Earth Notes: Potash and the Petrified Forest

Oct 16, 2013

The Colorado Plateau is endowed with a world-class collection of geological eye candy, like the Technicolor badlands of Arizona's Petrified Forest. But conflicts arise when some of that geology is useful for more than a grand view.

Potash map of Arizona
Credit Arizona Geological Survey


Around 250 million years ago, huge lake beds lay where the Petrified Forest is now. When their water evaporated, it left behind huge deposits of potassium salts.

Today, we call those buried deposits "potash", a substance increasingly in-demand on world markets. That's because it's a much-needed crop fertilizer. The Arizona Geological Survey estimates that as much as 2 billion tons of it lie under 600 square miles east of Holbrook. A couple of companies are actively exploring the reserve's potential.

But, the biggest concentrations of potash are within, or just outside, Petrified Forest National Park. In 2004, Congress enlarged the park's boundaries by 125,000 acres.

Companies will not be mining within the old park boundaries. But, they have been buying underground mineral rights in the expansion lands, even as the park has been purchasing surface rights there.

If mining occurs, there are some environmental concerns. Deep mining brings the possibility of ground collapse; if solution mining is done, water use is a concern. The long-horizon views from the park's high points may be altered by an industrial presence.

The expansion lands have already been yielding exciting new paleontology and archaeology discoveries. But, how they will coexist with potential mining is a question that hasn't been answered yet.