The course of the Nile being in the opposite direction to this, it does not receive these subsidiary waters, and hence its inundation is recognized all the way along its course.  If the Leeambye were prolonged southward into the Cape Colony, its flood would be identical with that of the Nile.  It would not be influenced by any streams in the Kalahari, for there, as in a corresponding part of the Nile, there would be no feeders.  It is to be remembered that the great ancient river which flowed to the lake at Boochap took this course exactly, and probably flowed thither until the fissure of the falls was made.

This flood having filled the river, we found the numerous rivulets which flow into it filled also, and when going along the Zambesi, we lost so much time in passing up each little stream till we could find a ford about waist deep, and then returning to the bank, that I resolved to leave the river altogether, and strike away to the southeast.  We accordingly struck off when opposite the hill Pinkwe, and came into a hard Mopane country.  In a hole of one of the mopane-trees I noticed that a squirrel (’Sciurus cepapi’) had placed a great number of fresh leaves over a store of seed.  It is not against the cold of winter that they thus lay up food, but it is a provision against the hot season, when the trees have generally no seed.  A great many silicified trees are met with lying on the ground all over this part of the country; some are broken off horizontally, and stand upright; others are lying prone, and broken across into a number of pieces.  One was 4 feet 8 inches in diameter, and the wood must have been soft like that of the baobab, for there were only six concentric rings to the inch.  As the semidiameter was only 28 inches, this large tree could have been but 168 years old.  I found also a piece of palm-tree transformed into oxide of iron, and the pores filled with pure silica.  These fossil trees lie upon soft gray sandstone containing banks of shingle, which forms the underlying rock of the country all the way from Zumbo to near Lupata.  It is met with at Litubaruba and in Angola, with similar banks of shingle imbedded exactly like those now seen on the sea-beach, but I never could find a shell.  There are many nodules and mounds of hardened clay upon it, which seem to have been deposited in eddies made round the roots of these ancient trees, for they appear of different colors in wavy and twisted lines.  Above this we have small quantities of calcareous marl.

As we were now in the district of Chicova, I examined the geological structure of the country with interest, because here, it has been stated, there once existed silver mines.  The general rock is the gray soft sandstone I have mentioned, but at the rivulet Bangue we come upon a dike of basalt six yards wide, running north and south.  When we cross this, we come upon several others, some of which run more to the eastward.  The sandstone is then found to have been disturbed, and at the rivulet called Nake we found it tilted up and exhibiting a section, which was coarse sandstone above, sandstone-flag, shale, and, lastly, a thin seam of coal.  The section was only shown for a short distance, and then became lost by a fault made by a dike of basalt, which ran to the E.N.E. in the direction of Chicova.