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volcanic action seems to have made itself a new way nearly at 
every eruption, and has thus splintered into a number of small 
cones, while by always keeping one and the same channel, it 
might perhaps have formed one mighty volcanic mountain. On 
the geological map of the Isthmus I have traced , upon a rectangle 
twenty miles long and twelve miles wide, or within a radius of 
only ten miles from Auckland, not less than 63 separate points of 
eruption. They are volcanoes on the smallest scale , cones of only 
300 to GOO feet above the level of the sea. The Rangitoto , the 
highest among them, rising at the entrance to Auckland Harbour 
as it were the Vesuvius of Waitemata Bay, measures 920 feet. 
Nevertheless, they are perfect models of volcanic cones and craters 
presenting a rich field for observation and ample material for the 
discussion of the question of the formation of volcanic cones and 
craters. A full description with all details I have given in the 
Geology of New Zealand (Scientific Publications of the Novara 
Expedition, Geological Part, Vol. I.); here I may be allowed to 
quote the principal results. 
The volcanic cones of the Isthmus are rising on the basis of 
tertiary sandstone and shale, the horizontal strata of which are laid 
bare in numerous sections on the precipitous bluffs and steep banks 
of the Waitemata and Manukau Harbours. Fossils are an extremely 
rare occurrence in those strata. Only now and then , near the 
water’s edge, thin layers of lignite or drift-wood, changed to brown 
coal, are seen, and on the Nortliside of the entrance to the Orakei 
Bay I discovered glauconitic strata with fossil species of Pecten , 
Nucula , Car (Hum , Turbo , Nerita , and replete with fossil Bryozoes and 
Foraminifera3. These strata were completely broken through by the 
volcanic action from below, and an examination of the points 
of eruption proves , first of all , that volcanic action has repeatedly 
exhibited itself at one and the same place. 
The first outbursts — as a closer examination shows — 
were probably submarine; they took place at the bottom of a 
shallow, muddy bay little exposed to waves and wind, and con- 
sisted of flowing mud mixed with loose masses, such as fragments 
