Type Geological formation Underlies None Country Tanzania | Unit of Songea Group Region Ruhuhu Basin Overlies Usili Formation | |
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Sub-units Kingori Sandstone Member, Lifua Member | ||
The Manda Formation (also known as the Manda Beds) is a Middle Triassic geologic formation in Tanzania. It preserves fossils of many terrestrial vertebrates from the Triassic, including some of the earliest archosaurs.
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History of study
One of the first to study rocks of the Manda Formation was British geologist G. M. Stockley. In 1932, Stockley explored the geology of the Ruhuhu Basin in Tanzania. He called a series of layers dating from the Late Carboniferous to the Middle Triassic the Songea Series and divided it into eight units labelled K1-K8. Stockley was also the first to describe fossils from these rocks, naming an older layer the "Lower Bone Bed" and a younger layer the "Upper Bone Bed".
In 1957, paleontologist Alan J. Charig described many more fossils from the bone beds in his Ph.D. thesis for the University of Cambridge. Charig renamed the youngest of Stockley's units in 1963, calling unit K6 the Kawinga Formation, K7 the Kingori Sandstones, and K8 the Manda Formation. Fossils were identified in many strata, invalidating Stockley's division into two distinct bone beds. Since Charig's description, the Kawinga Formation has been renamed the Usili Formation, the Kingori Sandstones have become the Kingori Sandstone Member of the Manda Formation, and Charig's original Manda Formation has become a subunit of the formation called the Lifua Member. Six formations and one informal unit are currently recognized in the Songea Group (Ruhuhu basin) rocks range in age from Pennsylvanian to Anisian, including the Idusi (K1), Mchuchuma (K2), Mbuyura (K3), Mhukuru (K4), Ruhuhu (K5), and Usili (K6) formations and the informal Manda Beds, which include the Kingori Sandstone (K7) and Lifua Member (K8).