The Green Ammonite Beds of the Dorset Lias

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Abstract
I. Introduction. The Green Ammonite Beds comprise those horizons of the Dorsetshire Lias which lie above the Belemnite Stone—horizon of Beaniceras —and below the Three Tiers—nearly the lowest limit of Amaltheus . They bear this connotation in the memoirs of the Geological Survey, and include a greater thickness than was intended by Day (1863, p. 291), who first coined the term for 18 feet of clays lying in the lower part of the series as here defined, and yielding nodules in which the typical green ammonites are to be found. The chambers of these ammonites are often filled with greenish calcite—hence the vernacular name. The Green Ammonite Beds form part of the Upper Lias Marls of De la Beche's earlier account (1826), and the middle part of the “marls and slaty marls with several beds of indurated marl and earthy limestone in the lower part, micaceous in the higher—350 ft.” of his later account (1839, p. 223). They are the equivalent of Oppel's “Davöi-bett”, or “zone des Amm. Davöi ” (Oppel, 1856–8, pp. 117, 126–9, 148, 151) and he records their occurrence on the Dorset coast (p. 129) as follows: “An der Küste von Charmouth bei Lyme Regis (Dorsetshire) fand ich dagegen nicht allein ein grosses und deutliches Exemplar von Amm. Davöi [also recorded on p. 161], sondern in seiner Begleitung auch die in Schwaben mit ihm zusammenliegenden characteristischen Arten: Amm. capricornus, Henleyi [also recorded on p. 164], Belemnites umbilicatus [also recorded on p. 154], elongatus [also recorded on p. 152], clavatus [also

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