282 SCIENCE PROGRESS 



fication is connected with the escape of water from the rock 

 very soon after solidification. 



The petrography of Angola has been dealt with recently in 

 two papers. A. Holmes (Geol. Mag. (VI) 2, 1915, 228, 267, 

 323, 366) describes many interesting alkaline rocks including 

 aegirine-riebeckite-granite,^ nepheline-syenite, nepheline-phono- 

 lite, nepheline-monchiquite, and a camptonitic tinguaite which 

 is identical with Marshall's ulrichite from New Zealand. These 

 rocks come from Loanda, the northern province of Angola. 

 The petrology of Benguella, the central province, has been 

 described by the author from a rock collection made by Prof. 

 J. W. Gregory (Traits. Roy. Soc. Edinburgh, 19 16). The rocks 

 include a probably Archaean basement consisting mainly of 

 igneous gneisses, intruded by a charnockite series identical with 

 that of Peninsular India, and also by a curious series of horn- 

 felsed cassiterite-bearing porphyries. These rocks are intruded 

 by batholiths of non-foliated granites and granodiorites, the 

 latter with cassiterite. A thick series of ancient rhyolites occur 

 in the Oendolongo Mountains. In the Ochilesa district there 

 is a series of alkaline rocks including nepheline-syenite, sodalite- 

 syenite, akerite, shonkinite, tinguaite, solvsbergite, and ouachi- 

 tite, which are probably of Cretaceous or Tertiary age, and 

 comparable with the similar series of Loanda described by 

 Holmes. 



H. S. Washington has made a quantitative study of Holland's 

 charnockite series from Madras (Amer. Journ. Set. 1916, 41, 323), 

 and has corrected the earlier unsatisfactory chemical analyses. 

 He shows that there are at least five or six comagmatic regions 

 of ancient plutonic rocks of the " charnockite " character. (A 

 seventh has been added in Angola, see above.) 



The topaz-bearing rocks of Gunong Bakau, Malaya, intruded 

 as veins into granite, have recently been described as of primary 

 igneous origin, but W. R. Jones (Geol. Mag. (VI), 191 6, 3, 255) 

 brings forward strong reasons for the secondary origin of the 

 topaz and cassiterite in these rocks, and for their correlation 

 with the similar occurrences of other tinfields. 



A detailed account of the volcanic rocks of South-eastern 

 Queensland, with twenty-five new chemical analyses, is given 

 by H. C. Richards (Proa. Roy. Soc. Queensland, 1916, 27, 105- 

 204). These rocks consist of rhyolites, trachytes, dacites, 

 andesites, and basalts, and are believed to be of Kainozoic age. 



