Amazing Planet

This Volcanic Crater In Oregon Forms America's Deepest Lake

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One of the most awe-inspiring members of the Ring of Fire—the the global arc that contains 75 percent of the world's active volcanoes—is Oregon's Crater Lake National Park. Its namesake is the deepest lake in the United States, but it's not connected to any rivers—all of its water comes from precipitation. That's why it's such a striking shade of blue.

From Outie to Innie

Before the lake formed, the volcano known as Mount Mazama stood in its place. That mountain formed 500,000 years ago as a result of one tectonic plate being forced beneath another, raising an edge to form the volcano's 12,000-foot (3,700 meter) peak. Well, plate tectonics giveth and plate tectonics taketh away: 7,700 years ago, the volcano erupted, wiping out all life for thousands of miles. Then, it erupted again, collapsing in on itself and forming a crater up to 6 miles (10 km) wide and 3,900 feet (1,200 meters) deep.

Crater Lake Today

Today, however, it's only 1,943 feet (592 meters) at its deepest point. That's because volcanic rock fragments have been falling from its edges for thousands of years, slowly building up its bottom. It's also speckled with volcanic islands that formed in the leftover magma from the smoking volcano. The most famous of these is the Phantom Ship, whose jagged peaks tower from the water as high as 170 feet (52 meters). 

Despite the fact that it's many millennia old, Crater Lake still has some surprises up its sleeve. One of its more incredible details is how well it maintains its depths. Despite varied precipitation and evaporation through the seasons, its average depth remains pretty much the same all year round. And thanks to the fact that there's no sediment creeping in from tributaries, that depth is still, blue, and crystal clear.

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Crater Lake National Park

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