268 
GEOLOGICAL FOEMATION. 
May \0th . — We went on shore to take angles for the 
survey of the channel, and a set of niagnetical observa- 
tions*. The latter were made on the cliff near Lilly’s 
palm-tree ; but the operations were interrupted by a 
tornado. 
* The geological character of each bank of the Cameroons river — 
more properly the Madiba ma Dualla— is quite distinct. While the 
right is uniformly low swampy land for several miles towards the 
base of the mountain, covered in most parts with mangroves, and in- 
tersected by numerous creeks^, the left bank rises at once from the 
waterside to the lieight of about fifty feet. It is conglomerate of 
recent age, containing particles of quartz, about the size of a walnut; 
small fragments of whitish mica, and of masses of red sandstone, some 
of which measured four feet ; the whole, held in combination, by a 
light brown clay. The stratification is horizontal, the thickness of 
the beds varying from a few inches to several feet, in which I could 
not detect any fossil remains. 
These fragments of sandstone are composed of particles of quartz 
held together by oxide of iron. The iron ore is also found in small 
fissures of the mass, which are about 0*5 of an inch in thickness, 
intersecting it in every direction. It is not uncommon to see the iron 
ore chemically combined with clay, in compact masses of the size of 
several square inches. 
The influence of this abundance of iron ore on the magnetic needle 
would be greatest at the base of the cliff ; yet it was found to be so 
strong on the surface, as to produce different results in observations 
made only a few yards apart.— M. Roscher’s Geological M,S, 
1 The opposite bank has a ledge of rocks visible only at low water, 
corresponding in appearance with the compact masses of sandstone at 
the base of the cliff on the left bank. This may lead to the supposi- 
tion that the real or diJuvial right bank has formerly reached equally 
far as its opposite, but has been submerged by some convulsion of its 
anciently unquiet neighbour, the mountain. The river seems now in 
process of reconstmcting its hank — so ruthlessly destroyed — by the 
formation of a delta. — W. A. 
