Marshall. — Geology of North Island. 87 



The general features of the physiography of the whole dis- 

 trict were, of course, fully outlined by Hochstetter,* who travelled 

 throughout the district in 1864. The general results of his work 

 require no very great modification, though, of course, there 

 has been much change in the Tarawera and Rotomahana dis- 

 trict as a result of the eruption of 1886. 



Another description has been given by Marshall! and by 

 Gregory. J Cussen§ has written papers on the changes in the 

 course of the Waikato River, as well as a paper on the country 

 to the west of Taupo, that is still very imperfectly known. 



McKay 1 1 has lately discussed the locality of the eruption, 

 from which all the pumice was dispersed. 



In regard to the age of the outburst of volcanic action in 

 this part of New Zealand, we have Hill's^f statement that there 

 is a pumice-bed interstratified with Miocene (Cretaceo-tertiary} 

 clays at Tolaga Bay. Park** states that the activity of Rua- 

 peliu and Egmont began in the newer Pliocene. In the Thames 

 district Parkff gives the Upper Eocene age for the commence- 

 ment of volcanic action. Hectorff states that the Thames 

 andesites are of Cretaceo-tertiary age. Hutton§§ places the 

 Thames andesites doubtfully in the Oligocene, and the volcanic 

 rocks of the central region in the Pliocene. Afterwards |||| he 

 states that the eruptions began in the Miocene. 



In this paper an attempt will be made to combine the results 

 obtained by the various authors named above with the observa- 

 tions made by the author of this paper. 



Age. 



A recent paper by Professor Park^j has revised the classifica- 

 tion of the Cainozoic rocks of New Zealand. Nearly all the 

 Cretaceo-tertiary rocks of Hector, as well as his Eocene rocks, 

 are referred to the Miocene as a result of a fresh examination of 

 typical sections. If this reasonable conclusion is adopted, an 



* Hochstetter, " New Zealand," 1867. 



f Marshall, " Geography of New Zealand," p. 73 et seq. ; Whitcombe 

 and Tombs, 1905. 



X Gregory, " Australasia," vol. i, pp. 577-82 ; Stanford. 



§ Cussen, Trans. N.Z. Inst., vol. xx, p. 316; vol. xxvi, p. 398. 



|| McKay, Mines Reports, 1899, p. 16. 



If Hill, Trans. N.Z. Inst., vol. xx, p. 304. 

 **Park, Geological Reports, 1886, p. 71. 

 ft Park, " Hauraki Goldfields," p. 13. 

 XX Hector, " Outline of New Zealand Geology," p. 87. 

 §§ Hutton, " Geology of New Zealand," Quart. Journ. Geol. Soc, 1885, 

 p. 192. 



Illl Trans. N.Z. Inst., vol. xxxii, p. 172. 

 ifjfPark, Trans. N.Z. Inst., vol. xxxvii, p. 491. 



