The tendency and spirit of the age are more and more towards the undertaking of industrial enterprises of such magnitude and skill as to require the capital of the world for their support and execution—as the Pacific Railroad, Suez Canal, Mont Cenis Tunnel, and railways in India and Western Asia, Euphrates Railroad, &c. The extension and use of railroads, steamships, telegraphs, break down nationalities and bring peoples geographically remote into close connection commercially and politically. They make the world one, and capital, like water, tends to a common level.
[Geologists will be glad to find that the Doctor took pains to arrange his observations at this time in the following form.]
A really enormous area of South Central Africa is covered with volcanic rocks, in which are imbedded angular fragments of older strata, possibly sandstone, converted into schist, which, though carried along in the molten mass, still retain impressions of plants of a low order, probably the lowest—Silurian—and distinct ripple marks and raindrops in which no animal markings have yet been observed. The fewness of the organic remains observed is owing to the fact that here no quarries are worked, no roads are made, and as we advance north the rank vegetation covers up everything. The only stone buildings in the country north of the Cape colony are the church and mission houses at Kuruman. In the walls there the fragments, with impressions of fossil leaves, have been broken through in the matrix, once a molten mass of lava. The area which this basalt covers extends from near the Vaal River in the south, to a point some sixty miles beyond the Victoria Falls, and the average breadth is about 150 miles. The space is at least 100,000 square miles. Sandstone rocks stand up in it at various points like islands, but all are metamorphosed, and branches have flowed off from the igneous sea into valleys and defiles, and one can easily trace the hardening process of the fire as less and less, till at the outer end of the stream the rocks are merely hardened. These branches equal in size all the rocks and hills that stand like islands, so that we are justified in assuming the area as at least 100,000 square miles of this basaltic sea.
The molten mass seems to have flowed over in successive waves, and the top of each wave was covered with a dark vitreous scum carrying scoriæ with angular fragments. This scum marks each successive overflow, as a stratum from twelve to eighteen inches or more in thickness. In one part sixty-two strata are revealed, but at the Victoria Falls (which are simply a rent) the basaltic rock is stratified as far as our eyes could see down the depth of 310 feet. This extensive sea of lava was probably sub-aerial, because bubbles often appear as coming out of the rock into the vitreous scum on the surface of each wave: in some cases they have broken and left circular rings with raised edges, peculiar to any boiling viscous fluid. In many cases they have cooled as round pustules, as if a bullet were enclosed; on breaking them the internal surface is covered with a crop of beautiful crystals of silver with their heads all directed to the centre of the bubble, which otherwise is empty.
These bubbles in stone may be observed in the bed of the Kuruman River, eight or ten miles north of the village; and the mountain called "Amhan," west-north-west of the village, has all the appearance of having been an orifice through which the basalt boiled up as water or mud does in a geyser.
The black basaltic mountains on the east of the Bamangwato, formerly called the Bakaa, furnish further evidence of the igneous eruptions being sub-aerial, for the basalt itself is columnar at many points, and at other points the tops of the huge crystals appear in groups, and the apices not flattened, as would have been the case had they been developed under the enormous pressure of an ocean. A few miles on their south a hot salt fountain boils forth and tells of interior heat. Another, far to the south-east, and of fresh water, tells the same tale.
Subsequently to the period of gigantic volcanic action, the outflow of fresh lime-water from the bowels of the earth seems to have been extremely large. The land now so dry that one might wander in various directions (especially westwards, to the Kalahari), and perish for lack of the precious fluid as certainly as if he were in the interior of Australia, was once bisected in all directions by flowing streams and great rivers, whose course was mainly to the south. These river beds are still called by the natives "melapo" in the south, but in the north "wadys," both words meaning the same thing, "river beds in which no water ever now flows." To feed these a vast number of gushing fountains poured forth for ages a perennial supply. When the eye of the fountain is seen it is an oval or oblong orifice, the lower portion distinctly water worn, and there, by diminished size, showing that as ages elapsed the smaller water supply had a manifestly lesser erosive power. In the sides of the mountain Amhan, already mentioned, good specimens of these water-worn orifices still exist, and are inhabited by swarms of bees, whose hives are quite protected from robbers by the hardness of the basaltic rocks. The points on which the streams of water fell are hollowed by its action, and the space around which the water splashed is covered by calcareous tufa, deposited there by the evaporation of the sun.
