The Granites of the Scilly Isles and their Relation to the Dartmoor Granites

Assuming that all the West of England granites are due to the same cause, namely, late adjustments of the Post-Carboniferous ‘Revolution’, it would follow that the successive movements in one part of the region should be represented in the remainder. The object of this paper is to show that, when the two flanking masses (the Dartmoor and Scilly Isles granites) are compared, the two areas show a similar isostatic or elastatic correction sequence of intrusions. Slight differences in composition, due to differences in the original rock-material from which these granites are derived, are to be expected. The order of separate successive intrusions found in the eastern-most laccolite of Dartmoor by Dr. A. Brammall, and by myself in the north-eastern quarter of the same granite-mass, can be observed in the Scilly Isles laccolite, and may be tabulated as follows:—