POTD January 17, 2014: Chalk Knolls, Tule Valley, Millard County, Utah

Chalk Knolls, Tule Valley, Millard County, Utah
Stefan Kirby

Stromatolites, precipitated by algae in reef-like columns, are common in the Cambrian-age Hellnmaria Member of the Notch Peak Formation, Chalk Knolls, Tule Valley, Millard County