382 Reports & Proceedings — Geological Society of London. 



is a varying thickness of (usually unstratified) clayey sands, probably 

 late Pliocene — the Benin Sands Series of Mr. J". Parkinson. 



Along the coast-line and extending for considerable distances up 

 the Niger and Cross Ptivers are fluviatile, deltaic, littoral, and swamp 

 gravels, sands, and muds of Pleistocene and recent age. In the 

 Cross-River basin, intruded into the marine Cretaceous, are volcanic 

 necks of decomposed agglomerate, and sills (?) and dykes of olivine- 

 dolerite. These are probably Pre-Eocene. 



Faulting and local folding are visible in various portions of this 

 district. Numerous silver-lead-zinc- iron lodes occur along these 

 fault-lines, with brine-springs in several localities. 



The Yorubaland crystalline rocks contain magnetite in considerable 

 quantities, while these and the crystalline rocks of the Oban Hills 

 show smaller quantities of cassiterite, gold, monazite, and columbite. 



2. " I^otes on the Extraneous Minerals in the Coral Limestones of 

 Barbados." Bv John Burchmore Harrison, C.M.G., M.A., F.G.S., 

 F.I. C., and C. B. W. Anderson. 



Characteristic representative specimens of the fossil reef-corals 

 and of the beach-rock of the high-level and low-level limestone 

 terraces of Barbados were examined chemically and microscopically, 

 in order to ascertain the composition, nature, and origin of their 

 extraneous mineral contents. A special method was used, whereby 

 the extraneous mineral matters were separated, practically without 

 alteration, from large quantities of the limestones. Chemical 

 analyses of the residua were made, and the results of these and of 

 the microscopical examinations are tabulated in the paper. The 

 extraneous minerals present were found to be apparently fresh and 

 largely unaltered fragments of wind-borne volcanic minerals and 

 glass. It was found that the volcanic minerals enclosed in the reef- 

 corals on which they fell have been protected from change; those in 

 the clastic limestone or bed-rock show signs of detrition and 

 weathering prior to the consolidation of the limestone. Similar 

 minerals separated from clay normally formed and accumulated in 

 a pothole in the limestone supply evidence of weathering changes 

 after being set free from the rock. It is shown that the composition 

 of the sedentary residual soils on the higher limestone terraces of 

 Barbados corresponds in its essential parts with the residua separated, 

 either naturally or artificially, from the limestone. 



The proportions of magnesium carbonate present in the coral-rock 

 are briefly discussed, and complete analyses of the high-level and the 

 low-level limestones are given. A note on the proportions of 

 titanium oxide in the Barbados Oceanic clays and in some of the 

 Challenger and Buccaneer deep-sea dredgings is appended to the 

 paper. 



IT. MlNEKALOGICAL SOCIETY. 



June 17, 1919.— Dr. A. E. H. Tutton, F.R.S., Past-President, in the 



Chair. 



A. E. Kitson : " Diamonds from the Gold Coast." The crystals 

 and their occurrence were described. 



