A. Champernowne — Age of the Ashhurton Limestone. 411 



it goes, is cei'tainly direct evidence, but we shall see that there 

 is abundant indirect evidence, tending to show that they are one 

 and the same. 



Mr. Godwin-Austen did not, as far as- I am aware, ever hint at 

 these limestones .having a uniclinal structure, but I am not familiar 

 with his earlier papers, though quite so with that in the Trans. Geol. 

 Soc. 2nd series, vol. vi. In the latter the Ashburton limestone is 

 distinctly referred to as a " lower limestone." ^ 



As regards the lithological varieties to be met with in this range 

 of limestones, we need not dwell at any length. Suffice it to say 

 that it is usually well-bedded and dark-coloured ; occasionally 

 dolomitized but not extensively so, like the Dainton mass and 

 others which are crystalline and run into light colours ; but that in 

 other respects it may be paralleled with almost any of the limestones 

 of South-East Devon or Plymouth. Moreover, it is quite possible 

 that the highest beds, which at Dartington and elsewhere are the 

 dolomitized portions, may be seldom seen, that is, of course, provided 

 the iini-synclinal folding can be proved. But be this as it nia}^ 

 dolomitization is always very impersistent, and the causes of its 

 phenomena still very enigmatical. 



We now come to the fossils ; the collector will be sadly dis- 

 appointed in these limestones. I know of no spot where fossils can 

 be extracted from the matrix, but the records can be fairly well read 

 in the polished slabs of Ashburton marble, on the large sawn blocks 

 in the quarry. Large Stromatoporce of the same kind as those which 

 characterize the Ogwell, Dartington, etc., limestones, are very abun- 

 dant, two may be cited — one of loosely reticulated and open structure 

 (query, not named or var. of S. polymorplia, Goldf.) — another of 

 remarkably fine structure, which, with my kind friend Dr. Carter, I 

 regard as belonging to the same section, or identical with S. typica, 

 Eosen, the concentric layers "'having the form of rhombs, triangles 

 and pentagons,"^ thus simulating, though lacking the geometrical 

 constancy of the Hexactinellidce. 



Interspersed with these we frequently observe fragmentary sections 

 of String ocephalus, shells which, whether from the large septum 

 projecting from the concave side, or from the punctate shell- 

 structure, are not readily mistaken. Other Brachiopod sections, 

 with striae, betoken Uncites. Some portions of beds are full of 

 Gasteropoda, among which the outlines of MurcMsonia can be de- 

 tected. Others again are made up wholly of the so-called Caimopora 

 ramosa, Phillips, which is also common in the Lemon Valley S.W. 

 of Bickington, as well as in the Ogwell and Bishopsteignton beds. 

 It abounds also in the Westphalian limestone, and at Paffrath. Am- 

 plexus tortuosus, Phillips, simple Cyathophjlla, apparently few as to 

 species, Cystiphylliwt vesiculosum, Goldf., Favosites (sp.), Aulopora 

 repens, Goldf., can all be observed, and probably other forms might 

 be added to this small but significant list, which links the Ashburton 

 limestone with that of Schwelm, Elberfeld, etc. 



1 See also De la Beche, Geol. Report, p. 69. 



2 Eosen, " Ueber die Natur der Stroma top oren," p. 17 aud woodcut. 



