GEOLOGICAL FORMATION OF ANGOLA. 447 
up schist, gneiss, &c. ; while, in the latter, 
veins, or rather cracks, may be seen, filled with 
a dark bine rock, exactly like clay slate. In 
the districts of Cazengo and Golnngo Alto, 
abundance of excellent iron ore occurs, some 
strongly magnetic, other parts not, but all very 
largely impregnated with the metal. To the 
North, near the river Daude, petroleum is re- 
ported ; and so it is said to occur likewise to- 
wards the South, under the dark red sandstone 
which forms the crust of the country. The 
spot reported is on the banks of the Coanza, 
and near Cambambe. Yeins of copper appear 
also on the banks of this river, in the same dis- 
trict, but I did not see them. The rocks of 
Pungo Andongo are composed of large masses 
of conglomerate, rising about 300 or 400 feet 
above the surrounding country. They stand 
in parallel lines, nearly North and South in di- 
rection, and rather more than a mile in length. 
The conglomerate stands on horizontal strata of 
dark red sandstone, and this in a very small 
proportion to the other materials, form the 
matrix. There are granite, gneiss, porphyry, 
schist, clay, and sandstone, trap, syenite, green- 
stone, quartzite, &c, all round and water-worn, 
and forming immense masses of shingle. There 
is also a soft limestone, containing shells, found 
lying on the tops of some of the rocks. 
