Abstract
LONDON.
Geological Society, April 19.-Mr. H. B. Woodward, F.R.S., vice-president, in the chair.-The Blea Wyke beds and the Dogger in north-east Yorkshire: R. H. Rastall. The author describes the type-section at Blea Wyke in detail, dividing the rocks into the following divisions, enumerated in descending order:-(5) Dogger; (4) yellow beds; (3) Serpula beds; (2) Lingula beds; (1) Striatulus shales. Descriptions and fossil lists from these divisions are given, and the succession is compared with others.- Notes on the geological aspect of some of the north-eastern territories of the Congo Free State: G. F. J. Preumont, with petrological notes by J. A. Howe. This paper is a brief sketch of the geological structure of the northern part of the Congo State, from Buta on the River Rubi and Bima on the Uelle in the west, to Lado and Dufile on the Nile. In the whole of this region, the only post-Primary rocks met with, other than those of comparatively modern alluvial origin, were chocolate-coloured shales (Buta Shales) and sandstone, and an Oolitic limestone, on the extreme west. From the Lipodongu Falls on the Rubi, and thence through Poko to Rungu, on the Bomokandi River, none but granitic rocks (gneisses) were observed. Along the Uelle, from Bima to Bomokandi, the same rocks were seen. In the centre of the region mica-schists, quartzites, and similar metamorphic rocks replace the granite wholly or in part. A noticeable feature here is the presence of a range of isolated hills, composed almost completely of great beds of magnetite and haematite occurring in the schistose series. In the south-eastern portion of the region visited, between the Uelle-Kimbali and Bomokandi rivers, a great plutonic massif is laid bare in the mountainous district of Arebi. The plutonic massif itself contains microclinic gneiss, and abundant diabasic rocks, and the same rocks in all stages of dynamo-metamorphism. On the boundary between the Congo State and the Bahr-el-Ghazal, several hills made up of rocks of coarse gneissose and schistose character are described; some of these rocks are rich in tourmaline, kyanite, and garnet in large crystals. From the region of the Enclave de Lado and the western side of the Nile between Lado and Dufile, mica-schists, quartzites, and microcline-gneisses are described. The alluvium of a large part of the Uelle is covered, on the higher ground, by a deposit of limonitic conglomerate; in places this may be due to the decomposition in situ of the alluvium, but in the neighbourhood of the iron-mountains a sort of passage may be seen between a conglomerate of fresh iron-ores and the more general type of limonitic conglomerate (laterite?).
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Societies and Academies . Nature 72, 46–48 (1905). https://doi.org/10.1038/072046b0
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DOI: https://doi.org/10.1038/072046b0