an engineering geological characterisation of tropical clays - GBV

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possible use as building stone and in the manufacture of bricks and tiles, limes and cements.
His findings were published in a report issued by the Imperial Institute (1926).
Bailey Willis (1936) described the Kikuyu scarp to the west of Nairobi, the warped peneplain
around Nairobi and the grid – faulting that has affected the volcanic rocks of the Rift valley
region and western parts of Nairobi area. Saggerson and Baker (1965) also investigated and
described, among others, the Kikuyu scarp and the warped peneplain in the neighbourhood of
Nairobi area.
Campbell Smith (1931) described and classified the trachytes and phonolites of Nairobi and
its surroundings after examining and analysing a number of rock specimens collected from the
areas. His findings were published and incorporated in a report.
Bowen visited Kenya in the 1930´s and made an excursion into the Rift Valley. He also
collected specimens of volcanic rocks from other parts of the country, including Nairobi and
the present study area. In 1937, he published the results of his studies in a paper in which he
illustrated his experimental work with personal observations on the lavas.
The nature of alkali – feldspars in certain Kenyan rocks, including the Kapiti phonolite was
investigated by Häkli (1960). The specimens of Kapiti phonolite had been previously
collected by a Finnish Expedition in 1952 from the Stony Athi River and Nairobi, including
some parts of the study area.
Williams (1967) outlined the geology of Nairobi and its surroundings, in its regional setting.
Various lavas have also been collected from the Nairobi succession and dated (Baker et al,
1988). Curtiss, Evernden and Miller of the University of California, USA, carried out K/Ar –
age dating on rock specimens collected from the Nairobi region. The volcanic rocks were
found to be Upper Miocene to Pleistocene in age (Evernden et al, 1964).
Other studies involving Nairobi and covering the present study area include palaeomagnetic
studies by staff of the Department of Physics, University of Nairobi (Mussett et al, 1964-
1965); and the monitoring and detection of seismic activities and possible associated earth
movements, by the Seismology Section, Department of Geology, University of Nairobi
(1990-2002).
A number of other geological investigations have been carried out in Nairobi and its environs,
including the study area; but they are recorded as unpublished works by the Mines and
Geological Department, Nairobi. Some of the unpublished works include those of Binge,
Joubert, Pulfrey and Saggerson (Mines and Geological Department, Nairobi, 2001).
Early works regarding detailed survey and study of soils of the Nairobi area and its environs
were undertaken by Jones in 1952 and published in 1953. His works were later carried
forward to completion by Scott, of the then East African Agriculture and Forestry Research
Organisation. In his works, he described a variety of soils found as having developed under a
wide range of climatic conditions (Scott, 1963).
Other works in the study of soils were undertaken by Stephen, Bellis and Muir (1956), who
investigated the nature of the black cotton soils overlying Nairobi phonolite in the Athi
plains, with the purpose of establishing the cause for uneven growth of crops. They also noted
that soils from Embakasi area, Nairobi, contained some minerals typical of metamorphic
rocks.