Abstract
LONDON. Geological Society, June 22.-Mr. R. D. Oldham, president, in the chair.-Dr. C. T. Trechmann and L. F. Spath: The Jurassic of New Zealand. The Jurassic beds of New Zealand comprise an important set of sediments, probably 10,000 ft. in thickness, exposed at certain points extending over the length of the North and South Islands. They follow the Trias with apparently perfect conformity. The affinities of the fossils from the Lower Lias to the Upper Jurassic formations are with those occurring in the Jurassic of the Argentine Andes, Western Australia, the Sula Islands, the Spiti Shales of the Himalayas, and the Jurassic deposits of Kutch. Descriptions of New Zealand ammonites from the British Museum collections, notably a small fauna of typically Mediterranean aspect, -which is referred to the Middle Lias, were given.-F. Dixey; The norite of Sierra Leone. The norite of Sierra Leone constitutes a complex of which the oldest and most important member is an olivine-norite. The complex forms the mountainous mass which, with a narrow coastal plane of Pleistocene sediments, makes up the Sierra Leone peninsula. The norite was intruded in the form of a huge stock; it has no marginal or basic modifications, while its junction with older rocks is obscured by the Pleistocene sediments. The complex is probably somewhat later than Pre-Cambrian in age. The main intrusion of norite was invaded in succession by minor intrusions of younger norites, norite-pegmatite, beer-bachite, norite-aplite, and dolerite. Features of the older norite are welWeveloped flow-banding, a series of binary and ternary intergrowths of the common minerals, and metamorphism due to the minor intrusions. Iron-ores occur in the norite as small masses, narrow schlieren, and disseminated grains; they are highly titaniferous. Sulphides and other economic minerals are rare or absent.
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Societies and Academies. Nature 107, 638–640 (1921). https://doi.org/10.1038/107638b0
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DOI: https://doi.org/10.1038/107638b0