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Published online by Cambridge University Press: 01 May 2009
There is no essential difference between Nos. 1, 2, and 3, and No. 4: only differs in being harder, not liable to disintegration by water, and in containing more arenaceous and less argillaceous matter than the other samples. Calcareous matter in all the samples is from 15 to 20 per cent., and consists almost entirely of shells of Foraminifera. There is a considerable amount of sulphur, chiefly as pyrites, greatest perhaps in No. 3, and fragments of Manjak occur in No. 1.
page 276 note 1 Ussher: “The Culm Measure Types of Great Britain”; London, 1901.
page 276 note 2 Manjak is a substance originally found in Barbados. It is geologically coal, but chemically a form of bitumen. It is described in Schomburgk's “History of Barbados,” pp. 551, 569; and (as coal) in Proc. Sci. Assoc. Trinidad, 1877, p. 110 (see Guppy on Coal, etc., Proc. Viet. Inst. Trinidad, p. 507).