#50 Geological Society : — 



above sea-level, indicate aii important submergence and subsequent 

 elevation in comparatively-late times, while from the latter much 

 of the present physiography appears to date. The Benin Sands 

 have been seen in contact with both the older groups of sediments, 

 but unfortunately the work has not proceeded far enough yet to 

 show conclusively the relationships of the latter. 



The older of the two, the Lignite Series, occurs typically near 

 Asaba on the Niger, although indications of a similar deposit have 

 been met with near Moroko, south of Abeokuta ; the younger, the 

 Ijebu Series, has so far been found only in that district of the 

 Lagos Province. These beds are extensively impregnated with 

 bitumen. The suggested difference of age depends on the lesser 

 dip and degree of consolidation of the Ijebu Series. In them a 

 few lamellibranchs have been found, of no value as regards the 

 determination of the horizon, and some plant-remains; in the 

 Lignite Series only undeterminable plant-remains. The Benin 

 Sands are apparently unfossiliferous. The information regarding 

 the Ijebu Beds has been derived almost entirely from boreholes. 



2. ' The Geology of the Oban Hills (Southern Nigeria).' By 

 John Parkinson, B.A., P.G.S. 



The country described in this paper comprises some 1800 square 

 miles of the Eastern Province of Southern Nigeria, adjacent to the 

 Kameruns frontier. The rocks are crystalline, principally gneisses 

 and schists with later granites, pegmatites, and basaltic dykes, 

 surrounded on the north, west, and south by Cretaceous sediments. 

 For purposes of description the series is divided under nine headings, 

 according to locality and petrographical character ; and it is con- 

 cluded that, neglecting the basaltic dj-kes, two broad groups may 

 be distinguished — the one characterized by the presence, the other 

 by the absence, of foliation. In the former the foliation tends to be 

 lost, giving a passage between types which petrographically are 

 acid orthogneisses and granites. 



Observation of the banded gneisses, which are typical of several 

 districts, leads to the conclusion that the acid magma is intrusive 

 into mica and hornblende-schists, and that the banded gneisses are 

 composite rocks produced by injection. The orthogneisses them- 

 selves exhibit many variations ; and study in the field shows that 

 the series consists of several members, produced by the differen- 

 tiation probably of one magma, which have reached their present 

 positions at different times : that is, they differ slightly in age. At 

 Uwet was found a group of phyllites and grits altered into garnet, 

 andalusite, and staurolite-schists, and hornfels, with the develop- 

 ment of much biotite, by an intrusive gneiss ; and it is considered 

 as probable, though not capable at the time of absolute proof, that 

 the sillimanite-gneisses of the Ekankpa ford, a few miles away, are 

 the result of an extension of the same belt of contact-metamorphism, 

 a suggestion which possibly might truly include the schists of the 

 entire district. 



Typical specimens of the granites, pegmatites, and dykes are 

 described, and sketch-maps given. 



