CHAR AC I ERISTICS AND DISTRIBUTION OF LAKES 617 
with the Jurassic sea to have been in the west and north-west, through 
the basin of the Congo. According to Cunnington, this theory is 
supported neither by geological nor palaeontological evidence, and he 
considers that in the present state of our knowledge it is impossible 
to put forward a convincing theory that will fit the facts of the case. 
Lake Kivu lies at an altitude of about 4829 feet above sea- 
level, about 100 miles north of Lake Tanganyika, into which it 
drains. The lake is 60 miles long by 30 to 40 miles broad, and more 
than 600 feet deep ; the area, including islands, is about 1100 square 
miles. It is roughly triangular in outline, the longest side lying to 
the west. Its waters are charged with saline matter to such an 
extent that the shores have become incrusted with a substance con- 
taining a high percentage of magnesium carbonate. Samples of this 
incrustation were examined under the direction of Professor Wynne, 
and only traces of calcium salts were found to be present. A 
calcareous tufa is found on the lake-floor deposited round vegetable 
debris, and also incrusting pebbles and reed-stems on the shore-line. 
The nodular incrustation is very hard, and was found on analysis to 
contain 28*65 per cent, calcium oxide and 12*66 per cent, magnesium 
oxide} 
Lake Leopold II. is described by Stanley ^ as a shallow depression 
in the lowland portion of the Congo basin caused by sudden subsidence. 
It discharges by the Ufini River into the Kasai, a tributary of the 
Congo. 
Stanley Pool is an expansion of the Congo, about 25 miles 
long by 16 miles broad. The pool is a great cup-like basin with an 
incomplete rim formed by sierras of peaked mountains ranging on 
the southern side from 1000 to 3000 feet in height. The pool 
contains seventeen islands of some note. 
Lake Nyasa. — The only great lake of this system, Lake Nyasa, River Zambesi, 
drains into the Zambesi by the Shire River. It extends from 9° 29' to 
14° 25' South, or through nearly 5 degrees of latitude, and measures 350 
miles along its major axis, which is slightly inclined to the west of 
north, while the greatest breadth, occurring near the middle of its 
length, is 45 miles. The total area is 14,200 square miles. It lies 
in a very long and relatively narrow valley, the surface of the lake, 
which is 1645 feet above sea-level, being far below the general level 
of the surrounding country. The depth of the lake seems to vary in 
accordance with the steepness of the shores, increasing from south to 
north. The greater part of the northern half shows depths of over 
200 fathoms, while a maximum depth of 430 fathoms (2580 feet) was 
^ See Moore, The Tanganyika Problem, p. 84, London, 1903. 
2 See The Congo and the Founding of its Free State, pp. 435 et seq., London, 1885. 
