Fox. — The Waitemata Series. 489 



west was observed. The dip of the sandstones near 2 is 

 not actually seen. The grit here is about 8 ft. thick. 

 Lapilli, however, are rare in it, and in some respects its 

 general appearance does not resemble that of the grit. This 

 may be due simply to the fact that it is a very westerly 

 outcrop. On the other hand, it is possible that the bed seen 

 here is a distinct one, possibly an outcrop of the Ponsonby 

 tuff, to be presently described. 



7. The other Volcanic Beds. 



Having dealt at length with the Cheltenham breccia and 

 the Parnell grit, something must be said of the other volcanic 

 beds. I have already said that I do not consider the coarse 

 breccias containing Bryozoa as all identical beds, but find 

 it impossible at present to distinguish between them. The 

 finer tuffs of the same, or nearly the same, age may, however, 

 be separated. Two of them are here described as the Wairau 

 tuffs and the Ponsonby tuff. I should also mention that 

 other beds contain occasional volcanic fragments, but not 

 enough to constitute them tuffs. The Orakei greensand is a 

 very good instance, for in that bed patches of scoriaceous 

 lava the size of a pin's head may be detected with a lens. 

 On the shores of the Tamaki, near Panmure, there are also 

 pumice sands, but I believe these are Pliocene or later beds, 

 unconformable to the Waitemata series, and derived from the 

 pumice plateau in the centre of the North Island. 



The Waitakerei breccias and conglomerates on the west 

 coast and therefore on the other side of the vents, I have 

 not visited ; but they must, I believe, be classed with the 

 Waitemata series. 



It is interesting to compare the Wairau tuffs with that 

 formed at the eruption of Tarawera. Except that the former 

 were submarine, the resemblance is considerable ; but, judg- 

 ing from their thickness and distance from the vent, the 

 eruptions which produced them were larger. It is interesting 

 to note that there are three or four tuffs separated in each 

 case by a few inches of shale, so that the eruptions succeeded 

 each other at only short intervals. These eruptions took 

 place some time after those which produced the Cheltenham 

 breccia, and were not, apparently, so violent. 



Wairau Tuffs. 



I have given this name to volcanic beds which are best 

 developed at the Wairau Creek, near Lake Takapuna. There 

 are really several beds, each separated from the next by a 

 thin layer of shale. The distinction between a tufaceous 

 sandstone and a sandy tuff is not very easy to draw, and some 

 of these beds are decidedly sandy. The lowest, however, is 



