296 Transactions. — Geology. 



Tarawera, midway between Napier and Taupo, where the same 

 tracbytic-lava rocks are to be seen as are met witb throughout 

 the whole of the central volcanic district extending from the 

 Paeroa Mountains to Runanga, a place situated on the Tarawera- 

 Taupo Koad. At the latter place the trachytic-lavas are seen 

 to form the bed of the Waipuuga Stream ; (2nd) at Ked Island, 

 some miles along the coast to the south of Cape Kidnappers, 

 where Mr. McKay (" Geological Keports, 1874-76," p. 45,) says 

 igneous crystalline rocks occur ; (3rd) at Woodville, in the 

 Seventy-mile Bush, where a hard compact reddish rock, with a 

 cellular and scoriaceous surface- structure is met with in a small 

 creek which runs through the grounds adjoining the public 

 school. The rock appears to be a variety of trachyte. Pos- 

 sibly other igneous rocks will be found as the country south by 

 east and south-east of Tarawera becomes better known, where I 

 imagine is the termination of the great lava stream which at 

 one time occupied a large portion of the valley through which 

 the Waipunga Stream and its numerous tributaries now flow. 

 Indeed, I should not be surprised if the trachyte-lava rock is 

 eventually found underlying the lowest beds of blue-clay marls 

 which are to be met with in some places flanking the east slopes 

 of the central mountain range, as in the Tukituki and Ngaru- 

 roro Rivers. But though the evidence of the existence of volcanic 

 rocks is so very limited — and there are no traces whatever of 

 eruptive vitreous rocks except at Tarawera and Woodville — the 

 whole country bears the evidence of having been greatly 

 modified even in its surface-features by volcanic products known 

 as ejectamenta. 



The geology of the district under notice has been in great 

 part already described by the Geological Survey Department ; Mr. 

 Percy Smith, Assistant Surveyor- General, has also published 

 a report in the " Transactions," vol. ix., p. 565, on the " Geology 

 of the District between Napier and Mohaka." The results, 

 though necessarily imperfect and incomplete, show that the 

 district, though offering examples of Mesozoic and even of 

 Paleozoic rocks, is essentially a Tertiary and Post-tertiary one, 

 and offers ample testimony of vast movements, which have been 

 brought about mainly by the action of water. According to the 

 geological map published with the "New Zealand Handbook " 

 by Dr. (now Sir James) Hector, the Director of the Geological 

 Survey, a large proportion of the rocks exposed along the coast 

 between Tologa Bay and Cape Turnagain belong to what are 

 known in this country as the Cretaceo-tertiary formation. The 

 older Tertiaries, known as Eocene and Miocene, are shown on 

 the map to lie immediately to the west of the so-called Cretaceo- 

 tcrtiaries, both to the south and north of Napier. Between 

 Tiwhinui, a few miles to the south of the Mohaka River mouth, 

 and Cape Kidnapper in the Hawke's Bay river system, the 



