Stalagmite Contributes to Science

Stalagmite Contributes to Science
Underground Adventures Assists in Global Climate Change Research

Sierra Nevada Recreation Corporation’s (SNRC's) founder, Stephen Fairchild, crouches low in a dark underground chamber, and takes a reciprocating saw to an ancient stalagmite in Black Chasm Cavern. Carefully removing the crystalline cone, thought to have been approximately 20,000 years in the making, Fairchild carefully hands it over to UC Davis doctoral student, Jessica Oster.

This may seem like an odd action for a man who has devoted his life to the stewardship of underground environments by carefully and responsibly opening several caves for the education and enjoyment of the general public. In fact, this is the first time in his 30-year career he has ever permitted it to happen. A scientist at heart himself, Fairchild could not ignore the potential windfall of information his beloved caverns could provide.

“Caves are essentially like big, natural time capsules, slowly recording many things about their surroundings, including climate changes,” he explains. “Data taken from caves of the west coast will produce interesting and valuable climate signals. What we get from the climate record on the west coast is pure weather from the Pacific Ocean which hasn’t been modified by traveling over land masses. Since these mountains contain areas of limestone that often contain caves, we can get a sampling of weather not just over the ages but eventually maybe over the full north to south latitudes. This could give the most complete and accurate picture of weather changes ever produced.”

Speleothems (stalactites and stalagmites) in limestone caves are created by the deposition of calcite which separates from mineral rich water as it drips, flows, seeps or splashes into a cave. Each deposit creates a new layer, varying in size and chemistry based on the weather conditions above ground, which affects the mineral content and flow of water in the cave. Over time, these layers form into characteristic shapes. Stalagmites, such as the one removed by Fairchild, are created by water dripping from the ceiling of a cave, making a stone mound or cone shape on the floor. These particular formations are ideally suited to determining the climate record over geologic time, forming isotopic rings that can be read like the rings in a tree trunk.

Slices will be taken from the stalagmite and examined over the coming months at U.C. Davis, Berkeley Geochronology Center and the Lawrence Livermore National Laboratory. In her research, Oster is using uranium series dating, which, unlike radio carbon dating (which is only reliable as far back as 50,000 years) has the potential to provide climate data for 500,000 years.

Using core samples taken from another of SNRC’s properties: Moaning cavern in Vallecito, Oster has already discovered evidence of the Younger Dryas cold event, which is known to have taken place between about 12,500 and 11,000 years ago. Oster says, “This proves that Moaning Cavern formations can be a reliable recorder of climate change. I am expecting the Black Chasm speleothem to be equally reliable.”

The potential for this method means that precise dates for specific climate changes over thousands of years can probably be obtained. This will contribute significantly to the new body of terrestrial knowledge when combined with results obtained from caves in South America, Europe and Asia, creating the most accurate, global paleoclimate models ever obtained. This can only enhance our understanding of regional and global warming and cooling, thereby helping us to create more accurate climate models today and better prepare for the future.

Oster’s research will contribute to several scientific fields; based on some intriguing preliminary data, strontium isotopes, which demonstrate changes in Interactions with soil and limestone bedrock before the water gets into the cave, show distinct, identifiable signatures at Moaning Cavern. This means that there may be more oscillation in isotopes between a cave and its earth environment than expected from current scientific understanding.

Fairchild says: “It’s not yet fully understood how a cave exactly interacts with its environment - and Jessica’s research will contribute to the fields of cave chemistry and hydrology. This is important information for the caving community to have, especially as we strive to protect these ancient environments.”

As for Oster, she expects the caverns’ formation samples to continue to provide her with continuous research materials for many years.

Fairchild is happy to contribute to the field of science, but says it would be nice if the stalagmite could be replaced. To that end, Oster is taking the speleothem to UC Davis’ paleontology lab where it will be placed on a pedestal and scanned by lasers. The data collected by these lasers will create a 3-D computer model which is sent to a special printer. Layers of glue shot into powder recreate the solid object from its 3-D data. It sounds like pure science fiction, but the hope is that the stalagmite will be accurately reproduced and can be fixed onto its stump in Black Chasm Cavern. Visitors to this beautiful show cave will not notice a difference, and the formation could actually become part of the living cave if dripping water starts to deposit calcite on top.