Lady Knox Geyser- Rachel

Lady Knox Geyser was the second stop we made while visiting the North Island of New Zealand. When we first arrived, we saw what appeared to be a large mound of dirt enclosed by a fence and stadium seating all around it. Excited by the promise of a great show, we all snagged seats as close to the action as possible. Soon a park ranger walked up to the geyser and introduced himself and his bag of soap he brought along for fun. The ranger gave us a brief history of the geyser before beginning the show. Lady Knox Geyser was discovered by a group of prisoners about 100 years ago. These prisoners worked by clearing the trees and shrubs from that area, which obviously left them quite dirty by the end of the day. The prisoners found the geyser and thought it would be a smart idea to bring soap so they could wash themselves in the water from the geyser. Of course, now we know that adding soap to the geyser makes it erupt, which must have been fun to see the first time the prisoners engaged in this activity. After this discovery, the prisoners began building up the cone of the geyser in order to make the eruption higher.
Lady Knox Geyser has a super heated reservoir of water underneath. There are two chambers of water: one contains water of temperature 200°C and the other contains cooler water, which sits on top and acts as a lid. The rocks underneath the geyser act as a heat source for the bottom chamber of water. As the water heats up, pressure continues to build up until the cooler water acting as a lid cannot hold it in any longer. Natural eruptions vary and depend on recent rainfall. They can last for about 45 minutes. Because natural eruptions are so unpredictable, rangers add soap to the geyser every 24 hours for tourists to see it. The soap makes the geyser bubble at first, then it softens the water and mixes the two water chambers to form a flash of steam. The white color of the geyser’s cone is from the silica that precipitates and builds up on the outer surface.
It was a lot of fun to see the geyser erupt and it was interesting to feel the water from the geyser hit your skin. The temperature of the water was a lot cooler than you would expect coming from a chamber of water at 200°C. It was also a great chance for some really fun pictures!

Amanda Bucci's Geopost cards

This is the site of the Tangiwai Railway Disaster located near National Park on the North Island of New Zealand. In 1953 on Christmas Eve, Mount Rupaheu’s crater lake’s natural volcanic ash dam collapsed, causing a mudflow, or a lahar, to plow through everything in its way—including the Whangaehu River, one of the main drainage paths of the mountain. An uninformed train carrying 285 people went over this bridge just minutes after the lahar came through, and as a result, the bridge collapsed into the river. Out of the 285 people on board, 151 died. This is the worst natural disaster to occur in New Zealand’s history. The high viscosity and high density of the lahar has enough momentum to move large boulders, like the ones pictured here. Since this tragic Christmas Eve, the railway company has installed signaling systems to alert conductors about broken rails, and Mt. Rupaheu’s crater lake is being highly monitored for any more dam failures that could cause another deadly lahar.

Pictured here is a moraine next to the Mueller Glacier where we conducted our geology field work on the South Island of New Zealand. In the background is Mount Cook, the highest mountain in New Zealand, and in the right hand corner is a picture of a lichen, which was the focus of our field work. Lichens are the premier pioneering species to grow on a rock after it has been deposited. By measuring the long axis of a lichen, and corresponding the measurement to years on a graph, scientists are able to tell the approximate age of the moraine that the boulder and lichen lies on. When a glacier retreats or advances, it leaves behind large boulder deposits and glacial till that forms a moraine. By dating the moraines, we can tell when the last little ice age occurred in that area. There is usually a 10-20 year lag time from when the glacier deposits the boulder and when the lichens begin to colonize. This means lichenometry data is quite accurate, and simple to obtain. The green part of the lichen is the algae, and the black part is the fungus. The algae fix atmospheric carbon dioxide that the fungi feed off. This symbiotic relationship provides scientists with important data to use in enabling them to date a moraine to determine when the last little ice age was during the late Holocene period.

