290 AUEIFEKOTJS COifaLOMEKATES OE THE GOLD COAST. [Aug. 189B, 



23. On the ORiaiis- of the Aurifeeous Coij^tglomeeates of the Gold 

 Coast Colony (West Afeica). By T. B.P.Sam, Esq., C.E. (Com- 

 municated by J. L. Loblet, Esq., F.G.S. Read April 20th, 1898.) 



[Abstract.] 



This paper gives an account of a recent journey^ from Adjah Bippo 

 to the Ankobra Junction in the Gold Coast Colony. A range of 

 clay-slate hills is succeeded for 6 miles by flat ground in which 

 diorite -was found, and that by a lofty hill in which clay-slate 

 dipping east occurs. The Teberibie range with reefs of con- 

 glomerate, and a second range with similar reefs, were crossed. 



Gold-bearing alluvia are briefly described, and the gold is 

 supposed to have come from the hills. The Adjah Bippo, Tarkwa, 

 and Teberibie formations are considered to be part of a syncline. 

 Certain auriferous conglomerates, and others presumed to be 

 identical with them, are thought to be ancient alluvial deposits. 



Discussion. 



Mr. F. Steuben said that he had carefully examined the auriferous 

 conglomerates stated by the Author to exist on the Gold Coast, and 

 as he (the speaker) had had considerable practical experience of 

 conglomerates, having discovered those of Johannesburg in South 

 Africa, he had no hesitation in stating that those of West Africa 

 were identical in their character and age with those of Johannes- 

 burg. He did not agree with the Author in thinking that the 

 West African conglomerates were derived from the disintegration 

 of the existing range of mountains which rises a little farther 

 inland, but he thought that they undoubtedly belonged to a far earlier 

 period, and were similar in age to those of South Africa. They were 

 evidently part of the series of sedimentary deposits which so largely 

 predominate over the surface of the African continent. He thought 

 that in these conglomerate-beds of West Africa there would be found 

 deposits as extensive and as rich in gold as those of South Africa. 



Mr. J. C. Wylie said that, from personal knowledge and actual 

 work on the conglomerate-reefs of Johannesburg and the Tarkwa 

 district of the Gold Coast, he fully endorsed the previous 

 speaker's remarks as to their identical character. Further, that in 

 many cases a main reef of poor quality ran parallel to a narrow 

 leader of rich quality, in the manner so well known around 

 Johannesburg ; and that in both countries the gold was principally 

 in the cement, and not in the pebbles of the conglomerates. It 

 gave him pleasure to hear such a paper from a native gentleman of 

 the Gold Coast, as it showed considerable j)owers of observation. 



Mr. Teall asked what evidence there was in the paper "of the 

 auriferous character of the conglomerates. 



Mr. Lobley regarded the auriferous conglomerates of Adjah 

 Bippo as so like those of the Transvaal as to be identical, and held 

 therefore that this paper had an important geological value. The a«"e 

 of these conglomerates, from the South African geological structure 

 he regarded as Palaeozoic. 



