It's known as "Black Sunday," the day when Exxon pulled out of western Colorado and the boom in oil shale turned to bust.

That was more than 35 years ago, but it's still an important event in the oil-rich areas of Mesa and Garfield counties.

Heather Abel first learned about the bust when she wrote for High Country News in the 1990s. It stuck with her -- and propelled her to write her first novel, "The Optimistic Decade."