stripes
This is a shield volcano with a central crater which is only some 200 m high but 15 km in diameter. Individual aa flows are up to 20 km in length, but close to the crater they may become of pahoehoe type. Columnar structures are present within the crater. The rocks contain olivine phenocrysts in a matrix of plagioclase, pyroxene, olivine, opaques, calcite and zeolite. Four analyses in Vail (1973) indicate that the rocks are tephrite, basanite and trachybasalt.
BARTH, H. and MEINHOLD, K.-D. 1979. Mineral prospecting in the Bayuda Desert. Part 1, Volume A. Investigation of mineral potential. Technical Report Sudanese-German Exploration Project. Hannover (Bundesanstalt fur Geowissenschaften und Rohstoffe). 336 pp. (unpublished) VAIL, J.R. 1973. Jebel Umm Marafieb: an extinct volcano near Berber. Sudan Notes and Records, 54: 188-92.VAIL, J.R. 1990. Geochronology of the Sudan. Overseas Geology and Mineral Resources, London, 66: 1-58.
