﻿Vol. 6 1.] NORTH-EASTERN TERRITORIES OF THE CONGO FREE STATE. 651 



Farther north, near Vankerckhovenville, 1 and on the Uelle-Kibali, 

 Mounts Gaima and Yagu present some points of interest in their 

 great analogy of structure with Mount Tena, iron-ore beds being 

 also much in evidence. (See fig. 1, p. 652.) 



Mount Gaima (3960 feet above sea-level) is situated about 

 8 miles west of Yankerckhovenville, and is quite close to the Uelle- 

 Kibali River. Similarly to Mount Tena, it presents in its upper 

 part great beds of iron-ore striking north-west and south-east, but 

 here the dip is easterly at an angle of 54°. These ferruginous beds 

 appear to be underlain on the west side by a diabasic rock, and 

 are probably interstratified with it. At the base of the hill, near 

 the river, and on the east side, the ground is thickly covered by a 

 bed of pebbles, of the same nature as the iron-ore met with on the 

 top ; but no conglomerate is to be seen, and the pebbles are not 

 cemented together. 



The iron-ore of Mount Gaima is a haematite of very dense 

 character. The beds are magnetic on the summit. 



Mount Yagu (4400 feet above sea-level) is a few miles farther 

 to the south, and has also a stratum of iron-ore near its summit. 

 The strike here is east and west, and the dip northerly. The 

 difference of strike and dip from those observed on Mount Gaima 

 points to local displacement of the beds. The thickness of the 

 iron-ore formation here was estimated at 200 or 300 feet ; it was 

 observed on the northern face, where the rocks form a precipitous 

 cliff. 



The natives of that part procure their iron for making knives, 

 spears, etc. from this mountain, at a spot where the ore is 

 much softer than elsewhere, and brittle. In their primitive 

 attempts at mining they have dotted the hill-slopes round about 

 with many shallow pits, the biggest being hardly wide enough for 

 a man to crawl into. 



From Yankerckhovenville to Dungu a kind of phyllite covers 

 a fairly-wide extent of country, being first seen at Dungu, and then 

 at the Rapids of Makassa and in places as far as the River Obu. 



In the neighbourhood of Yankerckhovenville itself outcrops of 

 diabase were met with. 



Vankerckhovenville — Farach. 



In travelling in a north-easterly direction, towards Farach, a 

 small outcrop of gneiss was met with between the Uelle-Kibali 

 and the Nzoro Rivers, striking north and south, and dipping about 

 11° eastward. Farther on, a small hill, situated about 10 miles 

 north-east of Yankerckhovenville, forms an outcrop of diabasic 

 rock. Thence onward to Farach the country becomes almost 

 level, and offers to view only some granitic rocks, specimens of 

 which were obtained at the Rivers Kwado and Aro respectively, 

 and also between the Nzoro and the Uelle-Kibali Rivers. 



1 VKH on the map (PI. XLII), just across the Nzoro River from Mount 

 Gaima. 



