Old Geyser

We concluded our Wai-O-Tapu tour with a visit to the Lady Knox Geyser, christened so not by the person who discovered it, but by someone visiting it some time afterward. It has a more interesting story to its discovery, as the area in question was originally a prison camp. Some of the prisoners stumbled upon a hot spring and had the bright idea that they wouldn't need to drag their clothes long distances or boil the water to get the laundry done. Now at the time, there was no funnel, no real indication that there was any issue with this source of water, but the warm layer that they were to wash in was sitting above an underground layer of super heated water, building pressure below the cooler layer. After beginning to wash their clothes with some soap, they were surprised by a sudden gushing of water which eventually led to their frantic dash from the pool and the scattering of their clothing downstream of the springs after being launched high into the air. The soap had reduced the surface tension of the cooler spring waters which allowed the pressure from the super heated layer below to come explosively through.

This was the story our wonderful guide layed out for us, although mine is a condensed version. Eventually, the prisoners set the geyser off as entertainment, building up a cone to project the energy into a more focused blast. The super heated water contains dissolved silica, which was deposited all over the area  to create the mound in the picture. The guide jokingly clarified that "what we were looking at is a geyser", as he pointed to it, "not a geezer" as he gestured to himself. 

He then dropped in a packet of biodegradable soap and slowly wandered off. After a few minutes the water began to bubble out of the mouth of the geyser before it violently but rather abruptly shot to 25 metres in a rain of silica-rich, super heated water, accompanied by vast amounts of steam in the chilly air.

Finding out this geyser was manipulated by man rather than a natural eruption was a bit disappointing , however it was a magnificent example of how a little knowledge can be used in wonderful ways, as this was frankly by far the most impressive science experiment I have ever seen.