Nature & Science

Natural History of the Columbia River Gorge

Where did this place come from?

Once upon a time, 40 million years ago . . . 

Waterfall in a tight, rocky gorge.The natural story of the Columbia River Gorge begins with the fiery volcanoes of the Cascade Mountain Range. Over the centuries these volcanoes left lava and mudflows up to two miles thick. Remnants of these flows can still be seen in the cliffs of the Gorge. The Columbia River cut a deep canyon through the lava, ash and mud.

The greatest force in the Gorge’s creation was flooding. About 15,000 years ago, near the end of the last Ice Age, gigantic floods up to 1,200 feet deep swept down the river corridor and scoured its cliffs, leaving its tributary streams hanging high above the river’s bed. Today, many streams cascade down the cliffs creating one of the world’s greatest concentrations of waterfalls.

The walls of the Gorge were further altered by massive landslides. Recent geologic activity can be viewed today off I-84 at Dodson, where a wide flow of debris moved houses and wiped out a community’s infrastructure in 1996.

The natural elements of the Gorge adapt to its magnificent geology, creating a mosaic of ecosystems – from the wet, emerald forests of the western Gorge to pine-oak woodlands and the arid, grassy savannahs of the east. The Columbia River Gorge is the only sea level passage through the Cascade Mountain Range — from the river, the Gorge rises to 4,055-foot Larch Mountain, a rapid change from sea level to sub-alpine environment.

The Columbia River Gorge begins with the fiery volcanoes of the Cascade Mountain Range. Over the centuries these volcanoes left lava and mudflows up to two miles thick. Remnants of these flows can still be seen in the cliffs of the Gorge. The Columbia River cut a deep canyon through the lava, ash and mud.

The greatest force in the Gorge’s creation was flooding. About 15,000 years ago, near the end of the last Ice Age, gigantic floods up to 1,200 feet deep swept down the river corridor and scoured its cliffs, leaving its tributary streams hanging high above the river’s bed. Today, many streams cascade down the cliffs creating one of the world’s greatest concentrations of waterfalls.

The walls of the Gorge were further altered by massive landslides. Recent geologic activity can be viewed today off I-84 at Dodson, where a wide flow of debris moved houses and wiped out a community’s infrastructure in 1996.

The natural elements of the Gorge adapt to its magnificent geology, creating a mosaic of ecosystems – from the wet, emerald forests of the western Gorge to pine-oak woodlands and the arid, grassy savannahs of the east. The Columbia River Gorge is the only sea level passage through the Cascade Mountain Range — from the river, the Gorge rises to 4,055-foot Larch Mountain, a rapid change from sea level to sub-alpine environment.