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The Olduvai Gorge or Oldupai Gorge
is commonly referred to as "The Cradle of
Mankind." It is a steep-sided
ravine in the
Great Rift Valley, which stretches along
eastern Africa. Olduvai is in the eastern
Serengeti Plains in northern
Tanzania and is about 30 miles long. The
gorge is named after the
Maasai word for the wild sisal plant
Sansevieria ehrenbergii, commonly called
Oldupaai.
It is one of the most important prehistoric
sites in the world and has been instrumental in
furthering understanding of early
human evolution. Excavation work there was
pioneered by
Louis and
Mary Leakey in the 1950s and is continued
today by their family. Millions of years ago,
the site was that of a large lake, the shores of
which were covered with successive deposits of
volcanic ash. Around 500,000 years ago seismic
activity diverted a nearby stream which began to
cut down into the
sediments, revealing seven main layers in
the walls of the gorge.
The
stratigraphy is extremely deep and layers of
volcanic ashes and stones allow
radiometric dating of the embedded
artifacts, mostly through
potassium-argon dating. The first
artifacts in Olduvai (pebble
tools and
choppers) date to circa 2 million years ago
but
fossil remains of human ancestors have been
found from as long as 2.5 million years ago.
The earliest archaeological deposit, known as
Bed I, has produced evidence of campsites and
living floors along with
stone tools made of
flakes from local
basalt and
quartz. Since this is the site where these
kinds of tools were first discovered, these
tools are called
Oldowan. It is now thought that the Oldowan
tool making tradition started about 2.6 million
years ago. Bones from this layer are not of
modern humans but primitive
hominid forms of
Paranthropus boisei and the first
discovered specimens of
Homo habilis.
The Olduvai Gorge bears the distinction of
having the oldest known evidence of
mammoth consumption, attributed to
Homo ergaster around 1.8 million years ago.
Above this, in Bed II, pebble tools begin to be
replaced by more sophisticated
handaxes of the
Acheulean
industry and made by
Homo ergaster. This layer dates to around
1.5 million years ago.
Beds III and IV have produced
Acheulean tools and fossil bones with
Neandertal characteristics which were used
until around 600,000 years ago.
During a period of major faulting and volcanism
roughly 400,000 to 600,000 years ago, the Masek
Beds were made.
Beds above these contained tools from a
Kenya-Capsian
industry made by modern humans and are termed
the Masek Beds (600,000 to 400,000 years ago),
the Ndutu Beds (400,000 to 32,000 years ago),
and the Naisiusiu Beds (22,000 to 15,000 years
ago).
Also located on the rim of the Gorge is the
Olduvai Gorge Museum. This Museum presents
exhibitions pertaining to the Gorge's history.
Olduvai is the location of the first
monolith in
Arthur C. Clarke's
2001: A Space Odyssey series of books.
Olduvai is also the theme of the
Olduvai theory, which states that industrial
civilization will have a lifetime of less than
or equal to 100 years.
The variant "Oldupai" is the Maasai word for the
wild Sisal plant that grows in the gorge; some
claim the more common spelling "Olduvai" is the
result of a mis-hearing of the word by colonial
visitors. The latter spelling is not used
locally.
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