Page:EB1911 - Volume 27.djvu/202

 to west its greatest extent is 397 m. The total area is 111,196 sq. m., a little less than the area of Great Britain and Ireland. The boundaries of the Transvaal have varied from time to time. The most important alteration was made in January 1903 when the districts of Utrecht and Vryheid, which then formed the south-eastern part of the country were annexed to Natal. The area thus lost to the Transvaal was 6970 sq. m. (For map see .)

Physical Features.—About five-sixths of the country lies west of the (q.v.), the mountain range which forms the inner rim of the great tableland of South Africa. For a few miles on the Natal–Transvaal frontier the Drakensberg run east and west and here is the pass of Laing’s Nek. Thence the mountains sweep round to the north, with their precipitous outer slopes facing east. For some 250 m. within the province the mountains form a more or less continuous range, the highest point being the Mauchberg (8725 ft.) in 24° 20′ 10″ S. 30° 35′ E., while there are several heights of 7000 or more feet. Eastward from the foot of the Drakensberg stretches a broad belt of low land beyond which rise the Lebombo hills running north and south along the parallel of 32° E. and approaching within 35 m. of the sea at Delagoa Bay. The Lebombo hills are flat topped but with a well-defined break on their seaward side. This eastern edge forms the frontier between Transvaal and Portuguese territory.

The country west of the Drakensberg, though part of the main South African tableland, is not uniform in character, consisting of (1) elevated downs, (2) their slopes, (3) the flat “bottom” land. The downs or plateaus occup all the southern part of the country, sloping gradually westward from the Drakensberg. That part of the plateau east of Johannesburg is from 5000 to 6400 ft. high; the western and somewhat larger half is generally below 5000 ft. and sinks to about 4000 ft. on the Bechuanaland border. This plateau land is called the high veld, and covers about 34,000 sq. m. The northern edge of the plateau follows an irregular line from somewhat north of Mafeking on the west to the Mauchberg on the east. This edge is marked by ranges of hills such as the Witwatersrand, Witwatersberg and Magaliesberg; the Witwatersrand, which extends eastward to Johannesburg, forming the watershed between the rivers flowing to the Atlantic and Indian Ocean. Farther north, beyond the intervening slopes and low bush, are two elevated regions covering together over 4000 sq. m. They are the Waterberg, and, more to the east, separated from the Waterberg by the valley of the Magalakwane tributary of the Limpopo, the Zoutpansberg. The Zoutpansberg has steep slopes and is regarded as the northern termination of the Drakensberg. An eastern offshoot of the Zoutpansberg is known as the Murchison Range. The low land between the high veld and the Waterberg and Zoutpansberg is traversed by the Olifants River, an east flowing tributary of the Limpopo.

The true high veld, extending east to west 120 m. and north to south 100 m., consists of rolling grass covered downs, absolutely treeless, save where, as at Johannesburg, plantations have been made by man, the crest of the rolls being known as builts and the hollows as laagtes or vleys. The surface is occasionally broken by kopjes—either table-shaped or pointed—rising sometimes 100 ft. above the general level. Small springs of fresh water are frequent and there are several shallow lakes or pans—flat bottomed depressions with no outlet. The largest of these pans, Lake Chrissie, some 5 m. long by 1 m. broad, is in the south-eastern part of the high veld. The water in the pans is usually brackish. The middle veld is marked by long low stony ridges, known as rands, and these rands and the kopjes are often covered with scrub, while mimosa trees are found in the river valleys.

The banken veld, formed by the denudation of the plateau, is much broken up and is rich in romantic scenery. It covers about 27,000 sq. m., and has an average breadth of 40 m. In places, as between Mafeking and Johannesburg, the descent is in terrace-like steps, each step marked by a line of hills; in other places there is a gradual slope and elsewhere the descent is abrupt, with outlying hills and deep well-wooded valleys. The rocks at the base of the slopes are granite, the upper escarpments are of sedimentary rocks. Thence issue many streams which in their way to the ocean have forced their way through the ranges of hills which mark the steps in the plateau, forming the narrow passes or poorts characteristic of South African scenery.

