At which the walls are so sloping
that people accustomed to it can go down by descending in a sitting position.
The Makololo on one occasion, pursuing some fugitive Batoka,
saw them, unable to stop the impetus of their flight at the edge,
literally dashed to pieces at the bottom. They beheld the stream
like a "white cord" at the bottom, and so far down (probably 300 feet)
that they became giddy, and were fain to go away holding on to the ground.
Now, though the edge of the rock over which the river falls does not show
wearing more than three feet, and there is no appearance of the opposite wall
being worn out at the bottom in the parts exposed to view,
yet it is probable that, where it has flowed beyond the walls,
the sides of the fissure may have given way, and the parts out of sight
may be broader than the "white cord" on the surface. There may even be
some ramifications of the fissure, which take a portion of the stream
quite beneath the rocks; but this I did not learn.
If we take the want of much wear on the lip of hard basaltic rock
as of any value, the period when this rock was riven is not geologically
very remote. I regretted the want of proper means of measuring and marking
its width at the falls, in order that, at some future time,
the question whether it is progressive or not might be tested.
It seemed as if a palm-tree could be laid across it from the island.
And if it is progressive, as it would mark a great natural drainage
being effected, it might furnish a hope that Africa will one day become
a healthy continent.