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When you travel across the United States, you can see many sights made by volcanoes. You know what cone-shaped volcanoes look like. But keep an eye out for many other landmarks.
Some volcanoes build mountains, but only when they are active. When they stop erupting, they start to wear down, or erode. After a long time, only parts of the mountain are left.
Other volcanoes don’t build mountains. Instead, their lava floods the land. It drowns hills and valleys. Sometimes during an eruption, the top of a volcanic cone falls in and a crater forms. A crater is also called a caldera. Craters can be anywhere from hundreds of feet wide to tens of miles across!
Let’s visit some of America’s volcanic landmarks.
▲ Grand Canyon, AZ: About a million years ago, lava poured over the west walls of the Grand Canyon. It plugged up the Colorado River. Time passed, and the river cut through the rock. It formed Lava Falls. Rafting through the rapids at Lava Falls can be a thrill!
◀ Ship Rock, NM: Ship Rock is a lava plug that formed inside a volcano. Erosion wore away the volcanic cone around it. Now it towers above the desert like a skyscraper.
Petrified Forest, AZ: These trees are actually fossil logs. They may have been pulled up when a volcano exploded. That happened about 200 million years ago. The trees were buried by mudflows, like when Mount St. Helens erupted in 1980. Minerals in the volcanic ash turned the trees to rock. ▶
▲ Crater Lake, OR: Some craters fill with water and become lakes. Crater Lake is 2,000 feet deep. It’s the deepest lake in the United States. It’s so deep, you could stack two Eiffel Towers in it!
◀ Sunset Crater, AZ: This classic cinder cone is only 900 years old. Where does it get the sunsetlike colors? They come from minerals such as sulfur and iron.
Craters of the Moon National Monument, ID: You may not get to the Moon, but you can see this alien world. These lava fields and cinder cones are in Idaho. Apollo astronauts trained here before going to the Moon. ▶
◀ Mount St. Helens, WA: A “forest of stone” formed here about 1,900 years ago. Lava covered the slopes and burned giant fir trees. All that’s left are the hollow shells of the trees. They make special places for exploring.
▲ Hudson Palisades, NJ: About 200 million years ago, North America and Africa were part of one giant continent. Then they began drifting apart. Giant cracks formed near where New York City is now. Magma was pushed out, and you can see it today. It’s in the high basalt cliffs along the west side of the Hudson River.
Old Faithful
▲ Yellowstone National Park, WY: Steam and hot water gush from Old Faithful about once an hour. Yellowstone National Park sits on a hotspot. It has more active geysers than the rest of the world put together! Yellowstone hasn’t had an eruption for 70,000 years. But the geysers remind us the area is still active.
◀ A geyser is like a teakettle under the ground. Rainwater seeps into the Earth. Magma heats the water until it turns into steam. The hot steam rises and jets into the sky as a geyser.
