Hurrox.—On the Age of the Orakei Bay Beds. 811 
the Parnell grit dips southerly and reaches the sea-level some distance from 
the head of the bay, so that all the rocks at the head of the bay must lie 
above it. On the west side of the bay the Parnell grit is not seen ; and, in 
my opinion, it either thins out or passes below the Point Britomart beds. 
As, however, the section has two breaks, one in St. George's Day and the 
other in Mechanie's Bay, nothing certain can be made out; but it is worthy 
of notice that the beds above the Parnell grit on the east side of St. George's 
Bay eontain plant remains, as also do those at Point Britomart. Next, 
with regard to Mr. McKay’s first statement: To the east of Parnell, be- 
tween Resolution Point and Hobson's Point, there is a break across Hob- 
son's Bay, a mile in length, in which nothing definite can be seen. It is, 
therefore, quite impossible for any one to say, from stratigraphical evidence, 
whether the beds at Hobson's Point are above or below the horizon of the 
Parnell grit, and consequently whether they are or are not the equivalents 
of the Point Britomart beds. It is indeed probable that, on the whole, the 
rocks of the Waitemata series get younger to the westward ; but, although 
usually nearly horizontal, they are subject to strong local disturbances—as 
at Cape Horn, Freeman's Bay, Wangaparoa, and Parnell,—and it is as 
likely as not that the very oldest beds in the series may have been brought 
up at Parnell. 
Neither can Mr. MeKay produce any evidence of an unconformity below 
the Parnell grit.: He says, ‘‘ Respecting the question of an unconformity 
between the Orakei Bay beds and the higher miocene rocks, I should submit 
that, when estuarine muds and soft sandstones are suddenly succeeded by 
coarse volcanic agglomerate, there is, by whatever degree the unconformity 
is measured, most surely unconformity to a certain extent; and when it is 
determined that the beds above and below belong to different groups of 
formations— e.g., the cretaceo-tertiary and the miocene—although no strati- 
graphical unconformity were apparent, the conclusion that there is such 
cannot be escaped." * Accordingly in his section from ** Auckland north to 
Wade" he shows the Parnell grit highly unconformable to the underlying 
beds. The idea that an outbreak of voleanic energy must necessarily mark 
an unconformity may be passed over in silence; but if Mr. McKay had 
proved that the two sets of beds belonged to two different formations of very 
different ages, then all would allow that an unconformity was probable 
although it might not be apparent. But this is just what Mr. McKay has 
not done. He recognizes the few fossils found north of Lake Takapuna, 
above a bed supposed to be the Parnell grit, as miocene, and says that they 
differ from those found at Orakei; but he makes no reference to the fact 
that Mr. Cox had found the Orakei fossils mixed with miocene shells a 
* Le. p. 106. 
