562 Notices of Memoirs—W. Giibson—Geology of East Africa. 
derived from a submerged ridge, of which the Seychelles Islands are 
a remnant. 
The coral rock rests on a sedimentary series consisting of shales, 
limestones, flaggy sandstones, grits, and conglomerates in descending 
order. The beds dip gently to the east. They extend inland to the 
borders of the Taru Plain, a distance of about forty-seven miles. 
The beds are of marine origin, Ammonites and Ichthyosaurian 
remains having been found near Rabai and other localities. 
It is impossible to correlate these beds with any occurring in 
South Africa, but they appear to form a belt running many miles 
north and south of Mombasa. 
The sedimentary beds rest unconformably on a metamorphic 
series, consisting of gneisses, schists, and intrusive granites. The 
strike is N.N.W. and 8.S.E., and the dip is generally high. The 
beds are often intensely folded (Ndange River). LBiotite is the com- 
monest mica, and orthoclase the predominant felspar. ‘The schists 
contain much cyanite, full of iron inclusions. Common garnets are 
plentiful. Hornblendic rocks are remarkably scarce, the main mass 
being micaceous. Graphite schists occur, and the Bura Hills are 
largely composed of a crystalline limestone containing scales of 
graphite. No fossils could be detected. Quartz veins and quartzites 
are only feebly developed. They form gently undulating country 
or else nearly level plains (Taru, Serengeti) through which low 
isolated hills of gneiss and granite protrude. 
It is evident that they have suffered enormous denudation. They 
no doubt represent a complex metamorphosed series of sediments 
and intrusive rocks, but of what. geological age or ages it is 
impossible to state. 
The intrusive granites are generally pegmatites. Porphyritic 
granite covers a large area in Kavirondo. Biotite is the essential 
mica, and a pink orthoclase the predominant felspar. The relation 
of this large mass of granite to the gneisses and schists could 
not be ascertained. 
The area covered by granite and metamorphic rocks is enormous. 
Fully two-thirds of Central Hast Africa are composed of these rocks. 
The remaining portion of the country, excepting the narrow coast 
belt of sedimentary rocks, is formed of recent volcanic rocks. 
No traces of the fossiliferous sandstones and shales found by 
Professor Drummond near Lake Tanganyika, and quite recently by 
Mr. Joseph Thomson to the west of Lake Nyassa and around Lake 
Bangweolo, were detected. If further investigation proves their 
absence from Hast Africa to be a fact, then we have in the deposits 
around Lake Tanganyika the most northerly extension of the 
Karoo beds of South Africa. 
Volcanic rocks form the grandest scenery in Hast Africa. They 
occur in two forms, giving rise to two distinct types of scenery. 
They have either built up tall isolated mountains like Kilimanjaro 
(19,718 ft.), Kenia (18,000 ft.), Elgon (14,000 ft.), Chibchangani 
(12,000 ft.), besides numerous other smaller hills, or they are 
arranged in lines running north and south. The lavas, tuffs, and 
