Cliff palaces in Mesa Verde National Park. Image by Ken Lund via Flickr

In the hot middle of August 1996, lightning struck a dense piñon-juniper range in Mesa Verde National Park, Colorado. Then flames licked up, burning northward through Soda Canyon, Little Soda Canyon, and Park Mesa’s research area. The blaze ran its course for seven days. Aircrafts doused the park in water, and fire retardants known as “slurry” were used to snub out flames in the nooks of tough-to-reach craggy topography. Slurry stains are still visible, almost 20 years later, on the impressionable sandstone trail to Spruce Tree House, a collection of cliff dwellings. The national park contains an estimated 600 buildings fashioned into cliff alcoves, and over 5,000 other archeological sites produced by the Ancestral Puebloans. Although the fire quit just before reaching the Visitors’ Center, burning through a small (but important) 4,781 acres in the end, it accelerated a natural process known as spalling. When water evaporates in sandstone, layers of rock flake off. Because of this accelerated spalling, the fire claimed an important victim—the famous Battleship Rock Panel, which was degraded and destroyed. This petroglyph panel portrayed humans and animals, dated roughly back to 1100 AD, was chiseled into the sandstone, and helped archaeologists contextualize life of the Ancestral Puebloans.