File:The Quarterly journal of the Geological Society of London (1907) (14777447145).jpg

Identifier: quarterlyjournal63190geol (find matches)
Title: The Quarterly journal of the Geological Society of London
Year: 1845 (1840s)
Authors: Geological Society of London
Subjects: Geology
Publisher: London (etc.)
Contributing Library: Smithsonian Institution Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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a garnet-tourmaline-orthogneiss is asso-ciated with a fine-grained mica-schist, so closely as to produce abanded composite gneiss by a process, apparently, of lit-par-litinjection. Examination of numerous gravels shows that thefoliated rocks contain monazite. (4) The unfoliated group, developed principally on the westernside of the Oban Hills, but sporadically over the entire district,consists of many varieties of granite, of tourmaliniferous pegmatites,and of aplite-dykes. (5) The youngest rocks are a series of olivine-basalt dykes,which, from a comparison with dykes and sills cutting Cretaceousrocks on the Cross and Aweyong Rivers, are considered to be of post-Cretaceous age. (6) A group of phyllites and subordinate grits altered by acidicintrusions, now gneissose, into various forms of Eruchtschiefer(spotted slates), micaceous and staurolite-schists, and of garnet-and andalusite-hornfels, occur near Uwet on the Calabar River. Fig. 1. SKETCH-MAPof the OBAN HILLS Scale of Miles .prf
Text Appearing After Image:
□ Gncissose i£Granitic Scries. I Cretaceous,f 1 • • Tertiary & recent Series. E. 9 Long. Yol. 6^.~) THE GEOLOGY OF THE OBAN HILLS. 315 Taking this series (6) as a whole, proofs of contact-metamorphismare abundant. At almost the lowest point of the Uwet Kapids isan example of an exceptionally-fine Fruchtschiefer (spotted slate),in which the prisms discernible on a weathered surface measureoccasionally 4 inches in length. The rock in which these growths oecur is a somewhat alteredslate, in which white mica has been abundantly developed. Someof these metamorphic effects have doubtless been caused by theintrusion of granites, for these rocks form both banks of the riverabove Uwet Bungalow, almost as far as the lowest rapids, and aremet with again about 4 miles up stream. Some 2; miles up stream,that is to the northward, occurs a staurolite-schist, and exceedinglywell-formed crystals of the characteristic mineral are found in thepans taken from the gravels of streams between Ewe

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