Yellowstone arrives

For 15 million years, the land that would become Yellowstone National Park crept toward its destiny--a  hot spot that created a string of volcanoes all the way from Nevada to Wyoming.  Two millions years ago, it arrived, yielding its first and largest eruption. When the Huckleberry Ridge Caldera Eruption occurred, the southwestern quarter of Yellowstone was blasted away, producing 2,500 cubic kilometers of ash. And that was just the beginning.

Map of fallout distribution from Yellowstone.

Yellowstone remains "one of the world's largest, most explosive and most unusual volcanos," according to a sign in a visitor's center.

Two other catastrophic eruptions followed, 1.3 million* and 640,000 years ago.** (*Henry's Fork Caldera Eruption, 280 cubic kilometers of ash; **Yellowstone Caldera Eruption, 1,000 cubic kilometers of ash.)  Thirty smaller eruptions have since occurred, the most recent one 70,000 years ago. "Yellowstone may erupt again."

Yellowstone's three caldera eruptions had global impacts. Those eruptions were from 28 to 250 times larger than the 1991 Mount Pinatubo eruption in the Philippines, which sent a 3,000 mile-wide cloud of ash and gases into the atmosphere, cooling global temperatures for about two years.


Intense heat welded the mountains of ash into rock called "tuff."

Beneath more solid rock, a bed of tuff is heavily eroded.

The hotspot below Yellowstone uplifted the land, making Yellowstone cold enough for massive glaciers to form locally and rework the landscape. About 20,000 years ago, Yellowstone's  Canyon area was buried under 4,000 feet of ice.


Then the volcano's chemistry took over, and the effects are clearly visible in what is called the Grand Canyon of Yellowstone. Mineral stains mark the sites of hot springs and steam vents in the canyon walls. It's a sight to behold.

Tuff walls of the canyon streaked by the chemistry of the volcano.

Getting to the bottom of this canyon is not a trip for the faint of heart -- or asthma patients. Once the journey involved 528 steps and rope ladders.  Now there is the luxury of a steel stairway of only 328 steps that descend three-fourths of the way to the bottom for a view of the falls. A sign at the top of "Uncle Tom's Trail" warns visitors to "take your time, enjoy the scenery, and rest often."

Those who descend are treated to a rainbow from the spray of the canyon's waterfall.

"Uncle Tom's Trail" to viewpoint.

The fiery landscape of Yellowstone became the substance of legends.

An example--according to Native American tradition, Daw-Kee (God) promised land in Yellowstone to any tribe that  could yield a volunteer to plunge into Dragon's Mouth, a boiling cauldron at Mud Volcano. A tribe produced such a young man, whose scalding death transformed the land into a beautiful and abundant homeland for the Kiowas.

Steam blows from the cave known as Dragon's Mouth Spring, a moaning boiling, sloshing and deadly cauldron.

Two thirds of the world's geysers are found in Yellowstone, which also is a host to hundreds of steam vents.

In Norris Geyser Basin, steam vents and bubbling pools churn constantly.

This continuous vent suggests a sagging tea kettle.

A stinking continuous column of steam jets from a vent at Norris Basin.

Chemistry and heat-loving bacteria give this stream its verdant hue.

Elsewhere in Yellowstone, acidic water and steam, along with heat, accelerate nature's normally gradual process of converting rock to clay.

A motorist seems oblivious to the ominous threat of the cliff beside the highway.

Another view of the rock formation shaping the cliff.

Virtually oblivious to the geophysical forces beneath, a bison, shedding its winter coat, ambles across the highway

Love,
Robert


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