Revieivs — Moonta and Wallaroo, South Australia. 89- 



view, and in this collection full advantage has been taken of this 

 point by Dr. Anderson. However, the photographs of the craters 

 of La Soufriere and Bromo are notable exceptions to the above 

 statement and give the general form of these craters to perfection. 



Unfortunately, Dr. Anderson never returned from his last journey 

 to the East, as he was taken ill on his way home with enteric fever, 

 from which he died and was buried at Suez. However, Professor 

 Bonney is to be congratulated on giving to the world this collection 

 of his photographs, which will be of the greatest service to all 

 geologists and especially to those who are not so fortunate as to be 

 able to go out and see the actual volcanoes themselves. 



W. H. "WlLCOCKSON. 



lY. — The Geology of the Moonta and Wallaeoo Mining District, 

 South Australia. By R. L. Jack. Geological Survey of South 

 Australia, pp. 135, with figures, folding maps, and sections. 

 Adelaide, 1917. 

 rilHE mines of the Moonta and Wallaroo area, on Spencer Gulf, are 

 X responsible for a very large proportion of the copper production 

 of South Australia: up to the end of 1916 they had yielded copper 

 to the aggregate value of over £19,000,000. This memoir gives 

 a remarkably clear and well- written account of the geology of an 

 area which is interesting both from its great economic importance 

 and from its bearing on general petrological problems, and especially 

 on the question of the differentiation of igneous magmas. The 

 formations present are Precambrian, Cambrian, and Tertiary, together 

 with a thick cover of recent deposits. The Precambrian series 

 consists of highly altered sediments of various kinds, basic and acid 

 igneous I'ocks, and a large mass of felspar-porphyry, Avhichis probably 

 intrusive in the foregoing : the whole of these are cut by granites 

 and pegmatite dykes, also of Precambrian age. The productive lodes 

 of the Moonta area are found in pegmatite dykes cutting the felspar- 

 porphyry. They do not pass up into the Cambi'ian strata. The 

 Cambrian rocks are not of mucli interest, and only a few small patches 

 now remain. The Tertiary rock is a thin white or buff limestone, 

 with fossils ; the character of these is not stated in the report. 

 A large part of the country is occupied by a so-called travertine of 

 recent date : this is obviously similar to the surface limestones of 

 South Africa. Along the coast and also in certain inland areas is an 

 extensive development of sand-dunes. 



The pegmatites of Moonta consist of quartz, microcline, andbiotite, 

 with a considerable number of peculiar minerals, especially hjematite, 

 tourmaline, ferberite, scheelite, molybdenite, galena, smaltite, 

 blende, and apatite. By far the most important copper minerals are 

 chalcopyrite and bornite. At the surface is an oxidized zone about 

 100 to 150 feet in depth, with a variety of oxides, sulphates, 

 carbonates, and chlorides of copper and other metals. Below the 

 leached caps of the lodes is a zone of native copper : this feature is 

 difficult to explain. The lodes of the Wallaroo area are found in the 

 ancient sediments, and are less well defined than those of Moonta, 



