The similarity of conformation and nature of the rocks
on both sides of the continent; but there is a difference
in the structure of the subtending ridges, as may be understood
by the annexed ideal geological section.
==
[The ASCII edition cannot include the drawing of the cross-section,
but the comments are included in full. - A. L., 1997.]
IDEAL SECTION ACROSS SOUTH CENTRAL AFRICA,
INTENDED TO SHOW THE ELEVATED VALLEY FORM OF THAT PORTION OF THE CONTINENT.
- - - - - - - - - - - - - - - - - - -
WEST.
[Terrain] [Remarks]
Sea. CALCAREOUS TUFA.
TRAP. With modern shells, and similar to those now found
in the sea adjacent, with strongly magnetic iron ore.
MICA SCHIST. Dipping East.
SANDSTONE (like that of East Africa). The rocks
Pungo Andongo. of Pungo Andongo are a conglomerate of rounded shingle in
Rocks 4000 feet. a matrix of sandstone, and stand on horizontal sandstone,
on which fossil palms appear.
Fault.
RED SHALES CAPPED BY FERRUGINOUS CONGLOMERATE.
Soft red shale or "keele".
G| 5000 feet.
R| Water boils
E| at 202 Deg.
A| On top, ferruginous conglomerate; below that, red shale,
T| 4500 feet. with banks of gravel.
| Lake Dilolo.
C| TUFA AND TRAP. In Londa, the bottom of the valley
E| 2500 feet. is formed of ferruginous conglomerate on the surface;
N| Lake Ngami. hardened sandstone, with madrepore holes,
T| banks of gravel, and occasionally trap;
R| south of 12 Degrees, large patches of soft
A| TUFA.