As in the middle veld, rands and kopjes occur in the low or bush veld, but the general characteristic of this part of the country, which covers over 50,000 sq. m., is its uniformity. The low veld east of the Drakensberg begins at about 3000 ft. above the sea and slopes to 1000 ft. or less until it meets the ridge of the Lebombo hills. The lowest point is at Komati Poort, a gorge through the Lebombo hills only 476 ft. above the sea. West and north of the Drakensberg the general level of the low veld is not much below that of the lowest altitudes of the middle veld, though the climatic conditions greatly differ. North of the Zoutpansberg the ground falls rapidly, however, to the Limpopo flats which are little over 1200 ft. above the sea. Near the north-west foot of the Zoutpansberg is the large saltpan from which the mountains get their name. The low veld is everywhere covered with scrub, and water is scarce, the rivers being often dry in the winter season.

River Systems.—There are four separate river basins in the Transvaal. Of these the (q.v.) and its affluents, and the Pongola and its affluents rise in the high veld and flowing eastward to the Indian Ocean drain but a comparatively small area of the province, of which the Pongola forms for some distance the south-eastern frontier. The rest of the country is divided between the drainage areas of the Vaal and Limpopo. The (q.v.) rises in the high veld in the Ermelo district not far from the source of the Komati and that of the Usuto tributary of the Pongola. The Vaal drains the greater part of the plateau, flowing westward towards the Atlantic. The waters of the northern escarpments of the plateau and of all the region farther north are carried to the Indian Ocean by the (q.v.) and its tributaries the Olifants, Great Marico, Great Letaba, &c. Both the Vaal and the Limpopo in their main course have high steep banks. They carry an immense volume of water during the summer rains, but are very small streams in the winter, when several of their tributaries are completely dry. None of the rivers is navigable within the limits of the province. The absence of alluvial deposits of any size is another characteristic of the Transvaal rivers. For a considerable distance the Vaal forms the frontier between the province and the Orange Free State and in similar manner the Limpopo separates the Transvaal from Bechuanaland and Rhodesia. Since the first advent of white colonists many springs and pans and small streams have dried up, this desiccation being attributed, not so much to decreased rainfall, as to the burning off of the grass every winter, so that the water, instead of soaking in, runs off the hard, baked ground into the larger rivers.

Geology.

A broad ring of crystalline rocks (Swaziland schists) encircles the Transvaal except on the south, where the Karroo formation extends over the Vaal River. Within this nearly complete circle of crystalline rocks several geological formations have been determined, of which the age cannot be more definitely fixed than that they are vastly older than the Karroo formation and newer than the Swaziland schists.

The following subdivisions have been recognized by Molengraaff: Karroo System, Transvaal System, Vaal River System, South African Primary System. Each of these systems is separated from the other by a strong unconformity.

South African Primary System.—The South African Primary System includes a complex of rocks as yet little understood. According to Molengraaff it includes the two following series:—

Barberton Series.—Molengraaff considers the Barberton series to be the metamorphosed equivalent of the Hospital Hill series, while Hatch regards it to be older and to form a portion of his Archaean series (Swaziland schists) to which position it is here assigned. The chief outcrops are in the south-western Transvaal, around Zoutpansberg and in Swaziland. They show a great variety of type made up of slates, quartzites, occasional conglomerates, schists with large masses of intrusive granites and gneiss.

Witwatersrand Series.—It is now generally acknowledged that this important series consists of two main groups. Their chief occurrences are in the districts of Witwatersrand, Heidelberg, Klerksdorp and Venterskroon. The lower group (Hospital Hill slates) consists of quartzites and shales, resting on the eroded surface of the older granites and schists, and estimated to be from 10,000 to 12,000 ft. thick. There are occasional bands of conglomerates, sometimes auriferous. In the absence of fossils their age cannot be determined. The upper group consists of conglomerates, grits and quartzites with a few bands of shales. It has obtained notoriety from the conglomerates along certain bands containing gold, when they constitute the famous “banket.” The thickness varies from 2300 to over 11,000 ft. The conglomerate beds occur in belts forming in descending order the Elsburg series, Kimberley series, Bird Reef series, Livingstone Reef series, Main Reef series. The richest in gold are to be found among the Main Reef series, which yields by far the greater part of the total output of gold from the Transvaal. The individual beds, seldom more than a few feet in thickness and sometimes only a few inches, are interstratified with an immense thickness of quartzites. The conglomerates consist almost entirely of pebbles of quartz set in a hard