Geology of the Malawi Rift

In co-operation with our Malawian partners of the Antiquities Department in Lilongwe, the HCRP started in 1983 to search for fossil-bearing strata, first on a geological map. On the basis of satelite pictures and geological reports that dated back to colonial times, we localized our future site.

The origin of those fossil sites is bound to local geological conditions. Only if a depositional area is available where decayed or transported skeletal remains are covered by sediments and are therefore protected from further destruction, the process of fossilization may occur.. Potentially good regions for sedimentation are large, slowly descending basins such as in the East African Rift Valley that formed by the drift of the continental earth’s crust. Often, fragments of former organisms were embedded in the sands that were transported by rivers, and with increasing cover, such as in delta areas, they fossilize. These fossils are today accessible because quite recently in geological history uplifts occurred. The strata lying on the surface today are eroded by rivers so that the fossils emerge.



Important for our first basic work on the geological history of the Malawi Rift were Uwe Ring, our specialist for tectonics, and Christian Betzler, our sedimentologist. All sites were thus explored sedimentologically and tectonically. For the dating of the fossils, their original position in the geological strata had to be reconstructed. The stratigraphy at the site is determined by geological profiles and displays the formation of the geological strata. Then the original deposit area throughout a certain timespan can be ascertained. The Malawi Rift was formed 8 million years ago and abundant fossil remains of shells and fish leave no doubt that there existed a very early version of Lake Malawi.

We presumed that this Rift Valley was the most narrow trail for the Hominids between the main sites of specimens of the genus Homo that are a long way away from each other. Because we wanted to reconstruct the changes in the environment and the fauna as well as the pathways of the dispersion, there was no alternative for the Malawi Rift, the preservation and the quantity of fossils being as poor as they were. Both became clear in our first campaign: the fossils were mostly very fragmented because at the time of their embedding, the Rift Valley was narrow and steep, but they provide important insights into the biogeography and the role of the climate change for the evolution of man.