DECKER, Mont. —
At Spring Creek Mine, a broad black seam of coal, reaching depths of 80 feet, runs like a subterranean river through arid, sagebrush-covered hills.
This is a world-class seam formed from the remnants of ferns, grasses and other plants that flourished here more than 50 million years ago, when this part of Montana was a humid marsh.
Read the full story here.