TOWOAC, Colo. (AP) -- A wildfire that doubled in size in one hour was threatening ''world-class'' archaeological sites on tribal land Tuesday in southwestern Colorado.
Crews attacked the blaze on the Ute Mountain Ute Indian reservation mainly from the air to avoid damaging any fragile artifacts with bulldozers.
''World-class archaeological resources are threatened,'' said Tom Rice, director of the tribe's environmental department.
''That area is extremely rich in prehistoric cultural resources, including Anasazi sites that date from the Puebloan period. We're very pleased with the amount of effort that's trying to protect these valued resources,'' he said.
The blaze, named the Dwelling Fire, grew from 150 acres to 300 acres Monday and was uncontained.
It was burning about five miles south of Mancos and within five miles of a second, 2,518-acre blaze near Mesa Verde National Park, also on Ute Mountain Ute tribal land.
The larger fire, sparked by lightning Thursday, was 50 percent contained.
A total of 408 firefighters and eight helicopters were working on both fires. Archaeologists were on hand to help preserve artifacts.
Crews faced 90-plus-degree temperatures and gusty winds this week, and the heat showed no sign of relenting.
Although no buildings were threatened by the two fires, the Ute Mountain Ute tribe's business could be affected because tours are one of its main sources of income, said Jen Chase, spokeswoman for the federal fire managers.
Ute Mountain Ute Tribal Park covers more than twice the acreage of nearby Mesa Verde. Pottery shards, corn cobs and grinding stones are scattered on the grounds, which are accessible only by prior arrangement with Ute Mountain Ute guides.
The Dwelling Fire was burning in pinon juniper, mountain shrub and sage and other perennial grasses. Larry Trapp, deputy incident commander with the Rocky Mountain Incident Management Team, likened the burning vegetation to a dried, crumpled newspaper on fire.
Chase said the cause of the fire was under investigation.
Officials reduced the estimated size of the larger fire from 2,800 acres to 2,518 acres after further mapping, said Larry Helmerick, a spokesman for the Rocky Mountain Area Coordination Center.
A fire near Norwood, also in southwestern Colorado, grew from 250 to 500 acres Monday, but firefighters said it also was 50 percent contained. Three homes previously considered threatened were no longer in danger.
The fire was started by lightning on Friday.
More than 70 firefighters and two helicopter were on the lines.
Four other Colorado blazes totaling about 4,400 acres were considered ''ecological restoration'' fires benefiting the environment.