Yellowstone hotspot

The Yellowstone hotspot is a volcanic hotspot in the United States. It has caused big volcanic activity in Idaho, Montana, Nevada, Oregon, and Wyoming. It formed when the North American tectonic plate moved over it, making a chain of volcanic places.

This hotspot made the eastern Snake River Plain through many huge eruptions. These eruptions made big volcanic depressions called calderas. Some of these calderas are the Island Park Caldera, Henry's Fork Caldera, and the Bruneau-Jarbidge caldera.

Today, the hotspot is under the Yellowstone Caldera, one of the most famous volcanic places in the world. Its most recent big eruption, called the Lava Creek Eruption, happened 640,000 years ago. This eruption made the Lava Creek Tuff and shaped the current Yellowstone Caldera.

The Yellowstone hotspot is just one of a few volcanic hotspots under the North American tectonic plate. Another example is the Anahim hotspot, located further west. These hotspots help scientists learn about how Earth's surface has changed over millions of years.

Snake River Plain

The eastern Snake River Plain is a low area that runs across the Basin and Range mountains. It follows the movement of the North American Plate. Under its dark rocks, called basalts, there are older light-colored rhyolite lavas and layers of ash from ancient eruptions, known as ignimbrites. As the Earth's outer layer, the lithosphere, moved over a hot spot deep in the Earth, it caused these eruptions. Later, volcanoes added fresh basalt lava flows in places like the Craters of the Moon National Monument and Preserve.

The central part of the Snake River Plain has layers from old lakes and streams, called lacustrine and fluvial sediments. One famous spot here is the Hagerman Fossil Beds.

Nevada–Oregon calderas

The McDermitt volcanic field is on the border of Nevada and Oregon. It is often called the start of the Yellowstone Hotspot. New studies show that the area affected by this old volcanic activity is bigger than we thought. Three new silicic calderas were found in northwest Nevada, west of the McDermitt volcanic field. These include the Virgin Valley Caldera and the McDermitt Caldera. These calderas formed between 16.5 and 15.5 million years ago. They range from 15 to 26 kilometers wide and covered about 5,000 square kilometers with volcanic rocks.

As the hotspot moved under what is now Nevada and Oregon, it changed the local ecology. It broke up old habitats and created more varied landscapes in western North America. The Bruneau-Jarbidge volcanic field erupted between ten and twelve million years ago. It created a wide caldera and spread a thick layer of ash. This volcanic ash was carried far by winds, covering a large part of the Great Plains. At the Ashfall Fossil Beds in northeastern Nebraska, a thick layer of ash preserved many fossils, including rhinoceroses. These fossils give us valuable insights into ancient life.

Volcanic fields

The Twin Falls and Picabo volcanic fields were active around 10 million years ago. The Picabo Caldera made the Arbon Valley Tuff about 10.2 million years ago.

The Heise volcanic field in eastern Idaho had big eruptions starting 6.6 million years ago. These eruptions made a lot of rhyolitic magma. The last big eruption, the Kilgore Tuff, happened 4.5 million years ago.

Yellowstone Plateau

See also: Yellowstone Caldera

The Yellowstone Plateau is a volcanic area with four large sunken regions called calderas. One of these, the Henry's Fork Caldera in Idaho, formed over 1 million years ago and is still easy to see today. It is inside an even larger caldera called the Island Park Caldera, which stretches into Yellowstone Park.

The Island Park Caldera is much bigger. It made a huge amount of ash over 2 million years ago that spread far across North America. The most recent and famous caldera is the Yellowstone Caldera, which formed around 640,000 years ago. It is still active, with small steam eruptions, but scientists think it might be near the end of its activity.

Eruptive history

The Yellowstone hotspot has caused many volcanic eruptions in several U.S. states over millions of years. These eruptions made big areas of lava and changed the land a lot.

Important eruptions include the Yellowstone Caldera about 640,000 years ago, which made huge amounts of lava. Before that, the Island Park Caldera erupted around 2.1 million years ago. Even earlier, around 16 million years ago, the Columbia River Basalt Province had massive lava flows that covered large parts of Washington, Oregon, and Idaho.