Torie's Geo Postcards

LADY KNOX GEYSER

On November 17th we visited the Lady Knox Geyser in the Wai-o-tapu geothermal area. Originally the geyser was discovered in 1901 by prisoners who were clearly vegetation in the area to make room for the planting of pine trees. When the geyser was first found it did not have the tall snout on it that you can see in the picture above. The snout was added later as an effort to make the geyser spray higher. The geyser has two chambers of water underneather the ground, one cooler upper chamber and one warmer lower chamber. The upper chamber is cooler because of its proximity to the outside air and never exceeds boiling point and the lower chamber is warmer because of the hot magma underneath it and is about 150 ° C. Naturally the Lady Knox Geyser would erupt every 48-72 hrs but thanks to the help of some park rangers the geyser erupts every morning. Around 10 am the rangers add soap the the throat of the geyser and within minutes the geyser erupts sky high. The reason soap causes an eruption to occur is because it lowers the surface tension of the upper chamber and allows the two chambers to mix together. When the chambers mix together it causes the pressure within the geyser to increase and the only way to release the pressure is to force it up and out the throat of the geyser, causing an eruption! This Geyser is similar to our OLD FAITHFUL in the States!

REVERSED GRADIENT

On our last in New Zealand a colleague if Don Rodbell's, Jamie, came out to Twizel and showed us around the Tasman Glacier and a few outcrops. The out crop above was the second outcrop we looked at and was of a terminal moraine. With in the picture you can see fine well sorted sediment on the bottom of the cross section and bigger, poorly sorted sediment on top. This is known as a reversed gradient or a reverse grading system because normally what we should see is bigger boulder pieces on the bottom and smaller, well sorted sediment on top because heavier boulders fall out of suspension first. The reason this outcrop is different than normal has to do with glaciers. When a glacier does what is known as a glacier leap and bobs above the ground that it is stuck to and allows sediment to pass through the gap between the glacier and the ground. Since the glacier normally only has a small space between the bottom of the glacier and the ground only fine, well sorted material can pass through this gap and then settle out farther down stream. When the glacier gap gets bigger then bigger material is allowed to flow between the gap and thus creates what we see above, a reversed gradient where smaller, more well sorted particles of sediment are at the bottom and bigger, more poorly sorted particles are at the top. This outcrop was my favorite outcrop we looked at beause it truly showed me how sediment cross sections can really tell a story of the history that occured in a particular area!!

Emma's Geopostcards

Crater Lake



White Island is a volcanic island located off the shore of the North Island of New Zealand. On the island, there are a number of crater lakes, including this massive one. It is very colorful, and has white steam coming off of it. This lake is not made up of water that you would find in a typical lake, but is instead hydrochloric and sulfuric acids. The pH of this lake is -0.6, which is much less the pH 2, which is the pH of digestive juices in your stomach. The lake would literally digest you if you were to touch it. The lake fluctuates a lot in both height and temperature. It will randomly drop or rise in level, and is constantly fluctuating about 30 degrees. There is a major fear that if the water level of the lake were to rise to above the crater rim, it would spill out and down to the ocean. This would ruin the marine environment in the harbors and could have serious consequences. The landscape on the island changes so rapidly that it is unclear what the lake and its surroundings will do at any given time.


Mud Pool



This mud pool is located in the Wai-O-Taupo (sacred water) geothermal area, in Rotorua. In this area, geothermal heat is coming up from the Hikurangi Trough, where the Pacific plate is diving under the Australian plate. The mud bubbling causes a funny pooping sound due to concentration of water. It gives off the smell of sulfur, which is similar to rotting eggs. This mud pool phenomenon is caused by magma below the surface, which heats up water. This hot water is less dense, so it rises to the surface and bubbles up through the mud. The mud is made up of volcanic ash and glass. This volcanic material, which has piled up over time, alters to clay with the addition of hot water and shrinks when water is removed from it. This clay is expandable when heat is added and is called smectite. It is sticky and gluey, and can be used as a form of soap, or for facemasks, making it a popular beauty item.

