458 n. B. Woodivard — Inversion of Carhoniferous Strata. 



The influence that these anticlinal disturbances may have in com- 

 plicating the probable Coal-field on the south of the Mendips is a 

 point that should not be neglected. 



Without wishing to ride my own theory too hard, I cannot help 

 thinking that the subject must be looked at in this large way, and 

 although I may have to modify the direction or upthrow of the 

 faults whose help I have invoked in my necessarily diagrammatic 

 sections, yet the explanation itself seems to accord better with the 

 ascertained disturbances of the area than one which conjectures that 

 they have in some way been folded over from the Downhead anti- 

 clinal of the Mendip range. The physical structure is entirely 

 opposed to this folding over, as I showed in my former paper.^ 



That the structure might have assumed such a form as that repre- 

 sented by your Indian correspondent^ is by no means impossible, 

 but we lack the positive evidence. The masses of Limestone would 

 then be the result of fragments dislodged from the denuded escarp- 

 ment, as Mr. Brice has conjectured ; yet when we come to draw out 

 this supposed structure on a true scale, more difficulties arise, so it 

 seems to me, than on the theory I have proposed, even if we take 

 into consideration the evidence of partial inversion of the Millstone 

 Grit, and perhaps also of the Old Eed Sandstone at East End. 



The existence of such Limestone masses in the midst of an area 

 of Coal-measures is not without its parallel elsewhere in England. 

 There are patches of Limestone situated in the Coal- tract of Clapton - 

 in-Gordano, but I have never visited this area ; and although they 

 have been traced out on the map of the Geological Survey, their 

 occurrence has not, so far as I am aware, been explained. In 

 Devonshire, too, in the midst of the Culm-measures, there are some 

 very puzzling masses of Devonian Limestone, which have been alluded 

 to as indicating unconformability ; but here there are numerous faults, 

 and the difficulty lies in tracing across country those faults actually 

 determined in the Culm-measures, owing to the absence of any 

 marked beds in this series. 



Were a geologist, indeed, whose mind was filled with Glacial 

 theories, to come directly from Norfolk or Lincolnshire, having been 

 impressed with the really wonderful transported mass of Chalk met 

 with in the one county, or of Inferior Oolite and Marlstone that are 

 occasionally met with in the other, he might be led to suggest a 

 similar explanation to account for the isolated masses of Limestone 

 that occur on the Coal-measures of Somersetshire. But, after all, 

 the question is not which agent is most capable of producing the 

 phenomena, but which agent capable of the work is most in accord- 

 ance with facts ; and I still think a word may be said in favour of 

 the faulted- anticlinal theory. At the same time I fear the verdict 

 must yet remain one of not proven. 



^ jSTo traces of Millstone Grit in situ have been traced either at Luckington or 

 Vobster, but Mr, McMurtrie has noticed blocks of it in a field to the north of Upper 

 Vobster. In my diagram-section I have introduced the Millstone Grit here. The 

 occurrence of stray blocks, however, is but uncertain evidence ; similar blocks occur 

 on the sui'face of the ground near East Harp tree. 



2 See Geul. Mag. Dec. II. Vol. II. p. 567. 



