Horrible Today: Yellowstone Volcano Massive Eruption Terrifying Seconds America flying buried in ash

The Yellowstone volcanic system is known for its ash-flow tuffs—thick, compressed ash deposits from caldera-forming eruptions. But thinner ash beds from these eruptions were also deposited across the western and central USA.

In the late 1800s, geologists studying the Great Plains region of the United States puzzled over strange deposits. For example, a “white, flour-like earth” in Nebraska. Although initially thought to be from nearby hot springs, under the microscope it was determined that these deposits, which could be found across the region, were from volcanic ash that had rained down from some huge prehistoric eruption.

Some of the deposits came to be known as the “Pearlette volcanic ash” based on a description of conspicuous, silver-gray ash beds sitting atop river and lake sediments near the long-since abandoned Pearlette post office, about 22 kilometers (14 miles) north of Meade, Kansas.

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