McDermitt Caldera

The McDermitt Caldera is a large, oval-shaped hole in the ground found west of the town of McDermitt in southeastern Oregon and northern Nevada in the United States. It measures about 28 miles wide from north to south and 22 miles from east to west. This caldera was created by the same hotspot that formed the Yellowstone hotspot around 16.4 million years ago.

The highest point in the McDermitt Caldera is Jordan Meadow Mountain, which reaches 6,816 feet above sea level. This mountain is part of the Montana Mountains in Nevada.

Long before people settled there, the area was home to the Shoshone and Northern Paiute people, who moved around the land. Later, in the mid-1800s, people began ranching there. The caldera holds important minerals, and people have mined mercury and uranium there in the past. Recently, scientists have started looking at the area for possible lithium mining.

The McDermitt Caldera is also a special place for wildlife. It helps protect endangered animals like the sage grouse and the Lahontan cutthroat trout. Even though these animals are struggling in other parts of the western United States, they are doing well here.

Geography

The McDermitt Caldera is located in a remote area near the border of Oregon and Nevada, west of the town of McDermitt and north of Winnemucca, Nevada. It has a shape like a raindrop, stretching north to south.

This caldera is part of a special dry area called an endorheic basin within the larger Great Basin region. The western part sits in the Trout Creek Mountains, and the northern part is in the Oregon Canyon Mountains. The area around the caldera is very dry, with little rain and big temperature changes, from very cold winters to very hot summers. The Cascade Range to the west helps create these dry conditions.

Geology

The McDermitt Caldera is one of the oldest volcanic areas linked to the Yellowstone hotspot. This hotspot created a line of volcanic features that stretch from southern Idaho to Yellowstone Caldera. As the North American plate moved, volcanic activity shifted northeast from the McDermitt area.

The McDermitt Caldera was formed when a lava dome collapsed about 16.4 million years ago. Before this, eruptions had built up the dome with rhyolite over about 19 million years. Later, a lake filled the caldera, leaving layers of varved sediments, diatomite, opal, and organic matter between lava flows and tuffs. More volcanic activity raised parts of the caldera, draining the lake, and minerals were carried upward through the sediments. The youngest volcanic activity here happened about 14.9 million years ago.

Other volcanic places in Oregon linked to the Yellowstone hotspot include Smith Rock, part of the Crooked River caldera, and the Columbia River Basalt Group, which is about the same age as McDermitt Caldera.

History

The Shoshone and Northern Paiute people lived in and around the McDermitt Caldera before the United States expanded into the area. They moved with the seasons and followed animals for food. In the 1800s, they had conflicts with American settlers but were later moved to reservations.

A U.S. Army fort called Fort McDermit was built nearby in 1866 and named after a soldier who died in a fight with local people. The nearby town took its name from the fort, which also gave its name to the caldera.

Ranching by American settlers began during these conflicts and continues today. Roads passed close to the caldera, linking places like Virginia City, Nevada and Silver City, Idaho.

During the 20th century, miners searched for valuable materials like mercury and uranium, with uranium found in 1953. Lithium was discovered in the 1970s, and the last mercury mine closed in 1992. Today, there are still old mines and waste from mining left behind.

In 2017, the government allowed exploration for lithium, but many groups including native tribes and environmentalists strongly oppose this.

Economic resources

The McDermitt Caldera holds important minerals buried deep underground. During the 1900s, people mined mercury and uranium from more than eight places in the area. Mercury came mostly from a mineral called cinnabar. The McDermitt Mine in Nevada was the last place in the United States to mine mercury before it closed.

Uranium was taken from a special rocky area at the Moonlight mine. The uranium was found in minerals called uraninite and coffinite. Scientists think these uranium deposits are about the same age as the caldera itself—around 16.1 million years old. The caldera also has other valuable minerals like antimony, cesium, and lithium, which could make it one of the largest lithium mining areas in the world.

The Thacker Pass lithium deposit is especially important. In 2017, it was called the most significant source of lithium-clay in the United States. More exploration for lithium was allowed in 2025. Most of the land here belongs to the Bureau of Land Management. Besides mining, some ranchers use the land for their cattle, but there has been concern about how new mines might affect ranching.

Ecology

The McDermitt Caldera is a shrub–steppe environment with grasses and sagebrush. It is an important home for endangered animals like sage grouse and Lahontan cutthroat trout. Sage grouse use many mating sites in this area, and it has been a key place for them, even though their numbers have dropped a lot since the 1960s.

In the late-1980s and 1990s, laws were made to change ranching practices to help protect these animals, especially near water areas. Because of ecological concerns, there has been opposition to new mining operations. Until 2017, the government did not consider new mining claims, but rules were changed during a later presidency to make it easier. Many groups, including environmental organizations, Native American tribes, and ranchers, have spoken out against development because it could harm the environment and their way of life.