iS94- 



NOTES AND COMMENTS. 87 



Geology of New Zealand. 



The Minister of Mines for New Zealand has recently issued his 

 statement for 1892-3 (Wellington: 1893). The only portion of any 

 scientific interest is an account by Mr. Alexander McKay of 

 "Geological Explorations of the Northern part of Westland " (pp. 

 132-186). The country of Westland is on the west coast of the 

 province of Canterbury, and includes the western slopes of the 

 Southern Alps, and the lower grounds between the mountains and 

 the sea from the Grey River to the northern boundary of Otago. The 

 rocks exposed in the district, as shown on the geological map that 

 accompanies the paper, are of very varied ages and character ; they 

 include Quaternary and Tertiary gravels, clays and sands, a whole 

 series of Cretaceo-Tertiary hmestones, sandstones, and marls, some 

 diabasic ash-beds apparently of Triassic age. Carboniferous slates, 

 slightly metamorphosed Devonian rocks, and other metamorphic 

 and igneous rocks of which the age is uncertain. 



While considering the disposition and origin of the auriferous 

 gravels for the practical purpose of gold mining, Mr. McKay finds it 

 necessary to investigate the former distribution of land in this portion 

 of the South Island, and he concludes that all its great physical 

 features are of Pliocene or post-Pliocene origin. He believes, indeed, 

 " that a mighty mountain-range rose from the sea, possibly towering 

 to heights far above the limits of eternal snow, since the Miocene 

 period, and that its central and western parts were subsequently 

 depressed, till the ocean removed or now rolls over its highest 

 peaks." And he supposes that these changes took place as 

 follows : — " During Tertiary times, up to the close of the marine 

 deposits of the Miocene period, New Zealand was greatly 

 depressed, and by far the greater part of its present area 

 was below the level of the sea. At the period of greatest 

 depression. Von Haast sketches us the South Island as consisting of 

 a line of rock-islets formed by the outstanding higher peaks of the 

 main range of mountains ; but it is not clear that even these stood 

 above the water-level. And if it be contended that a consideration 

 of the fauna and flora of these islands at the present day, in com- 

 parison with what characterised former geological periods within the 

 same area, necessitates the uninterrupted existence of land, it does not 

 follow that this land must have been the crest of the Southern Alps. 

 Such land may have lain to the westward of the present coast-line, 

 but more probably it lay to the eastward in the line of the older axis 

 of New Zealand, trending in a N.W. and S.E. direction. The N.E. 

 and S.W. hne of elevation is modern compared with this other, and 

 probably was but feebly marked prior to the elevation at the close of 

 the Miocene period." 



In a previous report (1890-91, p. i), Mr. McKay has dealt with the 

 mode of appearance of the main chain and other mountain ranges of 

 the northern and central parts of the South Island. " The manner in 



