AUSTRALASIA. 153 



in all excepting the M. Jurassic, Triassic, and Palaeozoic ; coal occurs 

 in the U. Miocene, TJ. Eocene, U. Cretaceous, and M. Jurassic. "W. T. 



HuTTox, Capt. r. W. On the Geological Structure of the Thames 

 Gold Fields. Trans. New Zealand Inst. vi. pp. 272-283. 



The country around Shortland consists almost entirely of trachyte- 

 tufa resting unconformably on Palaeozoic rocks; it is traversed by 

 dykes of dolerite, melaphyre, and timazite, and by auriferous quartz- 

 veins. In the Tapu district the quartz -veins occur both in the Palaeo- 

 zoic slates and in the trachyte -tufa, but chiefly in the latter. At 

 Coromandel the veins are all in the tufa. Prof. Hochstetter considers 

 that the gold was derived only from the Palaeozoic slates, whilst Dr. 

 Hector contends that it occurs neither in the slates nor in the tufa, but 

 in an older volcanic formation between the two, and which has partaken 

 in the movements of the Palaeozoic slates. Capt. Hutton denies the 

 existence of this intermediate volcanic formation, considering it part of 

 the trachytic tufa, and regards the gold as derived from the latter. 



The results of the survey of the Thames gold-fields are : — 1. That no 

 line of separation can be drawn showing the existence of two volcanic 

 formations separated from one another by a long period of time. 2. 

 That the rock in which the auriferous veins are found does not run in 

 nearly vertical bands, but is lying in its original (nearly horizontal) 

 position. 3. That all the phenomena are consistent with the idea that 

 the formation is one, the older portions forming the centre and the 

 younger the outskirts. Seams of coal have been found at Coromandel, 

 overlain by trachyte and trachytic agglomerate, which at one place 

 contains gold. Both the trachytes and the dykes resemble the Miocene 

 gold-bearing rocks of Hungary. Those of the Thames gold-fields are 

 considered to be Oligocene, not older than the Wiatemata series. 



R. E., Jun. 



. Keport on the Geology of the North-east Portion of the S. 



Island, from Cook's Straits to the Rakaia. Reports of Geological 

 Explorations during 1872-3 ; Geol. Surv. New Zealand, pp. 27- 

 58 (with map and sections). 8vo. Wellington. 



The geological features of a tract of 11,000 square miles are described. 

 A band of Palaeozoic rocks extends across from N.E. to S.W., forming 

 mountain-ranges. It is divided into two conformable formations : — 

 Tuamarina Formation, consisting of phyllites, quartzites, chlorite 

 schist, sandstones with Orthoceras and Fhragmoceras (?), and conglo- 

 merates. KaiTcoura Formation with Annelide markings. 



Planking this Palaeozoic band, both on the N.W. and S.E., is a series 

 of Secondary deposits, viz. Wairoa Formxition (U. Trias), with Monotis 

 salinaria, &c. Maitai Formation (L. Jurassic), with interbedded vol- 

 canic rocks. Putataha Foi'mation (M. Jurassic), with coal-seams and 

 obscure plant remains. Waipara Formation (U. Cretaceous), in two 

 divisions : — a. Ngarara group, with contemporaneous volcanic rocks 

 and the coal-fields of the Malvern Hills ; Saurian remains : h. Amuri 

 Limestone group. 



