 lay much stress on this, except as showing that the probabilities are 

 quite as much in favour of the beds being Ludlow as of their being 

 Wenlock ; but when we deal with the graptolites we have more 

 certain evidence, for though the three species found in the Upper 

 Coldwell Beds have been recorded from the higher Wenlock strata, 

 they only are found in the abundance in which they lie in some of 

 the Upper Coldwell Beds, in Lower Ludlow strata at home and 

 abroad. Furthermore, some of the fossils limited to the Lake 

 District pass up into the Coniston Grits and even into the Bannisdale 



' Cf. TuUberg, Skanes graptoliter. Part I. p. 14. 



2 Cf. Aft. ur. geol. f oren. i. Stockholm Fordhandl. 1880, No. 59, Bd. V. No. 3. 



