The site of Simbiro III is located in the riverbed of a tributary of the Awash, about 4 km from the sites of Garba and Gombore. The limited excavations (Simbiro III1, Simbiro III2a, Simbiro III2b and Simbiro III5) carried out in 1976 and in 2005 at the site allowed four archaeological levels to be identified.
The four archaeological levels, indicated by the letters A, B, C and D, are separated by short time spans and can be attributed to the Early and Middle Acheulean. The lowest levels D is made of sands and pebbles, interrupted by sandy layers mixed with volcanic tuffs, reaching a thickness of 6 m. Layer D corresponds to a fluvial level with a predominance of pebbles of different kinds of volcanic rocks. The level C contains only obsidian industry, characterized by the abundance of the handaxes.
The presence of two species of Bovids should be noted; the first one can be related to Pelorovis sp., while the other suggests probably Pelorovis oldowayensis, a giant form known from Bed II at Olduvai Gorge (Kenya) before 1.2 Myr. Remains of hippopotamus and Suids have also been found at Simbiro.
In level D obsidian flakes with trihedral cross-section and large notches are frequent, but obsidian handaxes can also be found; flakes are instead dominant in level C. Level B yielded most of the lithic artifacts, such as cleavers and handaxes often showing an archaic technology, and obsidian flakes. Worked pebbles made of basalt and volcanic tuff are also associated with this tool kit. A limited excavation of 4 m² carried out in level A yielded hundreds of lithic artifacts and faunal remains. The obsidian handaxes of the level C present a high degree of standardization both in the dimension (length: 13-15 cm) and in the shaping procedures.