The most famous and most photographed geyser in the world.
Yellowstone is situated on an active volcano! Three major eruptions have occurred in the last 2.1 million years, the most recent only 650,000 years ago. Magma only 3-8 miles down provides the heat for the thermal features in Yellowstone. The Upper Geyser Basin, home of old faithful, is one of 3 large geyser basins along the Firehole River. We were there on a sunny day and we treated to eruptions from 3 other geysers in addition to Old Faithful. Along the many miles of boardwalk we passed numerous hot springs, mud pots, and fumaroles (steam vents).
At the north end of the park, the boiling water and steam travel to the surface through limestone, which dissolves to form a weak carbonic acid. When the hot water reaches the surface, calcium carbonate is deposited to form the travertine terraces of Mammoth Hot Springs. This is the same process that formed the travertine pools in Pamukkale, Turkey.
The visitor center in Canyon Village has an excellent display of the geology of Yellowstone. The Yellowstone River Canyon has a thundering waterfall and multi colored canyon walls resulting from the still-continuing geothermal activity.
The crater left after the last eruption has been
Acidic water dissolves the rock to form a bubbling slurry.
infilled with lava flows. Across the canyon from Tower falls is a magnificent example of lava flow cooling slowly to form Basaltic columns.
During the last ice age, 20,000 years ago, the ice was over 4,000 ft thick. Moraines and erratics (boulders carried by the glaciers) are strewn around the landscape. Glaciers disappeared from Yellowstone thousands of years ago, the result of global warming that started 20,000 years ago. When the ice retreated, homo sapiens entered Yellowstone around 11,000 years ago and there is evidence of their early existence.
I hope you enjoy the small selection of photographs.
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