Andrew Scaplen's Geopostcards

The Mudpots of Rotorua (Wai-o-Tapu)

The mudpots are a very hot geothermal area and can reach temperatures around 800º C. The heat comes from the Hikurangi Trough where subduction is occurring. This heats up water underneath the surface of the earth, which rises to the surface over the colder water because the hot water is less dense in comparison to the hot water. This unique geothermal activity produces constant bubbling, but periodic violent eruptions have been known to occur. The hot water from the subduction turns the ash and glass into mud, which bubbles to the surface in order to release the heat. The mud is made from bentenite and smectite, two groups of clay minerals. The glass and ash form clay when they come in contact with the hot water. This expandable matter forms the mud pools when the mud accumulates because the mixture of the glass in the clay and the hot water is unstable. Once the mud cools, it leaves a thin layer of hardened clay at the surface and around the edges of the mudpots. The mud has a greasy feel to it and is used by the cosmetic industry to create mud masks that dry out facial pores, leaving smooth, clear skin. The sulfur emerging from the bubbling mudpots leaves an unpleasant smell similar to rotten eggs. Currently the mud level is particularly low, but the thickness of the mud usually changes with seasonal changes.

Kura Tawhiti Conservation Area

The rocks near Castle Rock are made up of limestone, a sedimentary rock formed by the deposition of sediment layers of calcium and carbon over a long period of time. The rocks were deposited their by glacial movements from the last ice age. We know that they must have come from the last ice age because the soft limestone would not have survived multiple glacial advances. This gives them the age of approximately 12,000 year old (post glacial). The layers of the rocks are chemically weathered, forming a scalloped appearance. There are broken joints where water has percolated into the rock ad corrosion of the inside of the rock has occurred. Rain water seeping into the ground gradually weathered the bedrock forming cracks and joints and once this bedrock became exposed, particularly during the ice age, the freezing water expanded in the cracks and accelerated the weathering process. The ice molded topography also shows evidence of glaciation such as glacial groves and smoothed topography. You can also see signs of glaciation in the rocks from the striations in the soft limestone formed by moving glaciers that have formed abrasions. The repeated freezing and thawing of ice has formed an accumulation of water where constant weathering is occurring cyclically. Some ways to show that this rock is limestone without chemically testing it in the lab is the abundance of fossils which are very common to limestone. Another easy way to tell that this is limestone in the field is that limestone easily dissolves in an acid, so by putting some acidic (low pH) solution on the rock, if the rock fizzes, you know it is limestone.

Travis Blum's Geo Postcards


The Champagne Pool (Wai-o-tapo Geothermal Region)- The remnants of an old explosion crater that have filled with water from a source deep underground. The water is heated underground (up to 230° C) but cools as it rises in the steeply sided crater, creating a sinter (silica) lined pool with colorful deposits of arsenic and antimony sulfur compounds, as well as gold and silver (inset) as the dissolved minerals precipitate out. Named the Champagne pool because of the constant “fizz” on the surface of the pool as carbon dioxide bubbles vent from deep below the water surface inside the pool.


Bergshrund (Mt. Cook, New Zealand Southern Alps. Seen here from the Southeastern Side): A bergshrund is an initial crack in an ice sheet where it breaks away from the underlying bedrock. It is a characteristic feature found on all glaciers, and is an indicator of flow in the body of ice. Several smaller bergshrunds are visible here as horizontal cracks in the thick ice patches near the peak of Mt. Cook, but have not developed into full on glaciers as of yet. More precipitation, or colder temperatures are needed before these smaller ice patches can extend into recognized glaciers.

