﻿646 MK. G. E. J. PREUMONT ON THE GEOLOGY OE THE [Aug. T905, 



The Iron-Mountains of the Uelle. 



Amadi — Poko. 



At a distance of about 15 miles from Amadi we came across an 

 important group of hills, the principal being Mount Angba, situated 

 on the right bank of the (Telle. North of Mount Angba is Mount 

 Lingwa ; southward, but across the Uelle, are seen Mount Mandjana 

 and other minor hills. 



The altitude of Mount Angba (by hypsometric observation) is 

 about 2867 feet above sea-level, the summit being nearly 650 feet 

 above the level of the river. The eastern face is, in its upper 

 portion, rather abrupt. On the south and south-west, the slope is 

 also very steep. North-westward, the ground falls away more 

 gradually, and northward extends towards Mount Lingwa in the 

 shape of a long ridge. 



The mountain is an enormous mass of iron-ore, stretching for a 

 couple of miles in length in a north-and-south direction, by about 

 half a mile in width. Near the top immense beds of haematite are 

 laid bare, in a series of layers resting on edge, and several hundred 

 feet thick. The strike is N. magn. to 20° W., and the dip 60° to 70° 

 westward. The rocks on the top appeared to affect the compass. 



This group of hills, comprising Mounts Angba, Lingwa, Mandjana, 

 and others, has somewhat the shape of a range, not well-defined, 

 but extending apparently in a southerly direction towards Poko. 

 Hills of similar nature situated between the Uelle and the Bomo- 

 kandi lead us to suppose that the range may be continuous as far as 

 Poko, where Mount Madjema, another iron- ore mountain, is also to 

 be seen. The iron-ore met with in this group is mostly a massive 

 black haematite, and appears to be very similar to the iron-ore found 

 on Mounts Gaima and Tena (see pp. 648, 651). 



Eastward of Mount Angba, a few miles farther on, granite 

 reappears at a rapid on the river, and so it seems probable that the 

 iron-ore beds of Mount Angba are interstratified with the crystalline 

 series, but no direct evidence of this could be gathered. By the 

 overland route, passing a few miles north of the mountain, on the 

 ridge that extends towards Mount Lingwa, the only rocks observable 

 are layers of haematite and large stretches of limonitic puddingstone. 



Niangara — Ndoruma. 



Past Suronga, which has an altitude of about 3260 feet, and 

 towards Niangara, the rocks are of metamorphic type. The rapid 

 called Naka is formed by a band of quartzite, striking north and 

 south, with a slight westerly dip. At a stream called Kit a li, not 

 very far west from Niangara, we noticed mica-schist also trending 

 north and south. At Niangara the altitude of the Uelle River is 

 2230 feet. 



North of Niangara is a very flat country, devoid of hills and 



