84 Notices of Memoirs— E. II. L, Sehirarz — Bariaan's Kloof. 



is occasionally greenish in colour. Locally there occur in the 

 conglomerato lenticular patches of iine-grained, massive, white or 

 cream-coloured sandstones, and white, finely laminated shales and 

 mudstones. 



Tlie progressive denudation of the glacial conglomerate exposes 

 at its margin the glaciated surfaces of the underlying rocks, which 

 frecpiently show very clear striation. The best examples yet met 

 witli are those occurring to the north of the Douglas Colliery near 

 Balmoral. In a number of examples distributed over an area of 

 300 square miles the stritu exhibit great constancy of direction, and 

 point to the existence of an extensive ice-sheet with a movement 

 from N.N.W. to S.S.E. 



It is very probable that the glacial conglomerate extends very 

 much further north than the localities at present known. During 

 the past year outliers of the conglomerate were found ninety miles 

 north of the latitude of Johannesburo-. 



V. — The Plutonio Rooks and their Relations with thr 



OllYSTALLINK SoiIISTS AND OTIIKK FORMATIONS. By F. . P. 



Mknnkll. 



IT has been pointed out by Teall that the linal solution of the 

 problems arising in connection with the origin of igneous 

 magmas is possibly to be looked for where the plutonio rocks are 

 seen in their relations with the crystalline schists. The writer 

 dealt with observations made in such an area and the inferences to 

 be drawn therefrom. He concluded that the average igneous rook 

 has practically the composition of the average granite, and that 

 plutonio rocks are immensely more important than the other classes, 

 even when the term plutonio is used in a much more restricted 

 sense than by many authors. The causes of variation were discussed, 

 and segregation, except as a phenomenon of limited importance, was 

 dismissed as an untenable theory. The origin of the magmas 

 must be considered in order to account for subsequent variation. 

 * Refusion ' seems the only possible mode of formation. Granite 

 appears to result from the effective mixing of the heterogeneous 

 materials melted down, other igneous rocks being the result of the 

 cooling of diil'ereut parts before mixture is complete, basic material 

 having also the best chance of reaching the surface as lava, owing to 

 its superior liquidity. There is circulation of material between the 

 igneous and sedimentary rocks, the material analysed in the latter 

 boing subjected to synthesis in the making of the former. 



VI. — Baviaan's Kloof : A Contribution to the Theory of 

 Mountain Folds. By Ernest H. L. Sohwarz, A.R.C.S. 



1')AVIAAN'S KLOOF is a narrow valley lying between mountains 

 ) belonging to the Triassic period. The geological history may 

 be summarised thus : — 



(o) First base-level. Deposition of Eaou Conglomerate, derived 



