THE GEOLOGY OF AUCKLAND, 
remember several striking examples which I can mention—as 
the Pupuki Lake on the North Shore ; Orakei Bay in the 
Waitemata ; Geddes’s Basin ( Hopua ) at Onehunga ; and the 
tidal Basin ( Waimagoia ) at Panmure;—Pupuki Lake, believed 
to be bottomless, has been ascertained by Captain Burgess (who 
kindly sounded it at my request) to be only 28 fathoms. I call 
those basins and similar formations, tuff-craters or tuff-cones. 
The excellence of the soil of Onehunga and Otahuhu is owing 
to the abundance of such formations, decomposed strata of 
which form the richest soil that can be met with. It is curious 
to observe how the shrewder among the settlers, without any 
geological knowledge, have picked out these tuff craters for 
themselves, while those with less acute powers of observation 
have quietly sat down upon the cold tertiary clays. 
After the submarine formation of the tuff-craters, the volcanic 
action continuing, the isthmus of Auckland was slowly raised 
above the sea, and then the more recent eruptions took place, 
by which the cones of scoria, like Mount Eden, Mount Wel¬ 
lington, One Tree Hill, Mount Smart, Mount Albert, and Ban- 
gitoto, were formed and great out-flowings of lava took place. 
Many peculiar circumstances, however, prove that those moun¬ 
tains have not been burning all simultaneously. It can easily 
be observed that some lava streams are of an older date than 
others. In general the scoria cones rise from the centre of 
the tuff-craters (Three Kings, Waitomokia, Pigeon Hill near 
Howick.) Occasionally, as in the instance of Mount 
Wellington, they break through the margin of the tuff-crater. 
The Crater System of Mount Wellington is one of the most 
interesting in this neighbourhood, as beautifully shown by the 
large map which Mr Heaphy has kindly prepared for me from 
actual survey. There are craters and cones of evidentlv dif- 
ferent ages. The result of the earliest submarine eruptions is a 
tuff-crater. The Panmure road passes through the tuff-crater, 
and the cutting through its brim exhibits beautifully the cha- 
lacteu.stic outwaid inclination of tliebeds of ashes, elevated from 
then foimei horizontal levels by the eruptions, which threw up 
the two minor crater cones south of the road—one of which is 
now cut into by a scoria quarry. After a comparatively long 
period of quiescence, there arose from the margin of the first crater 