Another good specimen of the ancient fountains is in a cave near Kolobeng, called "Lepélolé," a word by which the natives there sometimes designate the sea. The wearing power of the primeval waters is here easily traced in two branches—the upper or more ancient ending in the characteristic oval orifice, in which I deposited a Father Mathew's leaden temperance token: the lower branch is much the largest, as that by which the greatest amount of water flowed for a much longer period than the other. The cave Lepélolé was believed to be haunted, and no one dared to enter till I explored it as a relief from more serious labour. The entrance is some eight or more feet high, and five or six wide, in reddish grey sandstone rock, containing in its substance banks of well rounded shingle. The whole range, with many of the adjacent hills on the south, bear evidence of the scorching to which the contiguity of the lava subjected them. In the hardening process the silica was sometimes sweated out of this rock, and it exists now as pretty efflorescences of well-shaped crystals. But not only does this range, which stands eight or ten miles north of Kolobeng, exhibit the effects of igneous action, it shows on its eastern slope the effects of flowing water, in a large pot-hole called Löe, which has the reputation of having given exit to all the animals in South Africa, and also to the first progenitors of the whole Bechuana race. Their footsteps attest the truth of this belief. I was profane enough to be sceptical, because the large footstep of the first man Matsieng was directed as if going into instead of out of this famous pot-hole. Other huge pot-holes are met with all over the country, and at heights on the slopes of the mountains far above the levels of the ancient rivers.
Many fountains rose in the courses of the ancient river beds, and the outflow was always in the direction of the current of the parent stream. Many of these ancient fountains still contain water, and form the stages on a journey, but the primitive waters seem generally to have been laden with lime in solution: this lime was deposited in vast lakes, which are now covered with calcareous tufa. One enormous fresh-water lake, in which probably sported the Dyconodon, was let off when the remarkable rent was made in the basalt which now constitutes the Victoria Falls. Another seems to have gone to the sea when a similar fissure was made at the falls of the Orange River. It is in this calcareous tufa alone that fossil animal remains have yet been found. There are no marine limestones except in friths which the elevation of the west and east coasts have placed far inland in the Coanza and Somauli country, and these contain the same shells as now live in the adjacent seas.
Antecedently to the river system, which seems to have been a great southern Nile flowing from the sources of the Zambesi away south to the Orange River, there existed a state of fluvial action of greater activity than any we see now: it produced prodigious beds of well-rounded shingle and gravel. It is impossible to form an idea of their extent. The Loangwa flows through the bed of an ancient lake, whose banks are sixty feet thick, of well-rounded shingle. The Zambesi flows above the Kebrabasa, through great beds of the same formation, and generally they are of hard crystalline rocks; and it is impossible to conjecture what the condition of the country was when the large pot-holes were formed up the hillsides, and the prodigious attrition that rounded the shingle was going on. The land does not seem to have been submerged, because marine limestones (save in the exceptional cases noted) are wanting; and torrents cutting across the ancient river beds reveal fresh-water shells identical with those that now inhabit its fresh waters. The calcareous tufa seems to be the most recent rock formed. At the point of junction of the great southern prehistoric Nile with an ancient fresh-water lake near Buchap, and a few miles from Likatlong, a mound was formed in an eddy caused by some conical lias towards the east bank of this rent within its bed, and the dead animals were floated into the eddy and sank; their bones crop out of the white tufa, and they are so well preserved that even the black tartar on buffalo and zebra's teeth remain: they are of the present species of animals that now inhabit Africa. This is the only case of fossils of these animals being found in situ. In 1855 I observed similar fossils in banks of gravel in transitu all down the Zambesi above Kebrabasa; and about 1862 a bed of gravel was found in the delta with many of the same fossils that had come to rest in the great deposit of that river, but where the Zambesi digs them out is not known. In its course below the Victoria Falls I observed tufaceous rocks: these must contain the bones, for were they carried away from the great tufa Lake bottom of Seshéké, down the Victoria Falls, they would all be ground into fine silt. The bones in the river and in the delta were all associated with pieces of coarse pottery, exactly the same as the natives make and use at the present day: with it we found fragments of a fine grain, only occasionally seen among Africans, and closely resembling ancient cinerary urns: none were better baked than is customary in the country now. The most ancient relics are deeply worn granite, mica-schist, and sandstone millstones; the balls used for chipping and roughing them, of about the shape and size of an orange, are found lying near them. No stone weapons or tools ever met my eyes, though I was anxious to find them, and looked carefully over every ancient village we came to for many years. There is no flint to make celts, but quartz and rocks having a slaty cleavage are abundant. It is only for the finer work that they use iron tongs, hammers, and anvils and with these they turn out work which makes English blacksmiths declare Africans never did. They are very careful of their tools: indeed, the very opposites to the flint implement men, who seem sometimes to have made celts just for the pleasure of throwing them away: even the Romans did not seem to know the value of their money.