Yellowstone hotspot facts for kids
Schematic of the hotspot and the Yellowstone Caldera
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Past locations of the hotspot in millions of years
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| Country | United States |
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| State | Idaho/Montana/Wyoming |
| Region | Rocky Mountains |
| Coordinates | 44°26′N 110°40′W / 44.43°N 110.67°W |
The Yellowstone hotspot is a special place deep under the Earth. It causes a lot of volcanic activity in parts of Idaho, Montana, Nevada, Oregon, and Wyoming. Imagine a giant, hot plume of rock rising from deep inside the Earth. As the North American Plate (the huge piece of Earth's crust we live on) slowly moves over this hot spot, it creates volcanoes.
This hotspot helped create the eastern Snake River Plain with many huge eruptions. These eruptions formed giant bowl-shaped craters called calderas. Some of these include the Island Park Caldera, Henry's Fork Caldera, and the Bruneau-Jarbidge caldera. Right now, the hotspot is located under the famous Yellowstone Caldera.
The last massive eruption from this hotspot happened about 640,000 years ago. It was so big it's called a supereruption! This event created the Lava Creek Tuff rock formation and the most recent Yellowstone Caldera. The Yellowstone hotspot is one of several such hot spots under North America. Another example is the Anahim hotspot.
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The Snake River Plain: A Volcanic Highway
The eastern Snake River Plain is a long, flat area that stretches across Idaho. It looks like a big ditch cutting through mountains. This plain formed as the North American Plate moved over the Yellowstone hotspot.
Deep under the ground, you can find old lava and ash from these ancient eruptions. Later, newer volcanoes erupted and covered parts of the plain with fresh basalt lava. A great example of this is the Craters of the Moon National Monument and Preserve.
The middle part of the Snake River Plain is similar. But it also has thick layers of sediment from old lakes and rivers. This is where you can find amazing fossils at places like the Hagerman Fossil Beds National Monument.
Ancient Calderas in Nevada and Oregon
The Yellowstone hotspot started its journey many millions of years ago. It created many volcanoes and calderas in what is now Nevada and Oregon. Scientists have found several large calderas in northwest Nevada. These include the Virgin Valley Caldera and McDermitt Caldera. They formed about 15.5 to 16.5 million years ago. These ancient calderas were huge, some up to 26 kilometers (about 16 miles) wide. They covered vast areas with hot volcanic ash and rock.
The hotspot's movement changed the landscape a lot. It created new mountains and valleys. This also led to different types of environments for plants and animals.
The Bruneau-Jarbidge Eruption and Fossil Beds
About 10 to 12 million years ago, the Bruneau-Jarbidge volcanic field erupted. This was a massive event that created a huge caldera. It also sent a thick layer of ash high into the sky.
Close to the eruption, animals were caught in fast-moving, super-hot clouds of gas and ash called pyroclastic flows. Farther away, animals suffered from the ash that fell from the sky. A famous example is the Ashfall Fossil Beds in northeastern Nebraska. This site is about 1,000 miles (1,600 kilometers) away from the Bruneau-Jarbidge volcano!
At Ashfall, a thick layer of ash covered the land. It preserved the remains of many animals, including over 200 fossilized rhinoceros. Scientists can tell this ash came from the Bruneau-Jarbidge eruption. They do this by studying its unique chemical makeup and the shape of its tiny crystals. This shows how far-reaching the effects of these giant eruptions can be.
Other Ancient Volcanic Fields
The Yellowstone hotspot left a trail of volcanic activity. Here are some other important areas it created:
Twin Falls and Picabo Volcanic Fields
About 10 million years ago, the Twin Falls and Picabo volcanic fields were active. The Picabo area had a caldera that erupted. It created a rock formation called the Arbon Valley Tuff.
Heise Volcanic Field
The Heise volcanic field in eastern Idaho was very active. It had huge, explosive eruptions that formed calderas. These eruptions started 6.6 million years ago and continued for over 2 million years.
Four massive eruptions happened here. The first three created a total of at least 2,250 cubic kilometers (about 540 cubic miles) of magma. The last and largest eruption, called the Kilgore Tuff, happened 4.5 million years ago. It released 1,800 cubic kilometers (about 430 cubic miles) of ash!
The Yellowstone Plateau: Home of Giant Calderas
The Yellowstone Plateau is a special area with four huge, overlapping calderas. Even parts of Lake Yellowstone were formed by smaller eruptions! For example, West Thumb Lake was created by an eruption about 174,000 years ago.
Henry's Fork Caldera
The Henry's Fork Caldera in Idaho formed about 1.3 million years ago. This eruption released over 280 cubic kilometers (about 67 cubic miles) of magma. It created a rock layer called the Mesa Falls Tuff. This caldera is about 29 kilometers (18 miles) long and 37 kilometers (23 miles) wide. You can still see its curved edges clearly in the Island Park area.
