OLDUVAI GORGE
LOCATION
A 30-km-long dry canyon in the Serengeti Plains of
northern Tanzania, centered at some 160 km NW of
Arusha, and adjacent to Ngorongoro Crater.
DISCOVERY
Expedition of H. Reck, 1913 (OH 1); L. Leakey and
co-workers, 1935 (OH 2); L. and M. Leakey
and co-workers, 1955-1972 (OH 3-42); M. Leakey
and co-workers, 1973-1982 (OH 43-61); D. Johan-
son and others, 1986 (OH 62); R. Blumenschine and
others, 1993-present (OH 63,64).MATERIAL
Remains (ranging from isolated teeth and cranial or
postcranial fragments to largely complete crania and
skeletons) of over 60 hominid individuals (OH 1-64)
spanning almost 2 million years. Olduvai hominids
include fossils attributed to both Paranthropus and
Homo spp. See Day (1986) for a complete listing (with
specific localities) up to 1982 (OH 61).DATING AND STRATIGRAPHIC CONTEXT
The walls of the Gorge expose a long sequence of
latest Pliocene to latest Pleistocene lacustrine and
fluviatile strata, dated to between 1.9 and 0.01 Ma.
These deposits record complex local changes in
depositional history, and refinement of the Gorge’s
stratigraphy is still continuing. Intermittent local
volcanic activity has, however, permitted K/Ar
dating of a sequence of marker beds, unfortunately
mostly confined to Bed I. The most recent synthesis
of the geology of Olduvai is by Hay (1990), whence
the details given below are taken, modified according
to new Bed I dating by Walter et al. (1991) and the
revised magnetostratigraphy of Tamrat et al. (1995).
The lowest sediments exposed in the Gorge are
those of Bed I, laid down in a shallow alkaline lake and
its tributary streams; the hominid-yielding deposits of
middle and upper Bed I are dated from around 1.9 to
1.75 Ma. The more important Homo or putatively
Homo specimens of this short period include the OH 7
mandible/parietals/hand bones, holotype of Homo
habilis; the OH 8 foot, paratype; the OH 24 fragmen-
tary cranium; the OH 62 fragmentary skeleton; and
the OH 64 palate. Sedimentation of this kind con-
tinued through Bed I1 times, about 1.75-1.4 Ma,
although faulting dramatically reduced the size of the
lake at about 1.6 Ma. Notable Bed I1 Homo specimens
include the OH 13 fragmentary skull, a paratype of
Homo habilis (probably about 1.6-1.5 Ma); the slightly
older and even more fragmentary skull OH 16; and
the much larger-brained OH 9 calvaria, now thought
to date from around 1.5-1.4 Ma. Beds 111 and IV are
usually considered together, since they are often hard
to distinguish lithologically. Jointly they span about
1.4 Ma to perhaps 1.0 Ma, although the latter date
could vary by as much as about 0.2 Ma. Bed 111 sedi-
ments have yielded scattered artifacts but no diagnostic
hominid fossils, while Bed IV has produced specimens194