VOLCANIC
SPRINGS

Orakei Korako - page 2

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Behind Map of Africa the Rainbow Terrace continues in northeastern direction and hosts several further springs, most of them hard to spot. Seen from the trail, which is aligned parallel to the terrace, often only steam plumes and colourful deposits along runoffs or steam outlets indicate their positions. Two examples are shown on the next photos.

Spring on Rainbow Terrace
Spring with thermally coloured rockface on Rainbow Terrace

The second example sits just beyond Map of Africa.

Rainbow Terrace
Wall segment above a spring at Rainbow Terrace, tinted by geothermal activity

Next to the trail two small springs are recessed in the sinter wall and attract attention for the most part by their colourful runoff channels. The spring on the lefthand side is called Tim and Terry Geyser, and it formed the sinter curtain that hides it from view by splashing water. Due to the hidden position eruption heights and intervals are quite hard to determine. The name refers to Tim Boddy and Terry Spitz, the former owners of Orakei Korako tourist business. A description of Tim and Terry Geyser from the point of sinter formation is given by B.W. Mountain et al.; Experimental studies on New Zealand hot spring sinters: rates of growth and textural development, Can. J. Earth Sci. 40,1643–1667, 2003.

Tim and Terry Geyser
Tim and Terry Geyser, inside the small cave on the lefthand side

A small cave entrance and outlet of a hidden spring, leading almost at eye level into the scarp, gave Devil's Throad its name.

Devil's Throad on Rainbow Terrace
Position of Devil's Throad on Rainbow Terrace, Tim and Terry Geyser in background

This small spring usually acts as a perpetual spouter, but geyser-like activity up to 0.8 m (2.6 feet) height was seen in 2004.

Devil's Throad
Devil's Throad

While Devil's Throad is the last noteworthy feature at the northern edge of the Rainbow Fault Scarp, there is a prominent pool in the southern section of the fault, which can be reached on a separate trail. You have to turn right on this trail even before (west of) Diamond Geyser, and after a somewhat steeper ascent you meet a blue pool on the righthand side. This ancient hot spring carries the names Waiariki (Waters of the Chief), Soda Fountain and My Lady's Lace. Usually, Soda Fountain shows more or less strong upwelling, interrupted by times of complete dryness, but from 1984 to 1996 rarely true geyser activity with eruptions up to 1 m (3 feet) height were observed. Before 1984 Soda Fountain was empty for 17 years. The Rainbow Fault, which activates this pool, then continues in southwestern direction to Kurapai Geyser and beyond.

Soda Fountain
Waiariki, Soda Fountain or My Lady's Lace

Let's go back to Devil's Troad to resume the walk along the main trail. North of Devil's Throad the trail forks - to the left (west) towards a small crater blasted out by an hydrothermal eruption in January 2001, and to the right around a curve towards the higher located Golden Fleece Terrace. This is an old terrace, generated in 131 AD by the same volcanic and seismic events as the other terraces at Orakei Korako. Laying dry for a long time, in 2001 the formation was revitalised by draining waters from Artists Palette, which led to the renewed growth of yellow-brown thermophilic bacteria and finally rejustified the place name.

Golden Fleece Terrace
Golden Fleece Terrace with Cauldron Geyser in foreground

The Māori name for this 40 m (130 feet) long and 5 m (16.5 feet) high terrace is Te Kapua (The Cloud). Along the trail the northernmost notable feature on this level is called Fred and Maggie Pool. Neither could I find out who Fred and Maggie were, nor which side of the double pool refers to Fred and wich one to Maggie. The activity of this feature varies between overflow and boiling, both can be steady or oscillating.

Fred and Maggie Pool
Fred and Maggie Pool

Before 2004, the southwest end of the exposed section of Golden Fleece Fault Scarp was a hot spot of geyser activity. It was found that it depended closely on the amount of rain and thus on the groundwater level. Some of the former geysers are still visible, others are more or less completely obliterated.
According to the 1972 Lloyd map, the feature closest to the south end of the trail running in parallel to Golden Fleece Fault Scarp is called Manganese Pool. On location since decades the name sign "Wairiri Geyser" is placed immediately in front of the pool and leads to a confusion between the two features. Even the Geothermal Features Annual Monitoring Reports, prepared by experts for the Waikato Regional Council, treated the pool as Wairiri Geyser. Eventually, this mix-up has been corrected to "Manganese Pool" in the new Waikato Regional Council Technical Report 2020/04, Sinter-forming springs and geysers of the Waikato region. Now only the sign needs to be replaced. Manganese Pool used to be a quiet, sometimes overflowing blue spring close to boiling temperature until 2009, then it cooled down to temperatures between 50 and 80 °C (122-176 °F).

