Lake Nyasa is a narrow trough, 360 miles long, between mountain-ranges which hem it in closely on the west (sending down, during the rains, innumerable small torrents from their steep slopes), and retreat somewhat from it on the east, leaving room for a few larger, but still inconsiderable streams, such as the Songwe, the Rukuru, the Bua, and one or two more. The Shiré is the lake’s only outlet, flowing through a level alluvial valley (something like a delta reversed) till, a little below Matope, it comes to the edge of the plateau and plunges over in a series of falls known as the Murchison Cataracts. These extend over forty miles of river, and make a difference in its level of some 1200 feet, though none of them, individually, are of any great height. The level of the lake, and consequently of the river which it feeds, is very different at different seasons of the year. During the rains, and for some time after, steamers can go to the foot of the Murchison Cataracts—the usual terminus is Katunga’s, about twelve miles below them. In the dry season they cannot always come within sight of Chiromo, and, during the great drought of 1903, the natives of that place were hoeing their maize-gardens far out in the channel of the river. The salt Lake Chilwa, east of the Shiré, disappeared almost, if not quite, at that time, but reappeared with subsequent rains. It is thought, however, that there is a continuous fall in the level of Nyasa, which is unaffected by the rise and fall of successive seasons. In some places a series of old beaches can be traced, ascending like terraces from the lake-shore to the foot-hills. This fall is attributed to several causes—the wearing away of the outlet channel, allowing more water to escape; the disappearance of the forests and consequent diminution of the rainfall; and the raising of the ground by volcanic action. There are not now any active volcanoes in the country, but earthquakes are common in the neighbourhood of the lake, and there are hot springs near Kotakota, and also on Mount Morambala (Lower Shiré). Mlanje Mountain is of volcanic origin; in the German territory, north of Nyasa, there are numerous extinct volcanoes and crater-lakes.