Because the rate of uranium radioactive decay is known, the age of the mineral can be calculated by measuring the amounts of parent uranium atoms and daughter thorium atoms in a sample of travertine. Scientists can therefore assume that any thorium measured within the crystal lattice of the mineral originated from the decay of the uranium that was locked into place when the aragonite or calcite formed. Other elements that are too big and don’t have the right ionic charge-like thorium, a product of the radioactive decay of uranium-are excluded. The spaces available between calcium, carbon, and oxygen atoms in the CaCO 3 mineral lattice allow for some trace elements that were dissolved in the water, like uranium, to be incorporated into the mineral structure. Travertine is a particularly interesting “geologic clock” because of the unique arrangement of calcium carbonate atoms in the aragonite and calcite. The green dashed line is the outline of Yellowstone Caldera and red lines are major paved roads. Map of Yellowstone National Park showing the location of major travertine deposits. Rates for calcium carbonate growth in the deep ocean or in terrestrial caves are even slower! One of the causes of the high deposition rate of travertine in Yellowstone is because thermophilic bacteria living in Yellowstone’s thermal waters encourage the precipitation of travertine. For example, fast-growing corals deposit travertine at an average rate of 1 millimeter per day, and the rate is ~0.2 millimeters per day for calcium carbonates deposited by cold freshwater (called tufas). Rates of travertine deposition at Mammoth Hot Springs in Yellowstone National Park are very high (~3 millimeters per day) compared to other calcium carbonate systems. C) A travertine deposit from the Hillside Springs Group near Old Faithful this travertine formed 3,000-4,000 years ago (photograph taken under research permit YELL-202). B) A few miles south of Mammoth Hot Springs, near Silver Gate, the highway passes through a landslide deposit composed of travertine blocks from Terrace Mountain these travertines formed several hundred thousand years ago. A) Travertine terraces actively forming at Mammoth Hot Springs. Yellowstone's hot water systems often show distinct gradations of living, vibrant colors where the temperature limit of one group of microbes is reached, only to be replaced by a different set of thermophiles.Photographs of travertine in Yellowstone. So many individual microorganisms are grouped together-trillions!-that they appear as masses of color.ĭifferent types of thermophiles live at different temperatures within a hot spring and cannot tolerate much cooler or warmer conditions. Many of the bright colors found in Yellowstone's hydrothermal basins come from thermophiles-microorganisms that thrive in hot temperatures. The spring's wide mouth and 42-foot depth provide a natural conduit for superheated water to circulate continuously to the surface. It is believed, however, that in the case of Crested Pool, no constrictions block the flow of water to the surface. Convection currents constantly circulate the water, preventing it from getting hot enough to trigger an eruption.Īt times, fierce, boiling waters within a hot spring (such as Crested Pool) can explode, shooting water into the air, acting much like a geyser. An open plumbing system allows the hot water to rise back to the surface unimpeded. Beginning as precipitation, the water of a hot spring seeps through the bedrock underlying Yellowstone and becomes superheated at depth. Hot springs are the most common hydrothermal features in Yellowstone. Blue, a color visible in light, is scattered the most and the color we see. The intense blue color of some springs results when sunlight passes into their deep, clear waters. Water temperatures within some springs exceed the boiling point.
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