294 Rev. D. Williams ofi the Geological Position of the 



where Mr. Weaver observed them dipping south, proves no- 

 thing by inference even ; for the latter very commonly dip 

 towards the S.W.; and the Floriferous Beds being almost 

 everywhere arched and inflected, as are the Trilobite Slates 

 along their southern terms, the ascending plane of undulation 

 or inflexion would place them at Muddlebridge in true paral- 

 lelism with the Trilobite Slates, supposing them to dip S.W. 

 and to have deviated half a mile out of their mean line of 

 bearing. The other instance cited of Rumson Lane S. of 

 Barnstaple, is not only high up among the Passage Beds of 

 No. 8, (and if not within the very confines of the culm-mea- 

 sures certainly in the neutral ground) but altogether so insig- 

 nificant in dimension, in such a decomposing loose condition, 

 and so concealed by herbage, tangled briar and brushwood, 

 that I should invariably reject such from my field-book, as 

 utterly inconclusive evidence for almost any purpose. Ad- 

 mitting then these instances to be ambiguous, what evidences 

 have we along the north and south borders of the trough to 

 explain them one way' or the other? I must here observe, 

 that when I use the term " Coddon Hill grits," I mean a 

 band of rock almost inorganic, but of peculiar and strongly 

 characterized mineral type, which everywhere includes the 

 little trumpery insulatic and elliptical bunches of limestone, 

 which I term the *' Possidonia," and Mr. Weaver the " Car- 

 boniferous." These grits are admitted on all hands to con- 

 stitute the base, and to be an integral part of the Floriferous 

 series or culm-measures. Now had Mr. Weaver extended 

 his walk along the coast half a mile north of his Muddlebridge 

 inference, he would have observed, first, these grits alterna- 

 ting with sundry beds of the Floriferous, No. 9, and at length, 

 by a gradual loss of their silica, passing by an insensible trans- 

 ition into the Trilobite Slates ; and a more undeniably con- 

 vincing passage of one great series into another probably can- 

 not be shown on the face of the e£.rth. Nor is this all; tracing 

 the northern confines of these grits, that is, along the line 

 where they approach nearest to the Trilobite Slates, often- 

 times having identified them with certainty, we suddenly find 

 their immediate continuation to become as true a Trilobite 

 Slate, with its characteristic fossils, as can be seen anywhere, 

 till eventually at Monbath, on the N. of Bampton, a section of 

 the turnpike road to Watchet, discloses them actually inter- 

 calated deep among the Trilobite Slates. If these and count- 

 less other gradations and alternations along the north border 

 of the trough, will not satisfy Mr. Weaver of a true con- 

 formity, I invite his attention to the results of two years' close 

 and cautious observation along the south border, viz. that 

 from the west flunk of Durtmoor to the Atlantic E. and W., 



