396 COSMOS. 



the quart zose rocks formerly called primeval. Dana has like- 

 wise collected them on the northern island of New Zealand, 

 to the west of Tipuna, in the Bay of Islands. 94 



New Holland exhibits only on its southern extremity 

 (Australia Felix), at the foot and to the south of the Gram- 

 pian Mountains, fresh traces of former igneous action, for 

 we learn from Dana that a number of volcanic cones and de- 

 posits of lava are found to the north-west of Port Phillip, 

 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, Carteret and La Billardiere, in a 

 state of ignition and throwing out lava. 



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

 north-eastern 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 ex- 

 ample is the case in a very limited area near the Bay of Islands 

 (lat. 35 2'), where the ash-cones, crowned with extinct craters, 

 Turoto and Poerua rise ; and again, more to the south-east, 

 (between 37-^- and 39^- lat.), where the volcanic floor runs 

 quite across the centre of the north island, a distance of more 

 than 160 geographical miles from north-east to south-west, 

 from the Bay of Plenty on the east to Cape Egmont on the 

 west. This zone of volcanic action here traverses, (as we 

 have already seen it to do on a much larger scale in the Mexi- 

 can Continent) in a diagonal fissure from north-east to south- 

 west, 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 Ton- 

 gariro* (6198 feet), whose crater is found on the top of the 

 ash-cone, Bidwill, and, somewhat more to the south, Ruapahu 



94 See Dana, ibid. p. 438 446, and on the fresh traces of ancient vol- 

 canic action in New Holland, pp. 453 and 457 ; also on the many basal- 

 tic columns in New South Wales and Van Diemen's Land, p. 495 510 ; 

 and E. de Strzelecki, Phys. Descr. of New South Wales, p. 112. 



