Chemicals in dripping water form records of ancient fires in speleothem cave structures
Jay Alder/Oregon State University
In the event of a fire, escape to the cave. This is the official emergency policy for Oregon Caves National Monument and Preserve, a forested area that protects a labyrinth of passages dissolved in a rare marble formation in the Siskiyou Mountains. There has been no fire in the cannery in the century. But the possibility of a conflagration in the dry forest is obvious. If a fast-moving fire broke out, the cave would be the safest place for park rangers to hide.
However, the 1.7-million-year-old cave is not completely insulated from surface fires. When a fire burns overhead, the heat and smoke can change the chemistry of the water that seeps down the bedrock. As it drips into the cave, it can leave traces of fire in the bare layers of mineral debris. Over the millennia, it forms inside strange cave structures known as speleothems, which protrude from every surface where water flows, including stalagmites on the cave floor and stalactites on the ceiling.
“It’s a picture” Katie WendtOregon State University paleoclimatologist, told me when I joined him on a recent cave expedition. He is among a group of researchers who are using fire cave records to trace fire activity back hundreds of thousands of years to a time when Earth’s temperatures were warmer than today. That, at the same time…
