Iron Spring Creek © 2010 Bo Mackison

This mound of geyserite to the left of the creek indicates that there have been geysers in this part of Yellowstone National Park for eons.

The run off from pools and geysers in the Black Sand Geyser Basin flows into Iron Spring Creek. The reddish-brown color of the creek, however, is not from iron, but from a reddish brown algae that is present in the creek because of thermal warming.

This is another sunrise photograph.

The temperature had dropped to 28˚F on this early October morning, and so there was a magnificent display of steaming hot pools in the basin. The early light bathed the whole area in luminous beauty.