264 ORIGIN OF KAXD IJANKETS. 



which, indeed, shows a Karroo type of laccohte cut down, we 

 infer that beneath the Karroo there is a central sohd laccohte 

 into which has been poured the more siliceous material dissolved 

 out of the sedimentary rocks by the dolerite dykes. 



To look at the matter from another standpoint. The 

 dolerite dykes imply the inbringing of new material, and new 

 matter thrust into the crust means that the crust must have been 

 pushed aside. In the Karroo laccohte, as in the Transvaal one. 

 the thrust has taken effect in the south Qnly, and the crust has 

 been shifted southwards. But as the volume augmentation on 

 the level of the dolerite sills and dykes is comparatively nil, 

 whereas lower down there must have been considerable addition, 

 the major thrust would be considerably below the level of the 

 dolerite sills and dykes; therefore, all folds produced by the 

 great Karroo laccohte should show an inclination away from the 

 laccohte, and such, in fact, do we find. All the main folds of the 

 Cape coastal mountains incline towards the sea, especially where 

 they lie huddled together inside the granite bosses of the coast 

 belt, as may be seen in the Robinson Pass between Mossel Bay 

 and'Oudtshoorn. That there has been a thrust from the interior 

 is proved in exactly the same way as round Pretoria, for where 

 the line of granite bosses comes to an end at George, the folds 

 splay out to the south-east, and the last boss of granite has itself 

 beeen carried forwards by the movement. Could we plane off the 

 Cape Colony to sea-level, wc should find the same conditions as 

 in the Transvaal — a great laccohte surrounded with a fringe of 

 sills, .and to the ^outh a very ihick area of quartzites in which one 

 particular bed would be repeated again and again as in the 

 bankets in the upper Witwatersrand Beds. 



Research Grants.— Applicants for grants in aid of 

 scientific research are asked to forward their application forms, 

 properly filled up. not later than the ist July, 191 2. to Prof 

 J. C. Beattie. Honorary Secretary of the Royal Society of 

 South Africa, at the South African College. Cape Town, from 

 whom the necessary application forms may be obtained. 



Radioactivity and Molecular Structures. 



At a recent meeting of the Cambridge Philosophical Society. 



Prof. W. A. D. Rudge. of Grey College. Bloemfontein, described 

 some experiments made by him in the Cavendish laboratory to 

 ascertain whether intramolecular changes occurring in the con- 

 version of magnetic into non-magnetic nickel, and of acidic into 

 basic iron, were accompanied by development of radioactivity 

 The conclusions arrived at were entirely negative. 



