Vol. 70.] MIOCENE OF THE YICTOBIA tfYANZA, ETC. 159 



o£ the other gneisses of which I collected specimens, and is probably 

 older in date, stretches far away to the east-north-east through 

 the districts of Nyakongo and Xyakaeh. South of this gneissic 

 area lie the slates of Wire Hill (a conspicuous flat-topped hill 

 rising to 5276 feet), but I "vyas unable to examine them. Their 

 distribution is approximately indicated in a sketch-map (which 

 Mr. C. W. Hobley kindly allowed me to examine) made by 

 Mr. J. S. Coates, G-oyernment G-eologist, in 1909. He designates 

 these slates the Wire Hill Beds, and they appear to be associated 

 in places with chalcopyrite in quartz and graphite, according to 

 information kindly given to me by Mr. Gr. E,. Chesnaye. Probably 

 they belong to the same series as the schists at the base of the 

 Vinyo Escarpment, but their relations to the gneiss are as yet 

 unknown. 



Appexdix I. 



Abridged Statement of the Downward Succession of the 

 Miocene Beds at Nira, with Indications of the Points of 

 Difference from the Outcrops at South Nira, West 

 Kachuku, Kachuku, East Kachuku, and Kikongo. 



Upper Series (Nos. 1-12). 

 Beds. Thickness in feet. 



No. 1. Grey clays with calcified tree-stems, overlying a greenish- 

 grey conglomerate, passing down gradually into argilla- 

 ceous sandstone 8 



No. 2. Pale greenish-grey clay, with seams of brown shales 8 



No. 3. Brown clay, with thin seams of shale ; northwards the 

 clay becomes grey. At East Kachuku and Kikongo 

 Nos. 2 & 3 consist of grey current-bedded sandstones, 

 containing biotite and augite 9 



No. 4. Pale-grey clay. At East Kachuku it becomes an argilla- 

 ceous sandstone 8 



No. 5. Hard grey clay, passing (at South Nira) into sandstone 

 containing biotite and augite. At Kachuku it contains 

 Ampullaria ovata and crocodiles' teeth 2^ 



No. 6. Soft grey clay 2| 



No. 7. Pale-brown clay with septarian nodules ; eastwards it be- 

 comes shaly 3 



No. 8. Grey calcareous sandstone, with thin seams of grey clay. 

 At Kikongo it is current-bedded, containing augite and 

 enclosing a few land-shells (Tropidopliora nyasana, Limi- 

 colaria, and Cerastus) 6 



No. 9. Thinly -bedded grey clays and brown shales. At Kachuku 

 and Kikongo the clay alternates with thin seams of 

 travertine, and at Kikongo the lower part contains seams 

 of grey sandstone 7 



No. 10. Brown clay. At Kachuku and Kikongo it consists of grey 



clay, with thin seams of travertine 5 



No. 11. Grey clay. At South Nira the upper foot is a massive grey 



sandstone 5 



No. 12. Brownish-grey clay yielding a river-crab (Tefyphu&a) and 

 scutes of crocodile. At South Nira and Kachuku are 

 numerous seams of shale. At Kikongo the lower half 

 consists of grey sandstone 4^ 



