How Did the Badlands National Park Form?

How Did the Badlands National Park Form?
In Badlands National Park, rocks have taken on a life of their own creating a landscape cut with canyons and a skyline marked by immense spires. Native Lakota and early trappers called it "bad land" because of its impenetrability.


Seventy-five million years ago, an ancient sea covered this landscape, depositing layers of sediment that hardened into Pierre Shale. This forms the base of the Badlands and is its oldest layer.



On top of the Pierre Shale, 30- to 34-million-year-old rock known as the Brule formation sits just below the Sharps formation, which contains ancient volcanic ash.

Water Erosion

About 500,000 years ago, rainwater began to seep through these layers at the relatively fast rate of one inch per year, exposing ancient rock and creating local rivers.

Additional Erosion

Wind and the effects of water seeping into cracks, freezing and then thawing also contributed to the region's erosion, most actively at the Badlands Wall, a 60-mile-long spine of buttes.


Article Written By Kelly Aspen

Kelly Aspen's writing focuses on natural places, cultural sites and wildlife. She has more than 10 years of experience as an editor and writer for various magazines, books and websites.

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