146 de. f. Oswald on the [June 1 9 14, 



Along a zone about 50 feet above the present level of the Kuja 

 Valley (that is, at an altitude of about 4000 feet), occur quantities 

 of well-rounded pebbles of quartzite (measuring up to 6 inches 

 in length), which have evidently been brought down hj the Kuja 

 from the parent-rock of the quartzite of the Kisii Highlands at a 

 time when the river flowed at a higher level than at the present 

 day. This zone of quartzite-pebbles is well marked along both 

 sides of the Olasi Valley, especially on its south side, between 

 Nangina and Nyaroya, and also along the low ridge above the 

 Ogo Ford north of Yangena. 



Although further evidence is necessary, it seems to me probable 

 that this zone of pebbles at the 4000-foot level marks an old 

 beach-line of the Victoria Nyanza. It is extremely noticeable, both 

 in this district and in the area south of the basaltic cliffs of Nira, 

 Kachuku, and Kikongo, that all the hills and contours below 

 this altitude are gentle and rounded (for instance, Rabur), with 

 particularly broad valleys ; while abruptly above this level I noticed 

 pointed hills (for instance, Mirema), terminating in rough and 

 rugged crags. Exactly the same striking contrast is noticeable in 

 looking across the Kavirondo Gulf from Kendu, vividly recalling 

 the contrast in Norway between the lower rounded glaciated slopes 

 and the non-glaciated crags and peaks above them. This level is 

 roughly about 300 feet above the present level of the lake, which 

 must (at this altitude of 4000 feet) have just reached to the foot 

 of the basaltic cliffs, and must have chiefly contributed to the 

 destruction of the Miocene deposits at their base. On the western 

 shore of the Victoria Nyanza, gravel-deposits and caves occur at a 

 height exceeding 300 feet above the lake in the cliffs of the coast 

 of Buddu, north of the Kagera River. 1 



In proceeding eastwards from Metamala I found that the coarse 

 agglomerate persists up to the gneiss of Gongogongo, without 

 passing into tuff as it does on the west and south. The acacia 

 forest on the steep slopes of this range of hills precluded any exact 

 observations of the mutual relations of these rocks, but the gneiss 

 forms a gigantic obelisk of colossal, bare, rounded blocks, thus 

 constituting a natural landmark for many miles round. The rock 

 is a pink granitic biotite-gneiss, 2 weathering pale brown, and 

 probably was originally an intrusive granite. On the north-east side 



1 Sir William Garstin, 'Eeport on the Upper Nile ' Cairo, 1904, pp. 32-39. 



2 This rock contains numerous allotriomorphs (measuring up to 9 mm. in 

 longest diameter) of orthoclase (microperthite), of tabular habit with 

 Carlsbad twins, and traversed by a finely dusty perthitic network ; sometimes 

 displaying a brecciated margin of plagioclase. Plagioclase (oligoclase- 

 andesine, AboAni) is subordinate, occurring in smaller crystals (measuring 

 up to 7 mm. in longest diameter), often interstitial between the larger ortho- 

 clase-crystals ; occasionally turbid centrally with flakelets of white mica, but 

 clear marginally. Biotite (up to 2 mm.) is only sparingly present, some- 

 times with bent lamellae ; it encloses zircons with pleochroic halos, as well as 

 magnetite and apatite. Magnetite is accessory, enclosing apatite. Quartz 

 occurs in large interstitial grains, containing strings of very small fluid inclu- 

 sions, and sometimes displays brecciated margins ; it encloses biotite, and 

 occasionally plagioclase. 



