The Geology of the Ruhuhu Coalfields, Tanganyika Territory

Abstract

I. Introduction From June to October of 1930 it was my good fortune to survey the coalfields of the Njombe and Songea districts of Tanganyika Territory, east of Lake Nyasa; an area of some 1500 square miles, of which 1330 square miles are occupied by Karroo rocks. The coalfields stretch eastwards from the shore of the lake, their eastern boundary being formed by the disused motor-road from Songea township to Njombe; the northern and southern limits are defined by the faulted boundaries of the Karroo formation. The extension of the Karroo rocks beyond the eastern boundary is unknown; it is probable that they continue in a north-easterly direction as far as to the Rufiji River. An account of the coalfields, with especial reference to their economic possibilities, is in course of publication in a Government Bulletin. The description of the geology given in the present paper will serve as an introduction to the papers dealing with the palæontology of the Karroo rocks. Very little work had been done in this area previously, although German geologists had determined roughly the extent of the Karroo formation. Bornhardt (1900), the first geologist to visit the district, had examined a coalfield south of Manda in 1895-7 and condemned it. His observations are summarized by Koert (1913, pp. 195-6, translation) as follows:— ‘Bornhardt speaks of the Ruhuhu as a tableland intersected by faults, and divides up its beds as follows:— River depression. The following were identified in the collection:— (i) Petrified Fossil Wood from the