Published online by Cambridge University Press: 01 May 2009
The basalt of Mullion Island, with the intercalated radiolarian chert, is well known from the descriptions of Teall and Howard Fox.1 It is a fine-grained minutely vesicular basalt, consisting mainly of radiating felspar laths and interstitial pale purplish-brown augite, and occurring in peculiar pillowy or bale-like masses. Owing to this curious structure and its intercalation with the chert the basalt is considered to be a submarine lava.
1 Quart, Journ. Geol. Soc, vol. xlix (1893), p. 211.Google Scholar
2 Trans. Roy. Geol. Soc. Cornwall, xii (1), 1896, p. 39.