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Societies and Academies

    Naturevolume 115pages694695 (1925) | Download Citation

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    LONDON. Geological Society, March 25.—C. B. Brown and R. A. Baldry: On the clay pebble-bed of Ancon (Ecuador). This bed, varying in thickness from 550 to 900 feet, crops out on the southern shore of the Santa Elena Peninsula, Ecuador. It consists of polished, rounded, or sub-rounded pebbles of harder clay, embedded in a matrix of softer clay, and contains large and partly rounded boulders of sandstone, foraminiferal limestone, grit, polished quartz-pebbles, etc., and masses of limestone. It is considered to be the result of a great post-Oligocene over-thrust in soft sands and clays of Tertiary age. The direction of thrusting is from the east-south-east (the Brazilian over the Pacific block).—J. I. Platt: The pre-Cambrian volcanic rocks of the Malvern inlier. The region described occurs about the central part of the Malvern Range, and consists largely of volcanic rocks, which are of pre-Cambrian age, and belong to a distinctly sodic suite comprising soda-rhyolites, keratophyres, and spilites. There are a few pyroclastic rocks developed. Although those examined were of an acid composition, there can be little doubt that more basic types also occur. A number of minor intrusions have been injected into the lavas. In the south-west of the area described, two dykes of a comparatively fresh ophitic dolerite crop out, while a subophitic variety of the same type is found in the north-west. There are several dykes and a volcanic neck of epidiorite in the east of the area.

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    https://doi.org/10.1038/115694a0

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