TRUE VOLCANOES. 371 



lava are found to the northwest of Port Philip, as also in 

 the direction of the Murray River (Dana, p. 453). 



On New Britain* there are at least three cones on the 

 west coast, which have been observed within the historical 

 era, by Tasman, Dampier, Cartaret, and La Billardiere, in a 

 state of ignition and throwing out lava. 



There are two active volcanoes in New Guinea,* on the 

 northeastern coast, opposite New Britain and the Admiralty 

 Islands, which abound in obsidian. 



In New Zealand, of which the geology of the north island 

 at least has been illustrated by the important work of Ernst 

 DiefFenbach, and the admirable investigations* of Dana, ba- 

 saltic and trachytic rocks at various points break through 

 the generally diffused Plutonic and sedimentary rocks. This 

 example is the case in a very limited area near the Bay of 

 Islands (lat. 35° 2''), where the ash-cones, crowded with dis- 

 tinct craters, Turoto and Poerua rise; and again, more to 

 the southeast (between 37^° and 39i° lat.), where the vol- 

 canic floor runs quite across the centre of the north island, a 

 distance of more than 160 geographical miles from northeast 

 to southwest, from the Bay of Plenty, on the east, to Cape 

 Egmont, on the west. This zone of volcanic action liere 

 traverses (as we have already seen it to do on a much larger 

 scale in the Mexican Continent), in a diagonal fissure from 

 northeast to southwest, the interior chain of mountains which 

 runs lengthwise in a north and south direction, and which 

 seems to give its form to the whole island. On the ridge of 

 this chain stand, as it were, at the points of intersection, the 

 lofty cone of Tongariro^^ (6198), whose crater is found on 

 the top of the ash-cone, Bidwill, and, somewhat more to the 

 south, Ruapahu (9006 feet). The northeast end of the zone 

 is formed in the Bay of Plenty (lat. 38^) by a constantly 

 smoking solfatara, the island volcano of Puhia-i-wakati(*)* 

 (White Island). Next follow to the southwest, on the shore 

 itself, the extinct volcano of Putawaki (Mount Edgecombe), 

 8838 feet high, probably the highest snowy mountain on New 

 Zealand ; and in the interior, between Mount Edgecombe and 

 the still burning Tongariro,* which has poured forth some 

 streams of lava, a lengthened chain of lakes, partly consist- 

 ing of boiling water. The lake of Taupo, which is surround- 



(*) Ernst Dieffenbach, Travels in New Zealand, 1843, vol. i., p. 337, 

 355, and 401. DiefFenbach calls White Island "a smoking solfatara, 

 but still in volcanic activity" (p. 358 and 407), and on the chart, " in 

 continual ignition." 



