Floating down the Cheyenne River is like a meander through time. Prickly pear and yucca tap the seams between multi-hued geologic age-layers, like fossil-rich black Pierre shale and the Spearfish Formation's red racetrack. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.