Yellowstone’s Colorful Canary Spring

September 28, 2021

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Photographer: Ray Boren

Summary Author: Ray Boren

The photos above show Yellowstone National Park’s northern Mammoth Hot Springs located near the Wyoming/Montana border. The spotlight feature of the hot springs is a hydrothermal complex in which geology and biology have created an array of multicolored terraces. Canary Spring, showcased in the photos above, is one of the most visually striking sites at the hot springs. The spring earned its distinctive name in the late 19th century because its yellowish color is reminiscent of canary birds’ bright feathers. Remarkably, the colors are due to living microorganisms called thermophiles, meaning “heat lovers”, which vibrantly coat the travertine.

The hot spring pools and bone-white travertine terraces of Mammoth Hot Springs, shown in the first image, gradually form as hot water heated by magma deep beneath Yellowstone ascends through a network of fractures and fissures underlying the dolomitic limestone. As the water rises to the surface, it deposits calcium carbonate dissolved from the limestone over the continually evolving terrace landscape. The underlying limestone was originally laid down by an ancient sea during the Mississippian age (about 350 million years ago) as a remnant of skeletal marine microorganisms and coral.

Life, death, and change are all around in one of the most extreme environments on Earth. Long dead tree trunks and branches, visible beside the busy boardwalk in the second photo, reach upward from the travertine that engulf them. Tiny but numerous thread-like thermophilic bacteria are nourished by odorous hydrogen sulfide gas rising through the vents. Meanwhile, adjacent cyanobacteria photosynthesizes sunlight for energy, just as flowering plants do to survive.

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