Fariha Ramay Geology Postcards

Champagne Pool, Wai-O-Tapu Geothermal Area, North Island, NZ



Champagne Pool, approximately 60 m in diameter and 62 m deep, is the largest hot water spring at the Wai-O-Tapu geothermal area in the Waikato region of the North Island of New Zealand. Wai-O-Tapu is located right on the edge of one of the four volcanic calderas within the Taupo Volcanic Zone, one of the world’s most active volcanic areas in the world. Champagne Pool occupies a 700 year old explosion crater formed by a hydrothermal eruption. The pumice material around the pool was also ejected by that eruption. Water enters the pool at about 72°C with a pH of 5.4. The surface temperature of the water in Champagne Pool is 74 °C and bubbles of carbon dioxide can be observed rising to the surface, giving the pool its famous name. As the water flows over the Artist’s Palette towards the Sinter Terraces, the temperatre drops to appromimately 15°C and the pH increases to 7.6. Minerals present in the water of Champagne Pool consist of gold, silver, mercury, sulphur, arsenic, thallium, and antimony which are deposited in the surrounding sinter ledge. The various sinter ledges have been associated with the tilting of the pool as a consequence of earthquake activity.

The orange, green/yellow, and grey colors in the Champagne Pool are the result of antimony oxide, colloidal sulphur/ ferrous iron, and sulphurous mud respectively. The orange-colored edge of the Champagne Pool contains arsenic and antimony sulphur compounds that are rich in minerals including gold and silver. The water overflowing the Champagne Pool is rich in silica, and as the water cools, progressively more silica precipitates and forms into a sinter. The Primrose Terraces have been forming for 700 years and are the largest in the southern hemisphere covering 1.2 ha (approximately 3 acres) since the destruction of the Pink and White Terraces with the eruption of Mt. Tarawera in 1886.




Huku Falls, North Island, NZ






The Huku Falls are natural waterfalls that are located close to Lake Taupo on the North Island of New Zealand and are the result of volcanic activity. Although these falls are not very high, the color of the water is a very unique shade of blue that is the result of very clear water reflecting blue light. The volume of water pasing over the falls varies between 32-270 m3/ sec. At the base of the falls is a dangerous undertow caused by the falling water plunging deep into the pool. Water temperature varies from 22°C in the summer to 10.5°C in the winter. The average daily flows over Huka Falls is 160 m3/ sec. The Waikato River (100 m wide and 4 m deep) is forced into a channel 15 m wide and 10 m deep upstream. The level of the River is controlled by Lake Taupo’s control gate bridge.

The pounding of water at the base of the waterfall is a powerful force for erosion. Even at the lip of the waterfall, the water gains extra erosive power as it accelerates when approaching the brink. Therefore, waterfalls are ephemeral phenomena, geologically speaking. While the surging water tears away at the base of the falls and removes its rock foundations, the scouring of the lip grinds back the brink of the falls and decreases its overall height. In geologic terms, waterfalls are quite temporary, and their presence is a sign of the unique geologic conditions that produced them.

Creation of Huku Falls:

An ancient lake once covered most of what is today the Waikato River Valley. Eventually, the lake drained and the Waikato River eroded through soft mudstone and pumice until it struck a layer hardened by silica from much earlier geothermal activity. Unable to erode this later, the river became confined to joints and fissures in the rock. Over the centuries, the river cut a deep narrow channel into this hard layer until it reached a soft underlying layer which collapses, creating the steep-side basin and the falls where the river plunges over the lip into the basin. Today the river continues this erosion process and the Huku Falls move upstream.

Rivers begin re-grading their courses and establishing a new curve of water erosion. Where the latter curve meets the former curve, there is a break in the slope of the river, called the knick point. The knick point usually forms a fall line over which descend the tributaries to the main stream.

The Waikato River System is the most highly developed for electicity generation in New Zealand. It supplies 8 hydroelectic stations and provides cooling water for 2 geothermal and 1 thermal stations. The 11 stations on Waikato produce 65% of the North Island/s power generation and approximately 25% of New Zealand’s hydropower, which constitutes 15% of New Zealand’s total power.