Science

Not one, but two super eruptions formed the colossal Yellowstone caldera

Not one, but two super eruptio...
The last time the Yellowstone supervolcano erupted, it caused a climate-altering volcanic winter
The last time the Yellowstone supervolcano erupted, it caused a climate-altering volcanic winter
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The last time the Yellowstone supervolcano erupted, it caused a climate-altering volcanic winter
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The last time the Yellowstone supervolcano erupted, it caused a climate-altering volcanic winter

According to new research, the colossal caldera of the Yellowstone supervolcano was created by not one, but two powerful and closely spaced eruptions that took place some 630,000 years ago. The super eruptions were powerful enough to affect the global climate as the planet was recovering from an ice age.

Supervolcanoes, such as the one resting beneath the Yellowstone National Park are capable of generating eruptions that dwarf those of their smaller cousins.

Evidence of the ferocity and magnitude of these eruptions is evident in the sheer size of the 45 x 30 mile (72 x 48 km) Yellowstone caldera – the crater that formed in the wake of the supervolcano's most recent bout of activity.

A team of geologists from the University of California Santa Barbara (UCSB) discovered a new record of the violent events that formed the Yellowstone caldera in two layers of ash and the shell sediments located off the Californian coast.

Underwater conditions in the Santa Barbara basin 630,00 years ago – around the time the explosive volcanic activity took place – was extremely well suited to creating an enduring record of the climate altering events.

This is partially due to the fact that, at the time, the aquatic environment was being fed by nutrients from deep within the ocean, which allowed for a high population of single-celled organisms known as foraminifera. The shells of the foraminifera, discovered in the sediment alongside the volcanic ash, play host to temperature dependent oxygen isotopes that can be used by geologists to determine the temperature of the sea in which they lived.

The low-oxygen environment at the seafloor in the Santa Barbara Basin discouraged the presence of burrowing bottom-dwelling animals that would otherwise have damaged the quality of the record by mixing the ash and sediment layers.

This combination of volcanic ash and shell sediment provided the team with an unprecedented high-resolution record of Yellowstone activity, revealing not one, but two eruptions, with a gap of 170 years in between.

An analysis of the foraminifera shells revealed that, after each of the super eruptions, the Santa Barbara Basin cooled by roughly 3 °C, as ash and volcanic sulfur dioxide released during events prevented light from the Sun from reaching and warming the Earth's surface.

According to the UCSB geologists, these closely spaced volcanic winters took place at a time when Earth was warming up following an ice age. The twin cooling periods, which lasted over 80 years a piece, had the effect of stalling the climate shift.

Source: The Geological Society of America

3 comments
ljaques
I sure wish "scientists" would get neutral again. This "recovering" from Ice Age and "delaying climate shift" verbiage is quite telling. The Earth goes through cycles which are not always comfortable for life, especially human. Why are they looking through flesh-colored glasses, allowing them to taint their objectivity? Well, if they were ever objective, seeing as they're looking for things which could have altered climate in the past. Please be neutral so we can all begin to believe in science again, folks. It's very, very important.
Don Duncan
ljaques: I agree. Words like "recovering" and "delaying" are subjective and assume the earth is a patient who has a healthy, normal condition and volcano eruptions are abnormal, decease.
Earth used to be a lot warmer and plants thrived along with very large animals. Was this bad? Abnormal? Why? But we are told a warmer earth is a catastrophic event even though it will happen slowly. Change is inevitable. Someday earth will be unliveable. We must leave or die.
But the rulers take our resources and build WMD. It's a race to see how we will become extinct, by suicide or waste of our technology until it's too late to escape into space.
HoppyHopkins
Global warming appears to be a good thing when it involves recovery from an ice age, but not when it is politically motivated I guess. I guess most people do not know that close to 10,000 years ago the continent of Antarctica was totally free of ice and the planet was a lot warmer that it is today. But true science has been given over to those who want to make it a puppet for political agendas