• A bull elk bugles in Yellowstone National Park

    Yellowstone

    National Park ID,MT,WY

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  • Craig Pass Closed for the Season; Mammoth to Norris Closed Sept. 14-30

    The road linking West Thumb and Old Faithful is closed for the season—traffic should detour through West Thumb, Lake, and Canyon. The road from Mammoth to Norris is closed for two weeks—traffic should detour over Dunraven Pass. More »

Emerald Spring

Bubbles rise to the surface, and steam from the surface, of this brighly green-colored hot spring pool.
 

A hot spring's color often indicates the presence of minerals. In a clear blue pool, the water is absorbing all colors of sunlight except one, blue, which is reflected back to our eyes. Here in Emerald Spring's pool, another factor joins with light refraction to give this spring its color. The 27-foot (8 meter) deep pool is lined with yellow sulfur deposits. The yellow color from the sulfur combines with the reflected blue light, making the hot spring appear a magnificent emerald green.

Hot spring water can dissolve and transport sulfur from underground. The mineral can deposit and crystallize at the earth's surface, sometimes in hot spring pools.


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Did You Know?

Bear Cubs

Even though the animals of Yellowstone seem tame they are still wild. Feeding the animals is not permitted in any way, and all visitors must keep 100 yards away from wolves and bears, and 25 yards from other animals.