THE ACTIVE VOLCANOES OF NEW ZEALAND 705 



similar to that of Ruapehu. According to all the descriptions 

 given, the lavas are andesites, mostly of the augite-hypersthene 

 type, with small amounts of the hornblende-hypersthene type in 

 some of the earlier flows. The cone consists of alternating lava 

 flows and beds of scoriae. According to Speight 1 the height of the 

 cone was greatly reduced by a terrific explosion, which was followed 

 by extensive lava flows, and which blew 2,000 to 3,000 feet off the 

 mountain. The crater rim now has a maximum altitude of 6,458 

 feet and is made up of a number of peaks surrounding several minor 

 craters. One of these, known as the Red Crater because of the 

 red color of the lava, is situated near the center of the main crater. 

 Another, called Te Mari, lies on the northeast corner, and a third 

 known as Tama is southeast of Ngauruhoe. Tama is believed to 

 be part of the old crater rim, even if it lies beyond Ngauruhoe, and 

 this is proof of the subsidiary character of the latter crater. All 

 these craters are in the solfataric stage, but Te Mari is said by 

 Speight to suffer explosive activity at times and to throw out ashes 

 and stones. It was from this crater that the flow of andesite 

 poured down through the forest on the flank of the mountain, and 

 the conditions indicate that this eruption occurred at a compara- 

 tively recent date, although not within historic time. 



In a depression on the main crater floor there is a small lake, 

 called Blue Lake, lying at an elevation of about 5,500 feet. This 

 lake, Te Mari, Red Crater, and Ngauruhoe all lie in almost a 

 straight line, and they are apparently located on a fissure, or narrow 

 zone of weakness, in the earth's crust. The Ketetahi Hot Springs 

 are situated a little to the east of the line mentioned and well down 

 on the northern flank of the mountain. They exhibit very strong 

 thermal activity. Lying between Ngauruhoe and Ruapehu there 

 are two small lakes, which probably owe their origin to some of the 

 explosive activities of Tongariro. 



MOUNT TARAWERA 



Much has been written on Tarawera but many of the original 

 works are out of print and unavailable. Reports have been 

 prepared for the government bureaus of New Zealand by A. P. W. 



1 Speight, op. cit., p. 11. 



