POTD September 28, 2016: San Rafael Swell near Muddy Creek, Emery County

San Rafael Swell near Muddy Creek, Emery County

Photographer: Scott Madsen © 2016

9-27-16

Colorful, rounded slopes are typical of the Brushy Basin Member of the Jurassic-age Morrison Formation. Clayey bentonite beds in the Morrison often have a distinctive “popcorn” weathering texture resulting from expansion of the clay minerals when they get wet.