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.