& 



284 Transactions. 



Although this small patch of country has never received much attention 

 from geologists, it has generally been recognized that the rocks of which it 

 is composed are of a different nature from those of the country that lies to 

 the south. The rocks that are in contact with those which are now being 

 considered are of the Oamaru system of marine sediments. Farther to the 

 southward, if one may judge from the nature of the pebbles that are found in 

 the gravels of all the tributary streams of the Wharekahika Stream, the 

 Oamaru sediments are soon succeeded by the Maitai sediments of Trias- 

 Jura age. 



The following are the references that have been made to this country 

 in previous geological work : — 



1869 : Hector's geological map of New Zealand represents them as 



formed of Cretaceo -Tertiary sediments. 

 1873 : McKay, Geological Report, p. xvi. — The map indicates the 



occurrence of trachytic conglomerates throughout this area. 

 1873: Hector's geological map of New Zealand.- — Coal-measures, 



Cretaceous to Miocene. 

 1877: Cox, Geological Report, p. 112. — Trachytes and trachytic 

 agglomerates : " The trachytes in solid flows may be observed 

 continuously until passing Matakaoa Point, Hicks Bay, where they 

 pass by degrees into coarse angular conglomerates." He thinks 

 that the centre of eruption in all probability lay to the seaward of 

 the present coast-line. " They appear to me to be of the same age 

 as the trachytes of Whangarei Heads (andesites), which they resemble 

 in a marked degree, and as they are overlaid by the oyster-bed, 

 which is the lowest member of the Tawhiti series as here developed, 

 they must be at least of Upper Eocene age." 

 1883 and 1885 : Hector's geological map of New Zealand. — Palaeozoic 



sediments. 



1887 : McKay, Geological Report, p. 184. — This geologist went by sea 



from Whangaparao to Awanui. He did not see these rocks, but 



on his map on page 192 he indicates them as acidic volcanic rocks. 



1907 : Marshall, Trans. Aust. Assoc. Adv. Sci., p. 376, states that he 



has not examined any rocks from this district, but in the map 



indicates them as basalts. 



1910 : Park, " Geology of New Zealand." — In the geological map this 



area is coloured as though formed of acidic volcanic rocks. 



1912: Marshall, "Geology of New Zealand." — In the geological map 



the area is tinted the same as those that are formed of basalts and 



andesites. 



This brief resume shows that the rocks have never been accurately 



examined. An opportunity of visiting the district occurred in February, 



1912. Specimens were then collected from the south side of Hicks Bay 



and from the valley of the Wharekahika River, as well as the coast-line 



near Cape Runaway. Mr. E. de C. Clarke also kindly gave me specimens 



that he had collected from the coast-line at Potikirua and Arerotepa. The 



specimens from the valley of the Wharekahika River and Cape Runaway 



were not in situ, but all the others were. On the south side of Hicks Bay 



the volcanic rocks are inter stratified with the limestone of Tertiary age, and 



they evidently represent the products of volcanic activity in relatively 



deep water, judging from the nature of the associated limestone and by 



the absence of oxidized material and of steam-pores in the fragmentary 



matter. Tuff and scoriaceous material is interstratified with the limestone. 



