134 Reports and Proceedings. 



action in Western India. They probably belong, in his opinion, to 

 two periods, as dykes of different grain frequently intersect each 

 other. The dykes running N.E. and S.W. often traverse and slightly 

 dislocated those lying more N. and S., and are probably of later date. 

 Discussion. — Mr. David Forbes did not see any proof of the dykes being of 

 different ages. In modern eruptions, lasting over some years, the lava iirst erupted 

 sometimes became fissui-ed, and the fissures filled at a later period of the eruption. 



4. " On Auriferous Eocks in South-eastern Africa." By Dr. 

 Sutherland. Communicated by Sir E,. I. Murchison, Bart., F.E.S., etc. 



Fourteen years ago the author expressed the opinion that gold 

 would be found in the metamorphic rocks of Natal. A few months 

 since Mr. Parsons found this metal by washing the iron sand of 

 some of the southern rivers of the colony. The gold is in micro- 

 scopic rounded grains. Dr. Sutherland considers that the gold is 

 diffused as minute particles in the granite and gneiss underlying the 

 Silurian rocks of South Africa. 



These old gneissic rocks are very much contorted, include ex- 

 tensive veins and lenticular masses of quartz, and are traversed by 

 basalts. The Silurian strata, resting unconformably on the gneiss, 

 have been invaded by igneous matter (which is never granitic), and 

 thongh generally horizontal, are frequently flexuous, and in some 

 places greatly faulted, to the extent of even 1000 feet, together 

 with the gneissic rocks beneath. These latter have been deeply 

 eroded by the rivers, frequently to the depth of 500-1000 feet, and 

 even of 3000 feet in some valleys ; and in the alluvia of these 

 valleys the gold occurs. The valleys have sometimes evidently 

 commenced in great displacements, forming "valleys of elevation," 

 on which the denuding agency has been operating ever since. 



In certain mountains in the basin of the St. John's Eiver, Natal, 

 dioritic rock traverses the secondary strata ; and along the line of 

 contact it contains copper-ores with 100 grains of gold to the ton. 



II.— February 10th, 1869.— 1. " On the Evidence of a ridge of 

 Lower Carboniferous Eocks crossing the Plain of Cheshire beneath 

 the Trias, and forming the boundary between the Permian Eocks of 

 the Lancashire type on the North and those of the Salopian type on 

 the South." By Edward Hull, Esq., M.A., F.E.S., F.G.S. 



In this paper the author proposed to account for the dissimilarity 

 of mineral and stratigraphical characters of the Permian formation 

 of Lancashire and the North of England as compared with that of 

 the Midland Counties and Shropshire, on the ground that they had 

 originally been deposited in separate basins, divided off from each 

 other by a ridge of Lower Carboniferous rocks, stretching from 

 west to east, under the central plain of Cheshire. 



The author showed that there was evidence of such a ridge on the 

 east side of the plain of Cheshire, by the uprise of the Lower Car- 

 boniferous rocks to the north of Cbngleton edge, in the valley of the 

 Eiver Dane, and that the date of this uprise and the denudation of 

 the Upper Carboniferous beds along the axis of elevation was clearly 

 determined to be antecedent to the Permian period by the outlier of 

 Permian rocks at Eushton Spencer. 



