Wednesday, October 27, 2010

October 1. West Yellowstone. Mammoth Hot Springs.

Our first destination was Mammoth Hot Springs.
Here's what we saw from the car from a distance.
There's a small village near the Hot Springs and here's the hotel. The hanging baskets of petunias were lovely. Note to self: Self, do more hanging baskets next spring.
Hydrothermal features are fragile rarities of nature and Yellowstone Park preserves the largest collection of hydrothermal features on the planet. Changes take place naturally in a hydrothermal area but people can disrupt these processes and cause irreparable damage by throwing sticks, rocks, or other objects into these areas. Such objects can become permanently cemented into place, choking off water circulation and ending all activity.
The ground here is highly unstable and the water is scalding. My kind of place.
This is Liberty Cap. A dormant hot spring cone. Thirty-seven feet high, this cone was created by a hot spring that was active in one location for a long time. The internal pressure was sufficient to raise the water to a great height, allowing mineral deposits to build slowly and continuously for possibly hundreds of years.
In thermal areas, the ground may be only a thin crust above boiling hot springs or scalding mud. There is no way to guess a safe path: new hazards can bubble up overnight, and some pools are acidic enough to burn through boots. More than a dozen people have been scalded to death and hundreds badly burned and scarred. Leaving the boardwalk or trail, or taking pets beyond this point, is unlawful and potentially fatal. Throwing objects into thermal features, collecting specimens, or defacing formations destroys what nature took centuries to build. Violators will be prosecuted. Well, you know Rosie is one freakin' happy camper what with being just inches away from a certain, scalding death.
Oh, the risks I take for my readers. You just have no idea.
What is a hot spring? A hot spring is a spring (namely any natural occurrence where water flows to the surface of the earth from below the surface) produced by the emergence of geothermally heated groundwater from the earth's crust. If water percolates deeply enough into the crust, it will be heated as it comes into contact with hot rocks. The water from hot springs in non-volcanic areas is heated in this manner. Since we are in a VOLCANIC AREA, water is heated by coming into contact with magma or molten rock. In general, the temperature of rocks increases with depth. The rate of temperature increase with depth is known as the geothermal gradient. The high temperature gradient near magma may cause water to be heated enough that it boils. If water becomes so hot that it builds steam pressure and erupts in a jet above the surface of the earth, it is called a geyser. (And yes, I have pictures and videos of Old Faithful coming up.) If water only reaches the surface in the form of steam, it's called a fumarole. If the water is mixed with mud and clay, it's called a mudpot. Hot springs in volcanic areas are often at or near boiling point
In Mammoth Hot Springs, limestone is the dominant underlying rock here instead of rhyolite, which is dominant in the park's other major hydrothermal areas. Rhyolite is an acidic, very fine-grained igneous rock rich in silica content, the volcanic equivalent of granite. Limestone is a sedimentary rock consisting mainly of calcium that was deposited by the remains of marine animals. In case you need a basic geology lesson in rocks, here it is: There are three basic types of rocks (a rock being a mass of hard consolidated aggregate of mineral matter)- igneous, sedimentary, and metamorphic. Igneous rocks are crystalline solids formed directly from the cooling of magma. It's an exothermic process (It loses heat.) and involves a phase change from the liquid to the solid state. Igneous rocks are named according to two things: composition or what they're made of, and texture or how big the crystals are. Examples of igneous rocks are granite, basalt, obsidian, and pumice. Sedimentary rocks are formed by sedimentation of material at the earth's surface and within bodies of water. Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are contained and to come to rest against a barrier. In geology, sedimentation would be the polar opposite of erosion. It describes the process of the deposition of sediment which results in the formation of sedimentary rock. Sedimentation is the collective name for the processes that cause mineral and/or organic particles or detritus to settle and accumulate or minerals to precipitate from a solution. The sedimentary rock cover of the continents of the earth's crust is extensive, but estimated to be only about 5% of the total volume of the crust. Sedimentary rocks are a thin veneer over a crust consisting mainly of igneous and metamorphic rocks. Sedimentary rocks are deposited in layers as strata, with each stratum having internally consistent characteristics that distinguish it from other layers. Each layer is generally one of a number of parallel layers that lie one upon another, laid down by natural forces. Strata are typically seen as bands of different colored or differently structured material exposed in cliffs, river banks, quarries, and road cuts. Each band represents a specific mode of deposition- river silt, beach sand, sand dune, coal swamp, lava bed, etc. In most places on the surface of the earth, the igneous rocks which make up the majority of the crust are covered by a thin veneer of loose sediment. Sedimentary rock is made as layers of this debris get compacted and cemented together. There are three basic types of sedimentary rock: Clastic - accumulations of clasts (grains of sediment, silt, sand, gravel, etc.), little pieces of rock which have piled up and been lithified by compaction and cementation. Lithification is the process in which sediments compact under pressure, expel fluids, and gradually become solid rock. Chemical - formed when standing water evaporates, leaving