Happy Earth Day, everyone!

Sandstone Mountain, Red Cliffs Desert Reserve, Washington County, Utah
Photographer: Tyler Knudsen; © 2012

Shifting sands partially bury an unusually large (about 1 foot in diameter) spherical hematite concretion that has eroded from the nearby Jurassic-age Navajo Sandstone. The concretion’s dark concentric bands formed when iron-oxide minerals precipitated out of groundwater that flowed through the sandstone.