<< Opal Pool at Midway Geyser Basin
Hot Springs are closely related to geysers, but their underground channel systems are not constricted. Water circulates to the surface where heat escapes through evaporation or runoff. The cooler water returns to the underground system, keeping it in equilibrium.
<< Blue Star Spring at Upper Geyser Basin
Many of the bright colors found in Yellowstone’s hydrothermal basins come from microorganisms which are called thermophiles and that thrive in hot temperatures So many individual microorganisms are grouped together—trillions!—that they appear as masses of color.
Different types of thermophiles live at different temperatures within a hot spring and cannot tolerate much cooler or warmer conditions. 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.
<< Silex Spring at Fountain Paint Pot
Clink the link below to see more about the "Anatomy of a Hot Spring"