J. Malcolm Maclaren — The Waters of Geysers. 513 



In Waimangn Geyser itself there has been no recrudescence since 

 the breaking away of Lake Tarawera, and in tlie immediate vicinity 

 there has been one outburst only. This took place on 21st February, 

 1906, at Frying Pan Flat, but lasted only a few hours. Frying Pan 

 Flat is, however, an old geyser crater that had been in eruption 

 during the period of Waimangu activity. Thermal relief along the 

 Tarawera rift is now effected by comparatively mild eruptions, the 

 character of which would seem to indicate expulsion from slowly 

 filling subterranean reservoirs. 



Other large geysers in the New Zealand area show or have shown 

 a degree of dependence on superficial waters. Dr. Wohlmann, 

 Government Balneologist, instances the case of the Crow's Nest Geyser 

 at Taupo, on the banks of the Waikato River, near its emergence 

 from Lake Taupo. "When the Waikato River is in flood the Crow's 

 Nest Geyser plays every 40 minutes. With low waters the interval 

 is increased to two hours. At Orakeikorako, some fifteen miles to 

 the north and also on the banks of the Waikato River, the great 

 geysers last played when the Waikato River was abnormally high. 

 Thermal manifestation at Orakeikorako has since been confined to 

 hot springs. 



Every gradation from Waimangu through boiling springs to 

 faintly bubbling warm pools are known in the New Zealand area, 

 and it seems impossible to make any genetic distinction between the 

 most active and the more lethargic members of the series. Yet 

 some of the latter are obviously dependent for their waters on surface 

 supplies. The heat necessary to create the motive force of these 

 geysers lies certainly at no great depth. For many years after the 

 1886 eruption it was possible to char wood by plunging it into 

 a crevice in the ash beds. While, therefore, the heat supplied to 

 the geysers may certainly be considered magmatic, it is nevertheless 

 directly applied, and is not carried to the geyser tube by magmatic 

 waters and vapours such as have been called into existence in the 

 passage quoted in the first paragraph of this communication. 



Nor even in this New Zealand region, the evidence from which 

 points to the meteoric origin of geysers and hot springs, is the 

 evidence of contemporaneous metallic deposition lacking. By the 

 courtesy of the New Zealand Geological Survey I am enabled to 

 publish two interesting analyses, or rather assays, made by the 

 Colonial Analyst, of fumarolic deposits from Whakarewarewa, 

 immediately south of Rotorua. Siliceous sinter taken from the 

 sides of a trough used to conduct hot water from a large pool behind 

 the Geyser Hotel gave — 



d\vts. grs. 



Gold 12 per ton. 



Silver 15 3 ,, ,, 



while a sulphurous sinter formed on the edge of the spring showed : — 



ozs.dwts.grs. 



Gold 14 per ton. 



Silver 4 18 „ ,, 



both most suggestive results. 



DECADE T. VOL. III. NO. XI. 33 



