Geological Society. 73 



clearly defined boundaries, sometimes melting away into the surround- 

 ing mass, generally finer in grain than the latter. After a sketch 

 of the literature of the subject, the author described the results of 

 chemical and microscopic investigations of these patches in the 

 granites of Cornwall, Snap Pell, Aberdeen, Peterhead, Port William, 

 and North-eastern Ireland. There are two classes of inclusions : — 

 (1) the result of the abnormal aggregation of the minerals consti- 

 tuting the granite itself, containing generally more plagioclastic 

 felspar, mica, or hornblende than it, with some other distinctions, 

 most probably concretions formed contemporaneously with the soli- 

 dification of the mass ; (2) fragments of included schistose or slaty 

 rock, often not very highly altered, caught up from the rock-masses 

 through which the granite has forced its way. 



3. " Certain Geological Pacts witnessed in Natal and the Border 

 Countries during nineteen years' residence." By the Eev. George 

 Blencowe. Communicated by the Eev. H. Griffith, P.G.S. 



Shales and sandstones are the prevalent rocks from the coast for 

 about twenty-four miles inland. Here is a protrusion of granite ; 

 beyond the sandstones come ferruginous shales, with scattered 

 boulders of trap on the surface. The northern third of Natal is 

 white sandstone, formed into hills and ridges by denudation, with 

 a long trap- capped plateau near Helpmakaar. Coal-seams occur 

 in the sandstones. There are frequent vertical pipes in these sand- 

 stones, which, the author thinks, mark the site of trunks of trees, 

 round which the sandbeds had accumulated. Eorke's House and 

 Isandhlwana are near the above plateau. Near the former is an 

 extinct mud-volcano. A remarkable " vitreous shale " is found near 

 the Buffalo ; isolated pinnacles of it occur at the spot where the few 

 survivors of the fight crossed that river. A range of mountains, 

 with mural escarpments, remnants of an ancient plateau, rising to a 

 height of some 2000 feet above another plateau which is 5000 to 

 6000 feet above the sea, extends for about 500 miles from the north 

 of Natal to near Cradock in the Cape colony ; they are sandstone 

 horizontally stratified, capped by trap. Some other geological 

 features are described. The Transvaal consists of undulating hills 

 of soft limestone, a sandstone range, and a country rich in metals ; 

 iron-ore, cobalt, nickel, copper, and gold occur, as well as plumbago. 



December 3. — Henry Clifton Sorby, Psq., P.E.S., President, in the 



Chair. 



The following communications were read : — 



1. " The Gneissic and Granitoid Pocks of Anglesey and the 

 Malvern Hills." By C. Callaway, M.A., DSc, P.G.S. ; with an 

 Appendix on the Microscopic Structure of some of the Eocks, by 

 Prof. T. G. Bonney, M.A., P.E.S., Sec.G.S. 



The author described the results of his investigations into the 



