270 Reviews — Geological Survey of New Zealand. 



4 miles to one inch), showing areas of granite, ferruginous quartz- 

 schist, quartz reefs, and greenstones with undifferentiated metaniorphic 

 rocks (Auriferous Series). Some photographic views and sections 

 are inserted in the text, and appended is a petrographical description 

 of some rocks from the vicinity of Lake Giles, by Mr. R. A. 

 Farquharaon. The rocks comprise gabbro, epidiorite, amphibolite, etc. 



Bulletin No. 46, 1912, contains " A General Description of the 

 Northern Portion of the Yilgarn Goldfield and the Southern Portion 

 of the North Coolgardie Goldfield", by Mr. Harry P. Woodward. 

 The object of the report is to indicate those tracts of country to 

 which prospectors are advised to devote attention, and also those 

 to be avoided, such as certain large sand-covered granite areas. 

 Information is given on the evidence to be gathered from the 

 soils and surface features, and also on tlie important matter of 

 water-supply. 



Bulletin No. 50, 1912, is on " The Geology and Mineral Industry of 

 Western Australia ", by Mr. A. Gibb Maitland and Mr. A. Montgomery. 

 This is a useful guide, giving a summary of what is known of tlie 

 geological formations, and of the economic geology, included under 

 the headings of gold, copper, lead, tin, tantalum, iron, coal, salt, 

 phosphate deposits, and artesian water. Information is also given 

 with regard to the mining and occupation of mineral lands. 



VI. — Geological Sukvey of New Zealand. 



" ri^HE Geology of the' Waihi-Tairua Subdivision, Hauraki Division " 

 J. forms the subject of Bulletin No. 15 (new series), 4to, 

 Wellington, 1912. The area, whicli is described by Dr. J. M. Bell 

 (late Director) and Mr. Colin Eraser, constitutes part of the eastern 

 coast of Hauraki, in the northern portion of the North Island of 

 New Zealand. 



With the exception of the superficial deposits the country is formed 

 of a complex of volcanic rocks, which probably were extruded through 

 a foundation of Jurassic or older rocks, none of which are exposed in 

 the Waihi-Tairua Subdivision. The volcanic rocks form a series 

 (1) of andesitic and dacitic lavas and breccias of Upper Eocene or 

 Miocene age, (2) of somewhat similar bi;t more fragmental materials 

 and more glassy lavas of Miocene age, and (3) of rocks mostly 

 rhyolitic, with dacitic tuffs, breccias, and lavas of Pliocene and perhaps 

 later times. Many dykes of andesite and dacite pervade the lavas, 

 and the rocks have been much altered by hydrothermal action. 

 Among the rhyolites a brecciated flow-rock locally known as 

 'Wilsonite' is used as building-stone and road-metal. 



Mining is the principal industry in the region, and the metalliferous 

 areas of gold with silver appear to be limited to the Eocene and 

 Miocene series (1 and 2). Inthe Waihi Gold-field the more productive 

 part is within a large intrusion of dacite. Gold-bearing quartz-veins 

 occur in the volcanic rocks. The first discovery of gold in New 

 Zealand was made in 1852 in the Coromandel Subdivision, to the 

 north-west of the area now described. At Waihi the yield in 1910 

 was a little more than one million pounds worth of bullion. 



