eed. 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.

This Chicova is not a kingdom, as has been stated, but a level tract, a
part of which is annually overflowed by the Zambesi, and is well adapted
for the cultivation of corn. It is said to be below the northern end
of the hill Bungwe. I was very much pleased in discovering this small
specimen of such a precious mineral as coal. I saw no indicat