YOSEMITE NATIONAL PARK, Calif. (AP) — It could take months for investigators to determine what ignited the wildfire that has consumed more than 370 square miles of forest in and around Yosemite National Park, officials said.
The fire was 80 percent contained Wednesday. But crews don't expect full containment before Sept. 20 because the portion of the fire burning inside the park is headed toward granite outcroppings that will act as a natural firebreak but won't be classified as technical containment.
Letting geological formations help will allow firefighters to focus some efforts inside the fire's footprint. Jerry Snyder of the U.S. Forest Service said they have begun to cut breaks and start backfires in an effort to save grazing land, wildlife habitat and historic buildings left over from early timber camps.
Investigators have ruled out an illegal marijuana grow as a potential cause, ending speculation by a local fire chief that the gardens that plague federal land could be to blame.
The steep and inaccessible canyon where the Rim Fire started Aug. 17 in the Stanislaus National Forest doesn't have a water source that growers look for when they set up remote gardens, Snyder said.
"The lead investigator says there's no evidence of any type of grow in the area where the fire started," Snyder said.
Snyder also said lightning isn't to blame. Investigators will weigh a number of factors before they make a final determination about what sparked the blaze, he said.
"They'll be able to tell whether there was an illegal campfire in there," he said. "Another thing to consider is that this area is very steep, and if there was a rockslide two rocks hitting together could make a spark to ignite dry brush."
Officials said 111 structures, including 11 homes, have been destroyed. More than 4,300 firefighters are still battling the blaze.
