Abstract
LONDON. Geological Society, Dec. 18. Frederick Walker: The geology of the Shiant Isles. The Shiant Isles form a small uninhabited archipelago in the North Minch, some five miles east of the Park district of Lewis. The group is made up almost entirely of crinanite sills separated by relatively thin argillaceous strata which have undergone considerable contact alteration, but the fossil content of which (ammonites, belemnites, and one species of Inoceramus) assigns them to a low position in the Upper Lias. The two largest islands are each over a mile in length, and are joined by a shingle beach. A third large island lies about a mile to the east, and is also to a great extent made up of a single thick sill of crinanite. East of this island, however, the crinanite passes gradually into syenite, towards the centre of the sill, the thickness of the alkaline rock being at least 60 feet. The age of the igneous activity is almost certainly Tertiary, and is probably the same as that of the Trotternish sills in Skye. Although glacial strip are not seen on the islands, their general aspect indicates a flow of ice from south to north during the Glacial Period.
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Societies and Academies. Nature 125, 33–35 (1930). https://doi.org/10.1038/125033a0
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DOI: https://doi.org/10.1038/125033a0