Yellowstone National Park is home to such an array of thermal features from geysers, fumaroles (steam vents), hot springs, geyser basins and mudpots. The park was founded in 1872 and has the distinction of being the very first national park in the United States. To say that the park is massive would be an understatement. The park measures almost 3,500 square miles, and, to see it properly, at least 3 or 4 days are required (a week is better). My favorite area in the park is the Mammoth Hot Springs area, located in the northwest Wyoming corner that also includes part of Montana. This section is home to numerous hot springs that were created over thousands of years, as hot water from the surrounding Norris Geyser Basin deposited calcium carbonate as the water cooled. This left limestone and rock formations throughout the area. I am not sure how the Orange Spring Mound (pictured above) is technically classified but it can be found in the Upper Terrace. The formation is very different in shape than the others on the Upper Terrace. As I came to this formation, I noticed the steam coming out of its right side and thought that the light accentuated its color and steam.