Manganese Pool
Manganese Pool

In a pronounced form Manganese Pool currently exhibits the growth of deep yellow Conophyton stromatolites, built by filamentous cyanobacteria such as Phormidium tenue var. granuliferum. Similar stromatolithe cones are already known from the Precambrian period, more than 540 million years ago, so these structures are a kind of living fossils.

Beyond Manganese Pool, near the base of Golden Fleece Fault Scarp, the somewhat larger, oval pool of Cauldron Geyser, also called The Cauldron, shows up. This 2 m (6.5 feet) high playing geyser is dormant since the late 1940s.

Cauldron Geyser
Cauldron Geyser

To the right and lefthand sides of Cauldron Geyser several additional geysers were active in the past. Most prominent among them were Petrifying Pool, Scarp Geyser and Prince of Wales Feathers Geyser northeast of Cauldron and Dreadnought Geyser and Wairiri Geyser in the southwest. The location of Prince of Wales Feathers Geyser just at the base of the scarp is still quite easy to spot. It played up to 3 m (10 feet) high at intervals sometimes as short as every few minutes. Eruptions were last seen in 2003, their height was around 0.7 m (2 feet).

Dreadnought Geyser too, was probably for the last time active in 2003. Its eruptions reached heights of 10 metres (33 feet). The small pool of Dreadnought, about one metre in diameter, appears inside the grotto just at the foot of the thermal cascade down the scarp. Close by is Wairiri Geyser (Furious Water), which occupies the southernmost edge of Golden Fleece Fault Scarp just below the trail. However, due to the dense vegetation it is almost impossible to spot from the trail next to it above Golden Fleece Terrace, whereas the trail close to Mangenese Pool offers still a limited view. The geyser was firstly observed in December 1961, when it erupted up to 3 m (10 feet) high at an interval of 10 minutes. In 1983 eruption heights of 5-6 m (16-20 feet) were seen (R.G. Allis, Proceedings 5th NZ Geothermal Workshop 1985), and A.D. Cody even stated 10 m. Unfortunately, Wairiri Geyser played for the last time in March 2003.

Dreadnought Geyser
Dreadnought Geyser inside a grotto at the foot of the thermal waterfall. The circular blue pool in the lower right corner of the picture probably is Wairiri Geyser. Cauldron Geyser occupies the lower left corner.

The trail continues uphill to the top of Golden Fleece Terrace and farther to Elephant Rock on the righthand side. Elephant Rock is not only an old sinter formation in the amazingly accurate shape of an elephant's head and shoulder, but moreover an active fumarole.

Elephant Rock
Elephant Rock

Shortly afterwards the first of three viewpoints of Artist's Palette or Kei Runga ite Mānia (Open Plain on the Top) is reached. This is the topmost sinter terrace of Orakei Korako and with more than 10,000 m2 also the most extended. The sinter on Artist's Palette fills an old hydrothermal eruption crater that formed between 8,000-14,000 years ago. Because the first viewpoint does not provide a complete overlook, I begin with a photo taken from the highest available viewpoint.

Artist's Palette
Artist's Palette, panoramic view with Lake Ohakuri in background

Artist's Palette is not always that colourful, but at irregular intervals the thermal water recedes and leaves large sections of the plain dry and greyish-white. When the water level is high, microbe communities in various shades of yellow, orange and brown colonise the runoff areas of the hot springs. The light or deep blue water of the hot springs not only makes a stunning contrast, but also points to the chemistry of the hydrothermal system. Its alkali chloride fluids are rich in dissolved silica, thereby supporting both the microbial life and the abundant formation of white siliceous sinter.

The western section of Artist's Palette is dominated by large blue pools. On the lefthand (west) side of the next photo the two largest, partially merging blue pools of the cluster are listed as springs 773 and 774, better known as Twin Pools, while the extended blue pool on the righthand side carries the name Artist's Palette Pool or simply Palette Pool. Just outside of the picture frame on the lefthand side a geyser named Psyche’s Bath (Rock and Roll Geyser was a second name) is located, which played up to 18 m (59 feet) height in 1957. Thereafter eruptions only reached 3-5 m (10-16 feet). Although sitting almost next to the trail, now the crater of Psyche’s Bath is hard to spot because bushes obscure the view.

Artist's Palette
Artist's Palette with Twin Pools on the lefthand and Palette Pool on the righthand side

Palette Pool is a geyser and erupted approximately 18 m (59 feet) high in July and August 1995. But even if weaker geyser activity from this feature and the vent S1012 on the near side within the pool was already seen before, it nevertheless remains a very rare spectacle. The inconspicuous little hole within the brown coloured sinter area on the righthand side of the next photo is spring 792, which erupted in November 2010 up to 5 m (16 feet) high.

Artist's Palette Pool
Palette Pool, also encompassing vent 1012 on the near side

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