The invisible conflagration was only evident in the columns of coal-scented smoke rising from metal pipes drilled into the earth. They were placed on this remote public land as part of an effort to learn more about and maybe gain the upper hand on one of the coal seam fires currently burning under an estimated 75 acres across Colorado.
A new report from the Colorado Division of Minerals and Geology catalogues each of the 32 fires, ranks their danger and points up their fickle and volatile natures.
These fires _ some of which have been burning for more than a century _ can be simple curiosities that melt snow, belch smoke and crisp cheat grass. At their worst they can flare with little or no warning and spark wildfires, as happened with a 2002 fire that burned 20,000 acres and 29 homes near Glenwood Springs.
They can also open unstable fissures in the ground, or emit noxious gasses _ problems that are being magnified as more people move into once remote coal-mining areas.
The report, the first comprehensive study of these fires in 17 years, shows that some coal fires, like this one on Skull Creek, have a higher potential to cause problems.
''They're all different,'' said the report's author, geologist Steve Renner with the division's Abandoned Mine Lands program.
Renner describes the underground fires as sort of living, breathing monsters that inhale and exhale air through surface cracks and old mine shafts.
Efforts to put out coal seam fires _ piling enough dirt on top to cut off oxygen, injecting grout into seams to isolate them, and flooding the burning fissures with water _ have largely failed.
But now that he has them identified, Renner is searching for better and more cost-effective ways to tame some of the fires.
That mission has brought him down a barely passable muddy road and up this outcrop to drill a checkerboard of holes into a fire that has been burning underground for at least four decades.
Unsuccessful attempts were made in the 1960s to put it out by digging part of the coal seam up and dumping dirt on it.
This time Renner is pumping foam into the depths of a fire that he has pinpointed with satellite coordinates, aerial infrared imaging and digital temperature measures.
''It's like a big science fair kind of thing,'' he said as he and his drilling contractors injected vent pipes with the same foam used to extinguish the smoldering rubble of the World Trade Center in the aftermath of the Sept. 11, 2001, terrorist attacks.
The new foaming agents and saline injections work better than older methods, but are often too expensive for an abandoned mine program that has a total annual budget of just over $2 million and faces a budget hit. A federal coal mining fee that helps to fund the abandoned mine program expires in June and may not be reauthorized.
Loretta Pineda, a spokesperson for the division, said the lack of resources has some residents riled.
''We get a lot of concern from landowners asking 'why can't you put these fires out?,''' Pineda said.
Renner hopes to quench some of those concerns by disseminating the 89-page report to private landowners, local governments, land management agencies and fire departments so they will know what the potential is for surface problems. He said he hopes some of those entities will partner with his agency to take on containment and monitoring measures.
At the top of that list, is the most complicated underground fire in Colorado _ the century-old blaze not far from I-70 in South Canyon that touched off the 2002 Coal Seam Fire. That fire, which led to the evacuation of 3,000 residents, gave urgency to Renner's report that was then in the planning stages.
Renner and the city of Glenwood Springs will work together on containment measures for that fire.
Renner also has plans this year to partner on containment work on fires at Mesa Verde National Park, and near Grand Junction, Crested Butte, Trinidad and Somerset.
