ft 
231 
of sandstone and shale, lava-debris, cinders and scorise (lapilli), 
which now form beds of volcanic agglomerate or tuff. The erup- 
tions occurred, no doubt, at intervals; for in this manner alone 
can the fact be accounted for, that the ejected material has 
been deposited round the point of eruption in layers one above 
the other , forming low hills gradually rising 
and with a circular basin or dish-shaped crater 
in the middle. A cross-section presents clearly 
the different layers, which usually slope in- 
wards towards the bottom of the crater, as 
well as outwards down the sides. The hills 
formed by these first eruptions we may de- 
signate as tuff-cones , or in as much as they enclose circular 
craters, as tuff-craters. 
Lake Pupuke on the Nortlishore, Orakei Bay East of Auck- 
land, Geddc’s Basin (Hopua) near Onehunga, the Waimagoia Basin 
near Panmure, the Kohuora Hills, South of Otahuhu, and a good 
many others are striking examples of such tuff-craters. Like the. 
lake-craters ( cc Maare of the Eifcl, the crater-basins are sometimes 
very deep and full of water, — the fresh- water Lake Pupuke lias 
a depth of 28 fathoms, 1 — sometimes flat and dry, or covered 
only with swamp and turf-moors. Where they lie close to the 
sea, the latter has generally forced an entrance on one side 
or the other, breaking down the circumvallation , and thenceforth 
passing in and out from the crater-basin. Where there are several 
such cones close together, as at Onehunga, and in the vicinity of 
Otahuhu, it is very often a difficult matter, to designate the in- 
dividual craters , because a space bordered by a number of craters, 
very easily assumes for itself the form of a crater. 
The excellence of the soil of Onehunga and Otahuhu is owing 
to the abundance of tuff-cones,. Nearly each one of them harbours 
1 According to Captain Burgess, pilot of the Waitemata Harbour. The na- 
tives, however, sustain the peculiar notion or legend, that the opposite volcanic 
cone, the Rangitoto, was taken from the deep abyss of this lake. However, it is 
very probable, as Dr, Fisher thinks, that the lake is connected by a submarine 
channel with Rangitoto, which may be the source of the water of the lake. 
