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In 1867 the German-Austrian geologist Ferdinand von Hochstetter wrote: "[The Taupō Volcanic Zone is a] wonderful zone of hot springs, which by far exceeds all others in the world in variety and extent ... " (F. von Hochstetter; New Zealand, its physical geography, geology and natural history, J.G. Cotta, 1867). His enthusiastic praise is understandable against the backdrop that this zone hosted at Hochstetter's time, among other spectacular hot springs, more world-class geysers than any other spot on earth except the somewhat later disclosed Yellowstone. Knowing this, you may feel the bitter irony about the fact that nowadays one of the three most famous active geysers of New Zealand is an artificial one. The renown of Lady Knox Geyser, on the other hand, may also be attributed to an excellent marketing by the Waiotapu business owners.
The show starts every day at 10:15 a.m. in an amphitheatre-like setting. Visitors who want to see Lady Knox Geyser in action have to leave the main Waiotapu (Sacred Waters) tourist area for a 1.3 km (0.8 mi) walk or drive to the fenced geyser site in the northeast. Outside of the show time the site is closed. The geyser is named after Lady Constance Knox, daughter of Uchter Knox, 5th Earl of Ranfurly and Governor of New Zealand from 1897 to 1904. This would not mean that Constance Knox had something to do with the discovery of the underlying hot spring, the idea to turn it into a geyser, or the construction of the geyser mound on top of the spring. Allegedly, it was typical British humor about the unusual fact that this lady was a heavy smoker to name the geyser for her, after her father had visited the nearby Waiotapu prison in May 1903. The story goes that two years earlier a gang of prisoners discovered both the spring and the possibility to make it erupt by adding soap. Probably, they also were the workers when it came in 1906 under the direction of the chief wardener of the prison to the insertion of a cast iron pipe and the formation of the artificial geyser mound from pumice blocks. Over the decades sinter coated the structure and gave it a near natural appearance. Since the covered hot spring is no natural geyser, still today an environmentally friendly surfactant must be added to trigger the eruption. Accordingly, when Lady Knox Geyser starts about 4 minutes later it first looks more like an effervescing champagne bottle rather than a natural geyser setting in.
Within one minute after the initial ejection of lather the eruption column slowly gains altitude until the maximum height of 10 to 20 m (33-66 feet) is reached. Then Lady Knox Geyser may continue playing up to an hour. But under less favourable conditions the play can already terminate after some minutes.
Besides Lady Knox Geyser the Wai-O-Tapu Thermal Wonderland, as the site 30 km (19 miles) southeast of Rotorua is effectively labeled nowadays, has much more to offer. Arguably most famous is the Champagne Pool with its bright orange rim, but also the neon green Roto Kārikitea (Devil's Cave) is quite popular. Less well known are the five natural geysers in the area. Their wallflower role is understandable because they are small to medium sized ones, not very reliable, and only three of them are accessible to tourists.
Starting at the visitor centre the trail crosses Waiotapu Stream on a bridge. Looking upstream in direction of Lady Knox Geyser, which lies next to the stream but cannot be seen from the bridge, the abundant steam of a hot spring catches the eye. The spring itself remains obscured from this viewpoint, though.
Following the loop trail in the officially recommended, southeasterly direction for about 400 m opens a view at The Weather Pool on the bottom of a deep gully. It was shown in the old tour pamphlet, but the current one does not mention this spring. Edward F. Lloyd apparently designated The Weather Pool or a spring nearby as N85/6/59 in his New Zealand Journal of Geology and Geophysics article The hot springs and hydrothermal eruptions of Waiotapu from 1959, which is a kind of scientific standard work about Waiotapu. He suggested that the high flow of near boiling water from N85/6/59 may represent the combined discharge of all the craters on location which otherwise lack any surface runoff.
The non-consideration of The Weather Pool is not the only difference between the old and the new tour pamphlet. In the new one, issued after the business had been bought in 2012 by the local Arawa tribe, most of the English names are either replaced by the original Māori names or translated into Māori language. This does not only put things straight from the historical perspective but many of the English names were neither intentive nor unique. Some even reflected the antiquated but widely spread belief that volcanic features are of the devil. However, for the sake of completeness and since they are now part of the history I have added them in the image captions.
The first of three subsequent loop trails, which give access to the tourist area, leads visitors clockwise along 7 of more than 20 large craters which perforate the dangerous ground of this section. These are mainly collapse features induced by erosion processes. Steam and volcanic gases such as carbon dioxide, sulfur dioxide, and hydrogen sulfide arise from reservoirs in the deep and form acidic compounds which decompose the volcanic rock. Thus, large cavities develop underground and when a roof section collapses a crater opens up. Walking the loop trail clockwise, the Māhanga Rua (Twin Craters) are the first ones you come across.
The slightly larger second crater is to be found 20 m (66 feet) to the east.
Māhanga Rua is followed to the southeast by Te Rua Uenuku (The Crater of Uenuku). In Māori mythology, Uenuku is the god of rainbows, and accordingly the English name was Rainbow Crater. Obviously, Te Rua Uenuku is not always calm because Bridget Y. Lynne reported an eruption of hot mud to a height of approximately 8 m (26 feet) on 29th January 2001 (B.Y. Lynne; Monitoring of Geothermal Features, Environment Waikato Technical Report 2009/25).
Even larger and heavier steaming is Te Rua Whaitiri (The Crater of Thunder), the next pit along the trail. Two descriptive boards in the area refer to the crater, one at the start of the trail and the other one directly in front of Te Rua Whaitiri. They constitute a kind of mystery because one dates the formation of the crater back to the year 1967, the other one to 1968. Either way, the description on location says that the collapse of the roof sounded like rolling thunder which gave rise to the name of the pit.
West of Te Rua Whaitiri the sequence of more or less empty craters is interrupted by some mud pools, but it will continue when the loop trail leads back to the visitor centre. These mud pools are called Ipu (Bowl) and contain a viscous slurry of hot, dark reddish-brown mud, coloured by graphite, iron oxides and crude oil. Occasionally, some rising bubbles paint a pattern of lighter circles on the surface.
To the east three further, albeit smaller Ipu mud pots follow.
Subsequently the trail curves around a fifth mud pot, which is neither mentioned in the tour pamphlet nor signposted on location. It may or may not be part of the Ipu mud pots.
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