An anonymous reader writes "It's been 25 years since the Exxon Valdez dumped 11 million gallons of crude oil in Prince William Sound, and you can still find oil sticking to rocks. Worse yet, scientists say the oil could be around for decades yet to come. From the article: 'There are two main reasons why there's still oil on some of the beaches of the Kenai Fjords and Katmai National Parks and Preserves in the Gulf of Alaska, explains Gail Irvine, a marine ecologist with the U.S. Geological Survey and lead researcher on the study. When the oil first spilled from the tanker, it mixed with the seawater and formed an emulsion that turned it into a goopy compound, she says. "When oil forms into the foam, the outside is weathering, but the inside isn't," Irvine explains. It's like mayonnaise left out on the counter. The surface will crust over, but the inside of the clump still looks like mayonnaise, she explains.'"