346 Transactions. — Geologi^. 



The Eiver Manganuku, that runs along the east of the 

 Ruatauiwha Plain, and joins the Waipawa Eiver just below 

 the Waipawa-Hampdeu Bridge, rises in the pumice and con- 

 glomerate hills between Maraekakaho, Kereru, and the Guavas 

 Station. Along the left bank of that stream there is a range 

 of hills, running north-east and south-west, ten miles or more 

 in length, composed of nothing but the Kidnapper pumice- and 

 conglomerate-beds ; and, in order to test the stratigi-aphical 

 position of these beds, I have been over within the last month 

 the entire country between Kaikora and Hampden, and there 

 is no doubt whatever as to the position the beds occupy in 

 relation to the limestones and clay-marls. 



These pumice and conglomerate hills, I believe, ai"e classed 

 as limestones by the Geological Sm-vey, but I shall have occasion 

 to say more upon this point presently, when deahng with Mr. 

 McKay's classification. In some places hereabout the pumice 

 is a sajmon-colour, as at the Kidnappers in certain beds, and is 

 exactly similar to the vast accumulation one sees at Tau- 

 ranga-Taupo, and other places on the eastern side of Lake 

 Taupo. Xow, if aline were taken from the top of the pumice 

 and conglomerates forming the hills on the Hampden-Marae- 

 kakaho Eoad to similar deposits that flank the mountains 

 along the western watershed of the district, it would link 

 together the old area in this direction once occupied b\' de- 

 posits corresponding in every particular with those at Kereru, 

 Dartmoor, Okawa, Pohui, Wairoa, Eedcliffe, Kidnappers, and 

 a dozen otTier places. Further, all those beds would be in the 

 same general plane, except, perhaps, the Kidnappers, which I 

 liave shown in a former paper read before this society * to be 

 connected with a subsiding area that has taken place at a 

 comparatively recent date. 



And now, before referring to the points in Mr. McKay's 

 classification of the rocks in this district to which exception is 

 taken, it will be well to summarise what has already been 

 stated bj me : — 



1. The present watershed of the- district imder notice is to 

 the west, and the slope or present plane of denudation to the 

 east. 



2. This plane of denudation is of recent date, as is shown 

 by the gullet-like valleys through which the rivers run, com- 

 bined with the absence of allu\-ial plains in connection with 

 the several river-basins. 



3. Except towards the west, all the rocks across which 

 the present rivers flow are younger Tertiaries or Post-ter- 

 tiaries. 



i. The so-called high-level gravels of the Geological De- 



* Trans., vol. xxii., pp. 436-7. 



