Why does this river slice straight through a mountain range? After 150 years, scientists finally know

The Gates of Lodore mark the beginning of the Green River's path through the Uinta Mountains. Scott Alan Ritchie / shutterstock

The western US is a geologists’ dream, home to the Rocky Mountains, the Grand Canyon, active volcanoes and striking sandstone arches. But one landform simply doesn’t make sense.

Rivers normally flow around barriers. The Danube river, for example, flows between the Alps and the Carpathians, twisting and turning to avoid the mountains.

But in north-western Colorado, one river does the opposite.