Badlands National Park: Tunnel to the Past

April 02, 2019

Badlands National Park Tunnel to the Past
Photographer: George Seielstad 
Summary Author: George Seielstad 

The colorful hillside in this carved canyon features the Yellow Mounds of Badlands National Park in western South Dakota. They formed some 67 million years ago when mid-continent seas flooded this area, depositing their sediments. The humps atop the mounds belong to the Chadron Formation, deposited 34-37 million years ago when rivers flowing from the newly uplifted Black Hills (about 100 miles or 160 km to the west) unloaded their sediments.

Rising in the distance, on the left side of the photo, is the Brule Formation (30-34 million years old). It's topped by Rockyford Ash (30 million-year-old volcanic ash). The peaks belong to the Sharps Formation (deposited 28-30 million years ago). This process began when the Cheyenne River flowed into this area about 500,000 years ago initiating large-scale erosion. The Badlands are rich in fossils that show a steady transition of life, from that adapted to cool, dry climates (bottom layers) to open shrub-land (upper layers). Photo taken on September 28, 2017.

Photo Details: Nikon D500 camera; 18-300mm Nikkor lens; 26 mm (39mm equivalent); f/10; 1/320 second exposure.