618 THE FRESH- WATER LOCHS OF SCOTLAND 
obtained by Moore in 1899 off the high western shore, in latitude 
11" 40' South. A more complete series of soundings, however, since 
made by Lieutenant Rhoades,^ gives 386 fathoms (2316 feet) off the 
same coast, in latitude 11° 10' South. The lake is bordered by three 
old beach terraces, of which the most marked lies 14 feet above the 
present water-level. Moore ^ considers that in all probability the 
wearing away of the floor of the Murchison Falls, over which the 
Shire River carries the surplus waters of the lake, led to the lowering 
of the water-level. He says that Nyasa may at one time have been 
connected with Lake Shirwa, and both lakes have drained down the 
valley of the Lujenda River to the Indian Ocean. 
In 1895 and 1899 observations were made on the fauna of Lake 
Nyasa by the Tanganyika expeditions, and it was discovered that 
beyond 100 to 150 feet the lake was practically a fresh- water desert, 
there being encountered in its deeper water nothing but organic refuse 
mixed with fine grey mud. 
Lake Malombe, through which the Upper Shire flows after leaving 
Lake Nyasa, had an area of 100 square miles in 1893, but in 1894 
and the succeeding years a large sand island was thrown up in the 
centre and became covered with reeds, so that in 1896 the lake was 
little more than a broad channel of the Shire River divided by the 
island from a narrower channel to the west. Sir H. Johnston^ 
attributes much of the recent decrease in the volume of the African 
lakes to a slow and gradual upheaval of the land, and he thinks that 
the sudden change of this lake into a sandy marsh and broad river- 
channel supports his view. 
Lakes of the Lake Natroil, 1996 feet above sea-level, in lat. 2^*5 S., long. 
Great Rift ^6° E., is fed by streams from the west side of the rift and by 
other Inland i^u"^^i"ous Small streams impregnated with carbonate of soda. In 
Drainage 1903 Captain C. E. Smith* found it to be only 10 square miles in 
East Africa, extent, but after the January and February rains it had spread over 
about 200 square miles of flats. 
Lake Magadi, 2050 feet above sea-level, in lat. l°-8 S., long. 
36° E., receives one small stream of fresh water and two hot streams 
saturated with sodium carbonate. The lake is some 100 square miles 
in extent, and never more than a few inches deep. It forms a 
natural evaporating pan, and the soda dug from it is remarkably 
pure and abundant. Thousands of flamingoes and wading birds 
1 See Geogr. Journ., vol. xx. p. 68, 1902, 
2 The Tafiganyika Problem, p. 122. 
3 See British Central Africa, London, 1897. 
4 See "From the Victoria Nyanza to Kilimanjaro," Geogr. Journ., vol. xxix. 
p. 258, 1907. 
