. Bulletin of the British Museum (Natural History), Geology. 48 D. A. T. HARPER. Fig. 2 Correlation of Ordovician-Silurian junction sections across the Girvan district with each other and the established shelly stages and graptolite biozones. are developed at various levels in the formation. The lower 2 m of the formation exposed in the High Mains trench (Harper 1981: 250) comprises grey-green fine-medium grained, thinly bedded sandstones, whilst the upper 5-5 m is a hard medium-grained, thickly-bedded sandstone. Changes in grain size, bedding characteristics and faunal composition indicate a
. Bulletin of the British Museum (Natural History), Geology. 48 D. A. T. HARPER. Fig. 2 Correlation of Ordovician-Silurian junction sections across the Girvan district with each other and the established shelly stages and graptolite biozones. are developed at various levels in the formation. The lower 2 m of the formation exposed in the High Mains trench (Harper 1981: 250) comprises grey-green fine-medium grained, thinly bedded sandstones, whilst the upper 5-5 m is a hard medium-grained, thickly-bedded sandstone. Changes in grain size, bedding characteristics and faunal composition indicate a minor regres- sion within the sequence. In view of the incomplete exposure and an apparent absence of Figs 3-22 Brachiopods and trilobites from the High Mains Formation (Hirnantian), High Mains trench, Girvan. Repository: Hunterian Museum, Glasgow. Fig. 3, fossiliferous block of the High Mains sandstone dominated by internal moulds of both pedicle and brachial valves of Hindella crassa (J. de C. Sowerby) incipiens (Williams) and crinoid ossicles, x 1. Figs 4, 8, Plaesiomys aff. porcata (M'Coy). 4, HM L12238, latex cast of internal mould of brachial valve, x 2; 8, HM LI2239, latex cast of external mould of pedicle valve, x 2. Figs 5, 9, 13, Eochonetes cf. advena Reed. 5, HM L12115, internal mould of pedicle valve, x 4; 9, HM L12117, latex cast of internal mould of brachial valve, x 4; 13, HM L12118, latex cast of external mould of pedicle valve, x 3. Figs 6, 7, 10, 11, Hindella crassa (J. de C. Sowerby) incipiens (Williams). 6, 10, HM L12242, latex cast and internal mould of pedicle valve, both x 2; 7, HM LI2244a, external mould of brachial valve, x 3; 11, HM L12244b, latex cast of internal mould of brachial valve, x 3. Figs 12, 14-16, Eostropheodonta aff. hirnantensis (M'Coy). 12, HM L12105, latex cast of internal mould of brachial valve, x 2; 14, HM L12104, internal mould of pedicle valve, x 1; 15, HM L12103, latex cast of external mould of pedicle valve, x 2; 16, HM L12653, l
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