Small floods can carve big canyons

Thu, 19 Jan 2017 13:41:27 -0500

Moses Coulee, amid the Channeled Scablands in Washington state, was carved by floods that burst from massive, naturally dammed glacial lakes during the last ice age. Credit: Williamborg.

Through the early 20th century, geologists argued over how the giant canyons of the Channeled Scablands in Eastern Washington were formed. Ultimately, a theory proposed by J Harlen Bretz in the 1920s — that the canyons were carved by catastrophic, short-lived outbursts of floodwaters unleashed when natural dams holding back glacial lakes collapsed — was shown to be correct. Controversy still exists, though, about the size of these ancient floods.

Travels in Geology: Rafting the Pacific Northwest's heavenly Hells Canyon

Wed, 02 Sep 2015 15:07:19 -0400

Hells Canyon, the deepest gorge in North America, is challenging to get to, but it's great to raft or boat. Credit: Mary Caperton Morton.

Hells Canyon forms part of the Oregon-Idaho border. Credit: both: K. Cantner, AGI.

Why would you ever visit a place called Hells Canyon? Especially given how hard it is to get there: Few roads and only steep, difficult trails run down into the 2,400-meter-deep gorge — the deepest canyon in North America — which forms part of the border between Oregon and Idaho. Despite its remote and rugged challenges, however, Hells Canyon has attracted visitors for thousands of years, from the Clovis people and Native Americans to turn-of-the-century gold miners, sheep ranchers and homesteaders.

Canyon on EARTH Magazine

Small floods can carve big canyons

Travels in Geology: Rafting the Pacific Northwest's heavenly Hells Canyon