512 J. Malcolm Maclaren — The Waters of Geysers. 



or ig7ieogenou8 ; the geyser waters of Iceland, New Zealand, and 

 the Yellowstone regions are probably mainly of this character, as 

 maintained by Suess) ; these primitive hot vapors and waters rise 

 and penetrate the zone of circulating meteoric waters, heating the 

 latter and charging them with both metallic salts and with fluorine, 

 chlorine, bromine, and other mineralizing agents." 



Recent geyser phenomena in New Zealand have led me to doubt 

 more than ever the validity of this inference of Suess. New 

 Zealand contains one of the most active of fumarolic areas, and, 

 curiously enough, the life-history of its greatest geyser — the greatest 

 also that the world has yet known — is strikingly illuminative of 

 the subject under discussion. For confirmatoi'y details of the history 

 of this geyser I am indebted to the courtesy of Mr. Colin Fraser, of 

 the New Zealand Geological Survey. Waimaugu Geyser was 

 discovered in January, 1900, but it had doubtless been in existence 

 for a short time prior to that date. Its basin was then some 130 

 feet long and 80 feet wide, at ordinary times full of black muddy 

 water. Although it played almost daily, its eruptions were most 

 irregular in character, sometimes expending their energy in a single 

 outburst, hurling a mass of water estimated at 800 tons to 

 a maximum height of 1,500 feet, at other times playing lightly and 

 intermittently for five to six hours. The intervals between 

 eruptions were rarely more than 30 hours. For more than four 

 yenrs after its discovery Waimangu was in active eruption, but 

 during July and August, 1904, it remained quiescent for nearly two 

 months. After this period of inactivity it recommenced its eruptions 

 with unabated and indeed often increased energy, and so continued 

 until 31st October, 1904, when, with the exception of a feeble 

 eruption on the following day, it ceased spouting, and now remains 

 doimant or is extinct — a flowing pool with a temperature of 130° F. 



The modern history of Tarawera Lake, four miles to the north- 

 east of Waimangu, is important in this connection. The explosive 

 eruption of Tarawera Mountain in June, 1886, threw a great ash 

 barrier across the valley which formed the natural outlet for the 

 waters of Lake Tarawera. (For a graphic description of this 

 Tarawera rift area, vide Geog. Journ., April, 1906.) The level of 

 the lake at once rose some 28 feet, and after some time, as the 

 outlets through the ash barrier became choked with debris, continued 

 to rise still further. By the end of October, 1904, the waters had 

 risen another 14 feet. At that height and on the 1st November, the 

 do;/ on which Waimangu last played, the waters overtopped the 

 barrier. On the following day the level of the lake had fallen three 

 feet, and on the 3rd November the barrier was carried away. The 

 waters of the lake rushed over the Tetauahape escarpment and 

 escaped by an old channel at the rate of more than a million and 

 a halt cubic feet per minute, forming, for the few days they lasted, 

 a stupendous cataract. The level of the lake is now eleven feet 

 below the maximum height of 1904, and its waters now escape by 

 the normal subterranean channels, which from Maori legends are 

 known to have been in existence for centuries. 



