Bubbling mud-pots, mysterious fumaroles, steam spewing geysers and hot springs are what make Yellowstone National Park famous, but park visitors will also discover a vast land with thunderous waterfalls, majestic mountain ranges and a two million acres for the park's abundant wildlife. Formed eons ago when the earth's crust fractured, super-hot magma and ice-cold ground water continue create the lure of Yellowstone.
   Hot springs, the most common hydrothermal features in the park, start the cycle as rain or snow. The water eventually makes its way through cracks in the bedrock and become quickly heated by the underlying caldera. Openings in the crust allows the super hot water to rise back to the surface pools. Convection currents in the pool keep the water from getting too hot, which would trigger an eruption.
   Pictured here is the Grand Prismatic Spring, located in Yellowstone's Midway Geyser Basin. This immense spring is the largest hot spring in the United States, and third largest in the world. The bright colors, which make this spring such a star attraction, are formed by thermophiles. The microorganisms in this pool, numbered in the trillions, thrive in the hot water. Different temperatures produce different types of thermophiles. Appearing in masses, colors vary from blues and greens to yellows, oranges and browns. Quite a rainbow of colors, this display is certainly grand!

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