ne now winds in it in an opposite direction to that in which the
ancient river must have flowed.

Both the Lekone and Unguesi flow back toward the centre of the country,
and in an opposite direction to that of the main stream. It was plain,
then, that we were ascending the farther we went eastward. The level of
the lower portion of the Lekone is about two hundred feet above that
of the Zambesi at the falls, and considerably more than the altitude
of Linyanti; consequently, when the river flowed along this ancient
bed instead of through the rent, the whole country between this and the
ridge beyond Libebe westward, Lake Ngami and the Zouga southward, and
eastward beyond Nchokotsa, was one large fresh-water lake. There is
abundant evidence of the existence and extent of this vast lake in
the longitudes indicated, and stretching from 17 Deg. to 21 Deg. south
latitude. The whole of this space is paved with a bed of tufa, more
or less soft, according as it is covered with soil, or left exposed
to atmospheric influences. Wherever ant-eaters make deep holes in this
ancient bottom, fresh-water shells are thrown out, identical with those
now existing in the Lake Ngami and the Zambesi. The Barotse valley was
another lake of a similar nature; and one existed beyond Masiko, and a
fourth near the Orange River. The whole of these lakes were let out by
means of cracks or fissures made in the subtending sides by the upheaval
of the country. The fissure made at the Victoria Falls let out the water
of this great valley, and left a small patch in what was probably
its deepest portion, and is now called Lake Ngami. The Falls of Gonye
furnished an outlet to the lake of the Barotse valley, and so of the
other great lakes of remote times. The Congo also finds its way to the
sea through a narrow fissure, and so does the Orange River in the west;
while other rents made in the eastern ridge, as the Victoria Falls and
those to the east of Tanganyenka, allowed the central waters to drain
eastward. All the African lakes hitherto discovered are shallow, in
consequence of being the mere 'residua' of very much larger ancient
bodies of water. There can be no doubt that this continent was, in
former times, very much more copiously supplied with water than at
present, but a natural process of drainage has been going on for ages.
Deep fissures are made, probably by the elevation of the land, proofs
of which are seen in modern shells imbedded in marly tufa a