SEDIMENTOLOGY OF THE MALAWI RIFT - FACIES AND STRATIGRAPHY OF THE CHIWONDO BEDS, NORTHERN MALAWI

Shallow water, nearshore lake beds and fluviatile deposits exposed in the Karonga District (northern Malawi) are subdivided into several depositional units which are bounded by unconformities reflecting sedimentary breaks. Prior to the formation of a major perennial lake which also flooded the area studied, sedimentation was characterized by extensive fluviatile deposits mainly formed by reworked material of Jurassic red beds. Formation of a major lake after this episode is reflected by widespread lacustrine silts and sands with interbedded, mollusc-rich layers. Tectonic reorganization of the rift finally led to localized uplift resulting in an angular unconformity and exposure of the Plio-Pleistocene deposits. The hominid fossil at Uraha Hill occurs in an interchannel or swamp-related alluvial setting.