That Time the American West Blew Up
PBS Eons・9 minutes read
A colossal eruption in ancient Colorado 28 million years ago created a massive Caldera, leaving behind thick ignimbrite deposits and forming the Fish Canyon Tuff, part of a series of super volcanoes that covered North America with ash. Despite the cataclysmic eruptions during the mid-tertiary ignimbrite flare-up, no major extinction events occurred, with significant fossil records preserved in places like the John Day Fossil Beds in Oregon.
Insights
- The Caldera formed in ancient Colorado from a massive eruption 28 million years ago was eight times the size of Denver, leaving behind ignimbrite deposits recording an eruption twice as powerful as Yellowstone's largest, part of a series of super volcanoes during the mid-tertiary ignimbrite flare-up.
- The Ring of Fire's formation along North America's Pacific Coast is due to plate tectonics, with volcanoes emerging where oceanic plates subduct under continental plates, resulting in magma ascent and explosive eruptions, as seen in the over 230 eruptions in North America due to the Farallon plate sinking under the North American plate, leading to the creation of the Rocky Mountains.
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Recent questions
How were the John Day Fossil Beds preserved?
Despite cataclysmic eruptions, the John Day Fossil Beds in Oregon were preserved due to no major extinction events occurring during the time period.
What caused the formation of North America's volcanoes?
The formation of North America's volcanoes along the Pacific Coast, known as the Ring of Fire, is due to plate tectonics, with volcanoes forming where oceanic plates sink under continental plates, causing magma to rise and form volcanoes.
What is the significance of the Fish Canyon Tuff deposit?
The Fish Canyon Tuff deposit is significant as it was a result of a massive eruption in ancient Colorado, creating a Caldera eight times the size of Denver, leaving behind thick deposits of ignimbrite, recording an eruption twice as powerful as Yellowstone's largest eruption.
How did life survive during the explosive eruptions in North America?
Despite the explosive eruptions in North America, life survived due to various survival strategies observed in modern eruptions like Mount St. Helens, where animals hid in burrows, lakes, or had large ranges to escape the immediate impact, with ecosystems quickly recovering due to nutrient-rich ash deposits.
What led to over 230 eruptions in North America?
The Farallon plate, an old oceanic plate, slid under the North American plate, forming the Rocky Mountains, but its slow sinking led to explosive eruptions due to the thick continental crust impeding magma flow, resulting in over 230 eruptions in North America.
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Summary
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Ancient Colorado's Massive Caldera Eruption
- 28 million years ago, a massive eruption in ancient Colorado created a Caldera eight times the size of Denver, leaving behind thick deposits of ignimbrite, recording an eruption twice as powerful as Yellowstone's largest eruption.
- The Fish Canyon Tuff, a result of this eruption, was part of a series of super volcanoes that covered North America with ash for millions of years during the mid-tertiary ignimbrite flare-up.
- Despite the cataclysmic eruptions, no major extinction events occurred during this time period, with some of North America's most significant fossil records preserved, like the John Day Fossil Beds in Oregon.
- The formation of North America's volcanoes along the Pacific Coast, known as the Ring of Fire, is due to plate tectonics, with volcanoes forming where oceanic plates sink under continental plates, causing magma to rise and form volcanoes.
- The Farallon plate, an old oceanic plate, slid under the North American plate, forming the Rocky Mountains, but its slow sinking led to explosive eruptions due to the thick continental crust impeding magma flow, resulting in over 230 eruptions in North America.
- Pyroclastic flows from these eruptions solidified into ignimbrites, with the Fish Canyon Tuff deposit still visible today, showcasing the immense scale of these eruptions.
- Despite the massive eruptions, life survived due to various survival strategies observed in modern eruptions like Mount St. Helens, where animals hid in burrows, lakes, or had large ranges to escape the immediate impact, with ecosystems quickly recovering due to nutrient-rich ash deposits.
