294 miss c. a. eaisin on [May 1903, 



where the rocks were ' much tilted ' and re- appeared ' again and 

 again 7 on the journey. One of these, pale yellowish-grey with 

 silvery surfaces, consists of lenticles of quartz-felspar mosaic, with 

 white and pale brown mica along streaks or zigzag lines. In a 

 much-crushed rock, from the same locality, the mosaic forming 

 pinkish streaks contains coarse patches with mica- or chlorite-nakes, 

 and crystals of felspar (orthoclase and plagioclase) much corroded. 

 In another granitic rock the narrow red felspathic bands (bouuded by 

 lines of biotite) consist of a mosaic, either fine-grained, containing 

 iron-oxide and some biotite, or coarse-grained with microcline, 

 white mica, and a streak of a secondary mineral, possibly a zeolite. 

 The rock probably owes its structure to fluxion-movements, and 

 resembles marginal specimens from a Yosges granite, the structure 

 of which I incline to attribute to this cause. (A gneiss from 

 Gumbi, towards the Nile Valley, weathering red, has a granular 

 matrix with streaky biotite and may be similar.) Another rock 

 from near Jibuli, from the river-bed, is reddish, banded, compact 

 and halleflintoid, not unlike a rhyolite ; but the constituent 

 grains of the mosaic are often angular and clearly defined, so 

 that (like some of the preceding specimens) it is probably a crushed 

 and recrystallized gneiss, somewhat similar to certain Saxon 

 granulites. 



A pale-grey, medium-grained, noncrystalline rock, from the top of 

 a steep hill on the road from Mendi to Gumbi (Gimbi), is composed 

 of plagioclase-felspar and quartz, with ragged flakes of biotite, clear 

 epidote. and some sphene. 



(3) Hornblende-Schists and Foliated Diorites 



are all blackish fine-grained rocks, containing plagioclase, biotite, 

 hornblende, iron-oxide, with sometimes augite, and occasionally a 

 zircon. One specimen, from north-west of Quattie Camp towards 

 the Blue Nile Valley, is ophitic ; but the structure in the rocks 

 generally is granular and often fluxional, as in one south-west of 

 Berbera, and in one towards Fyambiro, while two others exhibit a 

 slightly-brecciated appearance. A schist from between the Dabus 

 River and Jem Jem is undoubtedly crushed, traversed by narrow 

 prisms of hornblende with a parallel arrangement. In another 

 schistose rock from Gumbi (one specimen of it coming from the summit 

 of the hill) bright brick-red and brown patches are present. These 

 are rich in narrow prisms of (possibly) an iron-stained epidote, while 

 the wavy bands of mosaic in the slice contain some iron-oxide. 

 Small micaceous or kaolinized aggregates have been formed probably 

 from felspar-crystals. The rock may be a much-crushed ferriferous 

 diorite. 



(4) Diabase ; Hornblendic Gabbro ; Pyroxenite. 



These rocks all come from the South-west of Abyssinia, from 

 localities where some granitic or dioritic rocks occur. A specimen 

 from Gumbi exhibits green hornblende with patches of epidote and 



