Abstract
LONDON. Geological Society, June 11.—Dr. Aubrey Strahan, president, and afterwards Mr. W. Whitaker, in the chair.—Dr. Hans Salfeld: Certain Upper Jurassic strata of England. The localities dealt with are the Dorset coast from Kimmeridge to Abbotsbury, and the Wiltshire exposures at Swindon and Westbury. The formations concerned are the Portlandian, Kimmeridgian, and for a starting-point the Upper Oxfordian. The Upper Oxfordian = upper part of the English Corallian (+Kimmeridge Clay locally) is divided into three zones, found at Osmington, Westbury, and Swindon. The Kimmeridgian is divided into five zones, and is equal mainly to the Lower Kimmeridge Clay of English authors. The Portlandian is divided into nine zones; but the term as used includes the Portland Oolites, Portland Sands, and Upper Kimmeridge Clay of British authors. Three new genera of ammonites are named, and two new zonal species of ammonites defined.—A. Jowett: The volcanic rocks of the Forfarshire coast and their associated sediments. In Forfarshire these sediments are frequently amygdaloidal, the production of the cavities having been accompanied by the buckling and fracturing of the layers of sediment. Such effects may result from the pouring of molten rock over wet unconsolidated sediment; steam being produced within the sediment, but unable to escape owing to the presence of the overlying rock. Further evidence of the pouring of molten rock into water is furnished by the occurrence of a rude pillow-structure in some of the lavas. Several lenticular conglomerates are inter-bedded with the volcanic rocks, resting upon eroded surfaces of the latter. Most of the volcanic rocks are olivine-basalts, rhombic pyroxene as well as olivine sometimes being present. Some contain rhombic pyroxene to the exclusion of olivine. The fine sediments consist of a variable proportion of quartz and mica and a little felspar, together with chlorite, iron oxides, and occasional minute fragments of volcanic rock. Calcite, quartz, chalcedony, and chlorite are the commonest minerals in the amygdales, in both lavas and sediments.—J. Parkinson: A group of metamorphosed sediments situated between Machakos and Lake Magadi in British East Africa.
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Societies and Academies . Nature 91, 440–443 (1913). https://doi.org/10.1038/091440a0
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DOI: https://doi.org/10.1038/091440a0