The deepest river gorge in North America is much younger than we thought

Countries & Cities · Published 30 September 2026 Swipe more like this →

In short: While the Grand Canyon is a global icon, Hells Canyon holds the title for North America's deepest river gorge. Spanning ten miles wide, this rugged landscape of the Western United States hides a geological secret: recent research suggests its formation began much more recently than previous estimates suggested.

Reaching depths of 7,993 feet, Hells Canyon is a massive geological feature carved by the Snake River. The canyon's complex history began 300 million years ago with volcanic arcs emerging from the Pacific Ocean. Over millions of years, these volcanoes subsided, allowing limestone and sedimentary rock to accumulate before the ocean plate collided with the North American continent between 130 and 17 million years ago.

For a long time, geologists believed the canyon began carving out of the plateau roughly 6 million years ago, following a period of basalt lava flows that smoothed the high plateau. However, a 2025 study has challenged this timeline, concluding that the canyon is actually younger than previously believed, with its formation beginning only 1.6 million years ago.

The landscape has been shaped by dramatic hydrological events, including a massive outburst flood from Lake Bonneville in Utah as recently as 15,000 years ago. Today, the canyon's character is defined by extremes: the river flows more than one mile below the Oregon rim and 7,400 feet below Idaho's Seven Devils Mountains, creating a dry, desert environment at the bottom contrasted by dense forests on the rims.

Human history in the canyon is equally intense. The area was home to the Nez Percé, Shoshone-Bannock, northern Paiute, and Cayuse tribes. Later, the region saw the arrival of gold miners in the 1860s and a tragic episode in May 1887, when 34 Chinese miners were killed in the Hells Canyon Massacre. While the canyon's inaccessibility defeated many early explorers, it remains a vital hub for modern hydroelectric power and recreation.

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