552 Reviews — New Zealand Geology. 



3. Additional Facts concerning the Distkibution op Igneous 

 E,oce;s in New Zealand. By J. A. Baeteum. Trans. New 

 Zealand Inst., vol. slix, pp. 418-24, with 1 plate and 1 text- 

 figure, 1916. 



rilHIS paper contains petrographical descriptions of nine specimens 

 X of igneous rocks from different parts of New Zealand, including 

 both plutonic and volcanic types. A liypersthene basalt from near 

 Whangarei is believed to be the first instance of this rock from that 

 country, although hj-persthene is well known in the basic andesites 

 of Tarawera and Tongariro. A peculiar basalt with olivine, augite, 

 and large phenocrysts of biotite from tbe Wairoa River is often used 

 for ornamental work and is locally called " Kaipara granite". 

 A hornblende basalt is also noted from near Sumner in the South 

 Island. Tlie plutonic rocks include a coarse-grained troctolite with 

 much serpentine from Wade, near Auckland, and various gabbroid 

 and dioritic rocks from tbe Baton and Graham Rivers, Nelson. These 

 are essentially very coarse-grained hornblende rocks with much 

 ilmenite, epidote, apatite, sphene, and a varying amount of quartz : 

 the hornblende seems to be secondary after pyroxene. Some 

 boulders of dioritic rocks with gneissic structure were found at 

 Albany, near Auckland: they probably come from a Miocene 

 boulder-bed. Diorites seem to have formed an important element in 

 the pre-Tertiary terrain of the Auckland district. A specimen of 

 granodiorite from Reef ton, in the Nelson district, which was 

 apparently collected from a river gravel, is remarkable in that it 

 contains what appears to be primary epidote. It is a rock of granitic 

 appearance, with abundant biotite and a large variety of felspars, 

 including perthite, microcline, and plagioclase. Both sphene and 

 epidote are very abundant. The epidote, often occnrs in well-formed 

 crystals enclosed in felspar or in biotite. Crystals of brown horn- 

 blende are often enclosed in the epidote, and the author regards 

 the primary character of some at least of the epidote as established. 



Although the rocks here described come from widely scattered 

 localities and may be of very different ages, nevertheless they all 

 show more or less clear sub-alkaline characters. One specimen only, 

 from Wairau Creek, Milford, Auckland, is described as a trachyte, 

 and even this does not seem to be a A^ery alkaline rock. However, 

 no analyses are given, so that this point cannot be decided. 



R. H. R. 



4. The Yolcanic Roces of Oamaru. By G. H. IIttlet. Trans. 



New Zealand Inst., vol. 1, pp. 106-17, 1918. 



IN this district there are three horizons of volcanic rocks — the 

 Waiareka tuffs, the Kakanui breccia, and an upper lava, the latter 

 shows many of the characters of the pillow lavas, but they cannot 

 be classed with the spilites, since the proportion of soda-felspar is very 

 low. It was, however, erupted under marine conditions, but in 

 shallow water. The stratigraphical breaks and the limestone 

 conglomerate can be explained on the assumption that volcanic 

 islands were rapidly formed and rapidly destroyed : hence the un- 

 conformities introduced into the Oamaru system by other observers 



