| dc.description.abstract | The study examines in detail an area between Mount Longonot in the east tthrough
Lake Naivasha Basin to Mount Eburru in the west. The result is a model of major
occurrences of obsidian quarry sources that may have been mined by prehistoric
man as quarry sources of raw material for the production and/or making of his
tools (artifacts). By combining this model, derived mainly from physical data in
the field with that deduced essentially from chemical data in the laboratory, the
obsidian outcrops have been categorized into major petrological groups. This
enables questions about the origin, area of recharge and availability of magma to
be discussed The initial sections are concerned with the physical geology of the
study area incorporating faulting and physiography as possible contributors to the
formation of obsidian. The section on geochemistry deals' with geochemical
manifestations together with information on the temporal evolution of the crust
that is considered to be the source of the obsidian in the Naivasha area. The
approach thus discusses and reviews both the petrographic and geochemical
features in order to establish magmatic trends and the possible transitional stages
involved. Using relative coneentrations of both major and trace elements
determined by x - ray fluorescence analysis, the various sources are separated and
assigned to individual petrographic groups within the study area.
Obsidian occurrences from several quarry sources within this general area are
described including their geochemistry. Geochemical results suggest possibility of
extreme interaction and assimilation with the crust in the 'secondary' volcanic
feeder chambers. The associated rocks encountered, are limited to volcanic lava
flows and pyroclastics of the central rift system. Faulting. a major structural
feature in the area IS described and later considered as a possible major
contributor to the development and distribution of obsidian outcrops although
some of the faults have been covered by late stage volcanic activity together with
weathering.
To derive such information as distance and pc.-sible areas of mining during
prehistoric times, an attempt is made to correlate artifacts from four widely
separated Archeological Sites at Narosura in Kajiado and Gogo Falls in South
Nyanza, Jawuoyo in Kisurnu and Cartwright's site located on the Kinangop
Escarpment. Merrick and Brown (1984a) have suggested that such studies can
lead to an insight regarding authenticity, trade routes and trading connections and
other features of historical and archeological interest.
This study was conducted to fulfiJJ the requirements for a Master of Scicnc degree
at the Lniversity of Nairobi. Special thanks go 1O Dr. Mohamed Ishahakia,
Director Chief Executive, National Museums of Kenya and Ms. Jackie Davies, past
Chairperson, Kenya Museum Society. Thanks are also due to my Supervisors.
Professor Isaac Nyambok and Dr. Benson Mboya both of the Geology Department
and Mr. Antony Muriithi Kinyua of the Institute of Nuclear Science, for their
discussions and suggestions. The Late Mr. Wevva of the Geology Department
helped with the thin section preparations. The Director's Office. National Museums
of Kenya, Professor Hidemi Ishida. Kyoto University Japan and the Kenya
Museum Society funded the fieldwork. The Department of Geology, University of
Nairobi and the National Museums of Kenya prov idcd Field facilities. Laboratory
analyses were carried out at the Faculty of Science. Department of Geology and
F aculty of Engineering, Institute of Nuclear Science.
Finally, special thanks are due to Plummy and Stacey for so much encouragement. | en |
