Chemicals in drip water form record of ancient fires in cave structures
Jay Alder/Oregon State University
When a forest fire breaks out, I run into a cave. This is the official emergency policy of Oregon Caves National Monument and Preserve, a forested area that protects a labyrinth of passageways woven into rare marble formations high in the Siskiyou Mountains. The reserve hasn’t had a fire in a century. However, the potential for fires to occur in dry forests is clear. If a fast-moving wildfire were to burn out, the cave would be the safest hiding place for park rangers.
But the 1.7-million-year-old cave is not completely isolated from the fires burning on the surface. When a fire burns above, the heat and smoke can change the chemistry of the water that seeps through the rock. When it drips into a cave, it can leave traces of fire in a thick layer of mineral residue. Over thousands of years, this has accumulated in strange cave structures known as stalactites, which protrude from any surface through which water flows, including stalagmites on the cave floor and stalactites on the ceiling.
“It’s a snapshot.” katie wendtShe, a paleoclimatologist at Oregon State University, told me when I recently joined her on a caving expedition. She is one of several researchers using cave records of wildfires to extend the view of fire activity hundreds of thousands of years ago, when global temperatures were even warmer than today. This time…
Source: www.newscientist.com
