"Such As South Africa Is Now, Such Have Been Her Main Features
During Countless Past Ages Anterior To The Creation
Of the human race;
for the old rocks which form her outer fringe unquestionably circled round
an interior marshy or
Lacustrine country, in which the Dicynodon flourished,
at a time when not a single animal was similar to any living thing
which now inhabits the surface of our globe. The present
central and meridian zone of waters, whether lakes or marshes,
extending from Lake Tchad to Lake 'Ngami, with hippopotami on their banks,
are therefore but the great modern residual geographical phenomena
of those of a mesozoic age. The differences, however,
between the geological past of Africa and her present state are enormous.
Since that primeval time, the lands have been much elevated
above the sea-level - eruptive rocks piercing in parts through them;
deep rents and defiles have been suddenly formed in the subtending ridges
through which some rivers escape outward.
"Travelers will eventually ascertain whether the basin-shaped structure,
which is here announced as having been the great feature
of the most ancient, as it is of the actual geography of South Africa
(i.e., from primeval times to the present day), does, or does not,
extend into Northern Africa. Looking at that much broader portion
of the continent, we have some reason to surmise that the higher mountains
also form, in a general sense, its flanks only." - President's Address,
Royal Geographical Society, 1852, p. cxxiii.
-
The characteristics of the rainy season in this wonderfully humid region
may account in some measure for the periodical floods of the Zambesi,
and perhaps the Nile. The rains seem to follow the course of the sun,
for they fall in October and November, when the sun passes over this zone
on his way south. On reaching the tropic of Capricorn in December, it is dry;
and December and January are the months in which injurious droughts
are most dreaded near that tropic (from Kolobeng to Linyanti).
As he returns again to the north in February, March, and April, we have
the great rains of the year; and the plains, which in October and November
were well moistened, and imbibed rain like sponges, now become supersaturated,
and pour forth those floods of clear water which inundate
the banks of the Zambesi. Somewhat the same phenomenon probably causes
the periodical inundations of the Nile. The two rivers rise
in the same region; but there is a difference in the period of flood,
possibly from their being on opposite sides of the equator.
The waters of the Nile are said to become turbid in June;
and the flood attains its greatest height in August, or the period
when we may suppose the supersaturation to occur. The subject is worthy
the investigation of those who may examine the region
between the equator and 10 Deg. S.; for the Nile does not show much increase
when the sun is at its farthest point north, or tropic of Cancer,
but at the time of its returning to the equator, exactly as in the other case
when he is on Capricorn, and the Zambesi is affected.*
-
* The above is from my own observation, together with information
derived from the Portuguese in the interior of Angola; and I may add
that the result of many years' observation by Messrs.
Enter page number
PreviousNext
Page 380 of 572
Words from 202968 to 203527
of 306638