The Henry's Fork Caldera is unique because it's one of the few calderas from the Yellowstone hotspot that is still easy to see today. The Henry's Fork of the Snake River flows right through it. Harriman State Park is also located within this ancient caldera.
Island Park Caldera
Even older and much larger is the Island Park Caldera. It measures about 93 kilometers (58 miles) by 64 kilometers (40 miles). This caldera was formed by a massive supereruption 2.1 million years ago. This event produced an incredible 2,500 cubic kilometers (about 600 cubic miles) of ash! This ash, known as the Huckleberry Ridge Tuff, has been found as far away as southern California and near the Mississippi River. Sometimes, people call this the First Phase Yellowstone Caldera.
Yellowstone Caldera: The Youngest Giant
The youngest and most famous caldera is the Yellowstone Caldera. It formed 640,000 years ago and is about 55 kilometers (34 miles) by 72 kilometers (45 miles) wide. Since that huge eruption, there have been smaller lava flows and less violent eruptions. The most recent lava flow happened about 70,000 years ago. A large eruption around 150,000 years ago created the West Thumb of Lake Yellowstone. Even smaller steam explosions have occurred, like one 13,800 years ago that left a 5-kilometer (3-mile) wide crater at Mary Bay.
Is the Yellowstone Hotspot Changing?
Scientists study the types of magma that erupt from these volcanoes. They look at things like oxygen isotopes in the rocks. Some studies suggest that the Yellowstone hotspot might be changing. This could mean that the hotspot is using up the crust above it. If this is true, the Yellowstone volcano might be entering its final stages.
However, it could also mean that another huge eruption is still possible. It might take another 1 to 2 million years for the North American Plate to move enough for a new supervolcano to form to the northeast. A study from 2020 also suggested that the hotspot's power might be decreasing.
A Timeline of Yellowstone's Eruptions
The Yellowstone hotspot has a long and exciting history of eruptions. Here are some of the major events:
Recent Eruptions (within the last 15,000 years)
- About 2,270 years ago: The Wapi Lava field and King's Bowl blowout in Idaho.
- About 3,250 years ago: The Hell's Half Acre lava field in Idaho.
- About 8,400 years ago: The Shoshone lava field in Idaho.
- Between 15,000 and 2,000 years ago: The Craters of the Moon National Monument and Preserve formed from many eruptions.
Major Caldera-Forming Eruptions
These were some of the biggest and most powerful eruptions, forming the giant calderas we see today. The VEI (Volcanic Explosivity Index) measures how big an eruption is, with 8 being the largest.
- Yellowstone Caldera (640,000 years ago): A VEI 8 supereruption that created the current Yellowstone Caldera. It released over 1,000 cubic kilometers (240 cubic miles) of Lava Creek Tuff.
- Henry's Fork Caldera (1.3 million years ago): A VEI 7 eruption that formed this 16-kilometer (10-mile) wide caldera. It produced 280 cubic kilometers (67 cubic miles) of Mesa Falls Tuff.
- Island Park Caldera (2.1 million years ago): A VEI 8 supereruption, forming a caldera 100 by 50 kilometers (62 by 31 miles). It released 2,450 cubic kilometers (588 cubic miles) of Huckleberry Ridge Tuff.
Heise Volcanic Field Eruptions (4.45 to 6.62 million years ago)
The Heise volcanic field had several huge eruptions:
- Kilgore Caldera (4.45 million years ago): A VEI 8 eruption that produced 1,800 cubic kilometers (430 cubic miles) of Kilgore Tuff.
- Blacktail Caldera (6.62 million years ago): This VEI 8 eruption created a caldera 100 by 60 kilometers (62 by 37 miles). It released 1,500 cubic kilometers (360 cubic miles) of Blacktail Tuff.
Older Eruptions (8.72 to 16.548 million years ago)
- Grey's Landing Ignimbrite (8.72 million years ago): A VEI 8 eruption that released at least 2,800 cubic kilometers (670 cubic miles) of volcanic material.
- McMullen Supereruption (8.99 million years ago): Another VEI 8 event, producing at least 1,700 cubic kilometers (408 cubic miles) of material.
- Twin Falls and Picabo Volcanic Fields (8.6 to 10 million years ago): Active periods in Idaho.
- Bruneau-Jarbidge Volcanic Field (10.0 to 12.5 million years ago): This field in Idaho caused the famous Ashfall Fossil Beds eruption.
- McDermitt Volcanic Field (around 15 to 16.5 million years ago): This area on the Nevada/Oregon border had several overlapping calderas. One example is the Washburn Caldera (16.548 million years ago), which released 250 cubic kilometers (60 cubic miles) of Oregon Canyon Tuff.
- Columbia River Basalt Province (14 to 17 million years ago): The Yellowstone hotspot helped trigger a massive outpouring of lava in Washington, Oregon, and Idaho. This included the Columbia River flood basalts (175,000 cubic kilometers or 42,000 cubic miles of lava) and Steens flood basalts (65,000 cubic kilometers or 15,600 cubic miles of lava).
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