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II.—On Some Recent Classifications of Welsh Pre-Cambrian Rocks

Published online by Cambridge University Press:  01 May 2009

T. G. Bonney
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Extract

Two papers, presented by Prof. Hughes to the Geological Society during the last twelve months, call for some comment from myself, as in many respects they controvert, directly or indirectly, opinions which I have expressed before the same Society. In the debates which followed I objected to the imperfect evidence on which these criticisms were founded; and as the author repudiated with some warmth my right to demand that conclusions founded not only on field work, but also on microscopic study, should not be assailed from the former point of view alone, I will venture to state the reasons why I so did, and intend so to do on any future occasion that may arise.

Type
Original Articles
Information
Geological Magazine , Volume 7 , Issue 7 , July 1880 , pp. 298 - 303
Copyright
Copyright © Cambridge University Press 1880

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References

page 298 note 1 Read May 14, 1879, and Feb. 25, 1880.

page 298 note 2 Quart. Journ. Geol. Soc. vol. xxxv. pp. 309, 321.Google Scholar

page 299 note 1 Quart. Journ. Geol. Soc. vol. xxxiv. p. 682.Google Scholar

page 300 note 1 I was formerly inclined, from the evidence of strike and in defect of proof of faults, to place the Careg Goch grits on a lower position than those of Twt Hill, but subsequent examination has shown me that I was misled (partly by defects on the map) on the former occasion, and that there is good reason to infer the presence of faults, which cause the general trend of the beds to correspond more nearly with the line of the ridges.

page 301 note 1 Discovered by Mr. Tawney.

page 301 note 1 Certain reasons connected with the proximity of the cottages make it difficult, especially in summer time, to examine the ground inch by inch.

page 302 note 1 On map, about half-way between l in Trawscanol and T in Tairffynnon.

page 302 note 2 Part of that which Prof. Hughes admits he has not worked out, Quart. Journ. Geol. Soc. vol. xxxiv. p. 687Google Scholar; the key of the position as it seems to me.

page 303 note 1 Published while this paper is passing through the press in vol. xxxvi. of the Quarterly Journal (p. 237). The author, however, has almost suppressed the portion of the paper in which this theory was enunciated (see p. 183 of this Magazine).

page 303 note 2 Knowing that Mr. S. Allport had also examined some of these rocks, I wrote to ask his opinion. He indorses my view, especially as to the Holyhead schists, which he has recently studied, in the strongest terms.