Geology and Mineixdogy. . 565 



have been issued, accompanied by descriptive pamphlets. The 

 former sheet, described by W. A. Humphrey and H. Kynaston, 

 covers the geology of Pilandsberg and vicinity. A striking- 

 feature of this area is the Pilandsberg range, which is regarded 

 as representing the most important focus of eruption of the 

 ela?olite-syenite magma in South Africa. The three types 

 developed are (1) red syenite, (2) foyaite and lujaurite, and 

 (3) nephelite-syenite. Sheet 13, described by A. L. Hall and 

 H. Kynaston, discusses the geology of the region of Haenerts- 

 burg, which is especially important for its productive gold fields. 



Memoir No. 7 (Pretoria, 1916), by Percy A. Wagner, 

 embraces the geology and mineral industry of the Southwest 

 Africa region, which has changed its political allegiance within 

 recent times. As is well known, the most important production 

 of this country are the diamonds, which amounted in value to 

 £3,500,000 in 1913, exceeding that of Southern Rhodesia for the 

 same period. Since then the production has been reduced, because 

 of over-production, but the territory ranks next to Griqualand 

 West as the most important diamond-producing region in the 

 world, having yielded from 1908 through 1913 over 20 per cent 

 of the total world's production. The special diamond fields are 

 near Luderitz Bay but the detrital diamantiferous deposits extend 

 along the coast for a distance of some 275 miles. There are also 

 rich copper-lead deposits, developed particularly at Tsumeb and 

 other localities. Further some forty large iron meteorites have 

 been found thus far in Great Narnaqualand, similai'ity in the com- 

 position of which leads to the opinion that they may all have 

 resulted from a single meteoric shower. As regards the origin of 

 the diamonds, although kimberlite occurs in the territory, it is 

 considered more probable that the diamonds have been derived 

 from a primary deposit submerged off the coast to the south of 

 Pomona; no definite evidence is available in regard to the nature 

 of this parent rock. Thus far the numerous pipes and dikes of 

 kimberlite are barren of diamonds. 



7. New Zealand Geological Survey, Bulletin No. 17. The 

 Geology and Mineral Resources of the Buller-Mokihinui Sub- 

 division, Westport division ; by Percy G. Morgan and John A. 

 Bartrum. Pp. viii, 210. Wellington, 191 5. — The region described 

 in the present bulletin lies in the central part of the west coast of 

 the south island of New Zealand. It is especially important 

 because of large deposits of high-grade bituminous coal which 

 have been mined for many years. Brown coal and lignite also 

 occur in quantity, and fifty years ago the production of gold 

 from alluvial washings was very considerable. The total output 

 from the bituminous coal mines, from 1877 to 1913, amounted to 

 upwards of 12,000,000 tons. It is recognized, however, that the 

 supplies of the bituminous coal are limited, and will approach 

 exhaustion within 100 or, at most, 150 years. There is prospect, 

 however, that brown coal and lignite may be added to the supply. 

 There has been much question in regard to the age of the New 

 Zealand coal-fields, but it is regarded as settled that the Brunner 