dissolved minerals behind. These are very common in arid lands with playa lakes, or dry lakes. Dry lakes are an ephemeral lakebed - a flat consisting of fine-grained sediments infused with alkali salts. Thick deposits of salt and gypsum can form due to repeated flooding and evaporation over long periods of time. Organic - any accumulation of sedimentary debris caused by organic processes. The calcium used by animals - shells, bone, and teeth - can pile up on the seafloor and accumulate into organic sedimentary rock. Types of sedimentary rocks include coal, iron ore, limestone, rock salt, sandstone, siltstone, and shale. Metamorphic rocks get their name from "meta," or change, and "morph," or form. Any type of rock can become a metamorphic rock. All that is needed is for the rock to be in an environment in which the minerals which make up the rock become unstable and out of equilibrium with their new environmental conditions. Usually this requires burial, which leads to an increase in both temperature and pressure. The metamorphic changes in the minerals always move in a direction designed to restore equilibrium. Common types of metamorphic rocks include slate, schist, gneiss, and marble. Now, back to Mammoth Hot Springs.
This area is one of the world's best examples of travertine-depositing hot springs. Travertine is a form of limestone deposited by mineral springs, especially hot springs. It is form by a process of rapid precipitation of calcium carbonate, precipitation being the formation of a solid in a solution or inside another solid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate.
This is one of Yellowstone's most dynamic hydrothermal areas. It features constantly change. For hundreds of years, Shoshone and Bannock Indians collected minerals from Mammoth Hot Springs for white paint. These minerals contribute to the beauty of the terrace structures, along with heat, a natural "plumbing" system, water, and limestone. Volcanism supplies the heat. As I've mentioned already, Yellowstone was the site of catastrophic volcanic eruptions, the last being 640,000 years ago, which formed a giant caldera. The magma chamber beneath Yellowstone provides the heat for the parks hydrothermal features, including Mammoth Springs, which is more than 20 miles north of the caldera. At Mammoth, a network of fissures and fractures forms the "plumbing" system that allows hot water from underground to reach the surface. Maximum water temperature here is 165 degrees. The water comes from rain and snow falling on the surrounding mountains and seeping deep into the earth where it is super-heated. Small earthquakes are thought to keep the plumbing open. Limestone, deposited here millions of years ago when a vast sea covered this area, provides the final ingredient. Hot water with dissolved carbon dioxide makes a weak solution of calcium carbonate, the primary chemical compound in limestone. At the surface, the calcium carbonate is deposited in the form of travertine, the rock that forms the terraces of Mammoth Hot Springs.
These terraces are living sculptures, shaped by the volume of water, the slope of the ground, and objects in the water's path. They are changing constantly.
Here, as in few other places on earth, rock forms before your eyes.
Colorful thermophiles (heat-loving microorganisms) create a changing palette in the flows.
Living Color Shimmering in this hot spring is a living palette of color. Billions of heat-loving microorganisms called "thermophiles" carpet the spring. Finding a Niche As you look at the spring's patchwork of colors, you are looking at a world of thermophiles. Many species flourish here, each in a unique niche created by subtle differences in the spring.
  • Temperatures vary - spots too hot or too cool for some are perfect for other thermophiles.
  • Gases, most potent at the vent, are nutritious for some, but deadly for others.
  • Swirling water or calm pools create different living conditions.
  • The formation's miniature hills and valleys capture light and cast shadows- habitats for sun or shade-loving thermophiles.
You are looking at billions of microorganisms living and prospering amid gases and heat- conditions that are lethal to humans. Some scientists study these remarkable thermophiles and their hot spring habitats to determine whether other worlds might support life. They are also learning about the kinds of evidence to search for in their quest to find life beyond Earth.
I found it amazing that this little aster could grow in this seemingly inhospitable environment.
Minerva Terrace A Living Sculpture The delicate travertine formations around you were all created by hot spring water. Heated by Yellowstone's volcano, water travels through buried limestone, then bubbles to the surface to deposit travertine. Named in the late 1800's for the Roman goddess of art, Minerva Spring sculpted Minerva Terrace. The spring sometimes flows abundantly, as shown in this 1977 photograph. At other times it is completely dry, illustrating the changing nature of Mammoth Hot Springs. Shifting Springs Terrace Mountain, located about two miles from here, is capped by more than one hundred feet of travertine. Shaped by ancient hot springs, the mountaintop is now at rest, but new springs are reshaping neighboring hills. Underground Mysteries Flowing through a complex network of underground channels, hot spring water often changes course. New channels form and others become blocked as minerals accumulate or dissolve. Earthquakes also open or close cracks in the system. Mammoth Hot Springs is constantly changing. New springs flow - or old springs may flow again- as others become dry. But for more than a century, the general level of activity has remained consistent.
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1 comment:

Marilyn said...

Lovely. At first glance, the walls of the pools almost look manmade - they are just that perfect.

It makes you wonder what went through the minds of the first people who came across this area.