288 I'rditsdcfiuns. 



Art. XXXIV. — Napier to Runanga and the Taupo Plateau. 

 By H. Hill, B.A., F.G.S. 



[Bead before the Haivke's Bay Philosophical Instihite, 24th June, 1910.] 



Although a good deal has been written about the volcanoes of New Zea- 

 land from the time when Hochstetter paid his celebrated visit in 1859, very 

 little is yet known of the Taupo Plateau and the rocks that either bound 

 it on the east or are found upon it here and there in exposed areas. Hoch- 

 stetter and the late Sir James Hector, F.R.S., issued maps of the so-called 

 volcanic district, but they were theoretical rather than actual, as the larger 

 portions of the district were not visited by either of these careful observers. 



Few other places in the world present better opportunities for obser- 

 vation of volcanic phenomena of the present-day type than does the area 

 embraced mainly within the Taupo-Waikato basin ; but this constitutes 

 only a small portion of the area that is geologically included within the true 

 volcanic zone. 



The paper by Dr. Marshall (Trans. N.Z. Inst., vol. 40, p. 79) on " The 

 Geology of Centre and North of North Island," and the descriptive account 

 of the volcanic cones south of Lake Taupo by Mr. Speight, B.Sc, F.G.S., 

 in the admirable botanical-survey report of the Tongariro National Park 

 by Dr. Cockayne, have given increased importance to the volcanic district, 

 but much remains to be done before complete information can be made 

 available covering the geological history of this interesting district. 



The key to the physical evolution of the North Island is to be found in 

 the true interpretation and history of the volcanic area. 



In company with the Director c^the Dominion Museum, Christmastide 

 was spent in studying that portion of the Taupo Plateau extending from 

 Runanga to the Rangitaiki River, thence to Loch Inver Station, on the 

 northern slopes of the Kaimanawa Range, finishing at Taupo. This work 

 I had another opportunity of reviewing at Eastertide, being anxious to 

 complete a geological section along the coach-road from Napier to Taupo. 

 This section (fig. 1) shows the beds to be met with between the sea-beach 

 at Petane, where the coach-road strikes inland, and Taupo ; but the sec- 

 tion is continued to Karangahape Head, on the west side of the lake, as 

 the intention is to give in another paper a similar section from Whakatane 

 to Ruapehu, through Lake Taupo. Fig. 2 gives a map of Lake Taupo to 

 scale, with the most important geological features. 



A reference to fig. 1 shows Pliocene beds of Napier upper limestone 

 near the Motor Company's stables at Petane. These in places are over- 

 topped with shingle conglomerate representing the Kidnapper shingle con- 

 glomerates. The middle beds of the Pliocene series appear up the hill 

 before reaching an elbow in the road, where again the shingle conglomerates 

 top the limestones. No change takes place in the general characters of the 

 Middle Pliocene series through the whole length of the Esk Valley ; but 

 the overlying shingles, sometimes mixed with sand, become thicker and 

 thicker, and on the left bank of the river they are seen dipping to the south- 

 east as strong conglomerates. On the right bank here and there the same 

 beds appear, but there are Recent river-gravels mixed with limestone and 



