TIIE GEOLOGY OP AUCKLAND. 
27 
The first volcanic eruptions were submarine , consisting of vast 
quantities of trachytic lava, breccia, tuff, obsidian, and pumice- 
stone, which flowing over the bottom of the sea, formed an 
extensive submarine volcanic plateau. The volcanic action 
continuing, the whole mass was upheaved above the level of the 
sea, and new phenomena were developed. The eruptions going 
on in the air instead of under the sea, lofty cones of trachytic 
and phonolithic lava, of ashes and cinders, were gradually formed. 
These eruptions, breaking through the original submarine layers 
of trachytic lava, breccia, and tuff, raised them, and left them, 
as we now find them, forming a more or less regular belt 
round the central cones, and having a slight inclination from the 
centre outwards. These belts I shall have occasion to refer to 
tinder the name of “ tuff-craters or “ cones of tuffs” or “ craters 
of elevation ” In the course of time the volcanic action 
decreased, and we must now imagine that tremendous earth¬ 
quakes occurred—that parts of the newly formed crust gave way 
and fell in, forming vast chasms and fissures, which are now 
occupied by the lakes, hot springs, and solfataras. 
Thus we now find in the central part of the Northern Island 
an extensive volcanic plateau of an elevation of 2,000 feet, from 
which rise two gigantic mountains, Tongariro and Ruapahu . 
They are surrounded by many smaller cones, as Pihanga, 
Kakaramea, Kaharua, Rangitukua, Puke Onake, Hauhanga. 
The natives have well named these latter, “ the wives and 
children of the two giants Tongariro and Ruapahu ; ;; and they 
have a legend to the effect, that a third giant, named Taranaki , 
formerly stood near these two—but quarrelling with his com¬ 
panions about their wives, was worsted in combat, and forced 
to fly to the West Coast, where he now stands in solitary 
grandeur, the magnificent snow-capped beacon of Mount 
Egmont (8,270). These are the three principal trachytic cones 
of the Northern Island. 
By far the grandest and loftiest of the, three is Ruapahu , 
whose truncated cone, standing on a basis of about 25 miles in 
diameter, attains a height of 9,000 to 10,000 feet above the level 
of the sea—about 3,000 feet of which is covered with glaciers 
and perpetual snow. Ruapahu, like Taranaki, is extinct. 
Tongariro alone can be said to be active. I was enabled to 
