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Published online by Cambridge University Press: 01 May 2009
A Dyke of pre-Tertiary age is exposed in the lower course of the Usway Burn, a tributary of the Coquet. It is intruded among the Cheviot igneous rocks, and crosses the burn in a somewhat northeasterly direction. In hand-specimens the rock appears black or dark brown with a sub-vitreous lustre, and contains porphyritic crystals which are quite visible to the unaided eye. It weathers a bright red colour and even the fresh portions are streaked with red veins of agate.
page 104 note 1 “Notes on the Cheviot Andesites and Porphyrites,” by Teall, J. J. Harris, M.A., F.G.S,: Geol. Mag., 04, 1883.Google Scholar
page 106 note 1 Teall, , Geol. Mag., 1887Google Scholar, “Notes on Cheviot Andesites and Porphyrites,” p. 150: “In this case the bulk of the foreign matter must be greater than that of the felspar substance, and yet the felspar has impressed its character on the compound mass.”
page 106 note 2 Teall, , Q.J.G.S., 1884, p. 229.Google Scholar
page 108 note 1 “Notes on the Crookdene and Related Dykes,” by Heslop, M. K. M.Sc., and DrSmythe, J. A., read before the Geological Society, 11 17, 1909.Google Scholar