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I.—Four Theories of the Age and Origin of the Dartmoor Granites

Published online by Cambridge University Press:  01 May 2009

A. K. Hunt
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Extract

Four Theories of the Age and Origin of the Dartmoor Granites have been lately current, viz.:—

(1) The ordinary Plutonic of Sir H. de la Beche.

(2) The Laccolitic-Plutonic of Mr. W. A. B. Ussher.

(3) The Volcanic of Mr. K. N. Worth.

The above all assume the exclusively post-Carboniferous age of the granite, owing to its intrusion into the adjacent Carboniferous rocks;one of the best attested facts in geology.

(4) The combined pre-Devonian non-intrusive and post-Carboniferous intrusive (both plutonic), advanced by myselfin1889.

Mr. Ussher has recently withdrawn his provisional laccolitic hypothesis, on stratigraphical grounds,infavour of one which is practically equivalent to No. 4.

As it is impossible to compress the work of some four years into a magazine article, the present paper must be confined to a sketch of my main argument.

My friend Mr. Worth has, with characteristic generosity, lent me the diagrammatic woodcut illustrating bis ideal volcano;accompanied by the following remark:“Please do not limit your views of me;you owe it to yourself to make your case as strong as possible, and we shall not differ outside our theories.”A too generous opponent indeed, and one hard to oppose.

Type
Original Articles
Information
Geological Magazine , Volume 1 , Issue 3 , March 1894 , pp. 97 - 108
Copyright
Copyright © Cambridge University Press 1894

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References

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