GEOLOGICAL STRUCTURE. 491 



E.) on the 7th May. This is a stream of thirty yards wide, and, 

 like the Quilo, Loange, Chikapa, and Loajima, contains both alli- 

 gators and hippopotami. We crossed it "by means of canoes. 

 Here, as on the slopes down to the Quilo and Chikapa, we had an 

 opportunity of viewing the geological structure of the country — 

 a capping of ferruginous conglomerate, which in many parts looks 

 as if it had been melted, for the rounded nodules resemble masses 

 of slag, and they have a smooth scale on the surface ; but in all 

 probability it is an aqueous deposit, for it contains water-worn 

 pebbles of all sorts, and generally small. Below this mass lies a 

 pale red hardened sandstone, and beneath that a trap-like whin- 

 stone. Lowest of all lies a coarse-grained sandstone containing a 

 few pebbles, and, in connection with it, a white calcareous rock is 

 occasionally met with, and so are banks of loose round quartz peb- 

 bles. The slopes are longer from the level country above the fur- 

 ther we go eastward, and every where we meet with circumscribed 

 bogs on them, surrounded by clumps of straight, lofty evergreen 

 trees, which look extremely graceful on a ground of yellowish 

 grass. Several of these bogs pour forth a solution of iron, which 

 exhibits on its surface the prismatic colors. The level plateaus 

 between the rivers, both east and west of the Moamba, across 

 which we traveled, were less woody than the river glens. The 

 trees on them are scraggy and wide apart. There are also large 

 open grass-covered spaces, with scarcely even a bush. On these 

 rather dreary intervals between the rivers it was impossible not 

 to be painfully struck with the absence of all animal life. Not a 

 bird was to be seen, except occasionally a tomtit, some of the 

 Sylviadce and Drymoica, also a black bird (Dicrurus Ludivigii, 

 Smith) common throughout the country. We were gladdened 

 by the voice of birds only near the rivers, and there they are 

 neither numerous nor varied. The Senegal longclaw, however, 

 maintains its place, and is the largest bird seen. We saw a 

 butcher-bird in a trap as we passed. There are remarkably few 

 small animals, they having been hunted almost to extermination, 

 and few insects except ants, which abound in considerable number 

 and variety. There are scarcely any common flies to be seen, nor 

 are we ever troubled by musquitoes. 



The air is still, hot, and oppressive ; the intensely bright sun- 

 light glances peacefully on the evergreen forest leaves, and all 



