What is a Coulee?

What is a Coulee? Dramatic coulees of eastern Washington's Channeled Scablands were created by powerful Ice Age Floods that dug aggressively into the Columbia River Basalt flows.
Coulees are unique, box-shaped valleys created quickly by Ice Age Floods of the Pleistocene Epoch. Coulees are most notably found in the Channeled Scablands of eastern Washington. Famous examples include Grand Coulee, Moses Coulee, and Frenchman Coulee.

This episode begins with Nick standing at the edge of Echo Coulee, just south of Frenchman Coulee. The classic look of a coulee is on display - flat coulee floor, vertical coulee walls, and no river in the coulee bottom. Beginning in the 1920's, geologist J Harlen Bretz tried convincing the science world that coulees like this one must be the result of large-volume, short-lived flooding events during the Ice Age. Opposition to Bretz's arguments lasted many decades, but today, the scientific community embraces the story of the Ice Age Floods.

After some nifty aerials by flying ace Tom Tabbert, the episode resumes with Nick standing at the base of a popular climbing route in Echo Coulee. A discussion of the fractured nature of basalt reveals that the basalt bedrock of eastern Washington - the Columbia River Basalt Group - plays a large role in coulee development. The vertical and horizontal fracture sets, created 15 million years ago when the lava cooled, aided the floodwater's erosive ability. The result? Coulees with vertical and horizontal components directly controlled by the fractures in the basalt bedrock.

Filmed in June, 2013.
Episode written by Nick Zentner and Tom Foster.
Video, Sound, & Editing: Tom Foster

Видео What is a Coulee? канала hugefloods