Noolchalai is an Early Acheulean site located in a densely vegetated area on the southern hillsides of the Oldoinyo Sambu volcano, in the Northern Escarpment. The site, originally named RHS and Mugulud by Isaac, was discovered and extensively excavated in 1964. Between 1995 and 2002 further research was undertaken. In 2009 our team resumed fieldwork in the Northern Escarpment. Our research is in progress and includes new excavations in the main site, new stratigraphical and geoarchaeological studies in the area, intensive survey and the excavation of new sites discovered. Noolchalai is stratigraphically located in the transition between the Humbu and Moinik Formations. It is a taphonomically complex site. Here, the Moinik Formation, related to the onset of a new alluvial regime, incorporated Humbu materials to braided channels. The first steps of this reworking of Humbu materials include the heaviest and largest lithic specimens of Acheulean assemblages originally deposited at the top of the Humbu Formation.
Despite being located in secondary position, Noolchalai preserves valuable information regarding the technological description of the Early Acheulean at Lake Natron. Main technological traits are comparable with the Early Acheulean described at Lepolosi. Classical Acheulean LCTs, (handaxes, cleavers and trihedral picks) are present in the assemblage, although the bulk of LCTs is constituted by specimens partially transformed in order to repeatedly produce forceful tips and/or strong cutting edges. Currently, we are focused on the excavation of new sites discovered at the vicinity of Noolchalai. Although related to the same post-depositional processes, these sites constitute remarkable accumulations of Acheulean artefacts preserved in better conditions.