CHARLESTON, W.Va. -- An Ohio University research team analyzing the growth layers of a stalagmite from a Greenbrier County cave has produced what it believes to be the most detailed geological record to date on climate cycles in eastern North America over the past 7,000 years.

Among other conclusions, the new study confirms that during periods when Earth received less solar radiation, the Atlantic Ocean cooled, icebergs increased and precipitation decreased, creating a series of droughts, some more than a century long.

The stalagmite that is the focus of the study is a 7,000-year-old, 8-inch long specimen from Buckeye Creek Cave near Williamsburg.

"Caves are some of the very few places on Earth where the climate can be recorded in a meaningful way," said Ohio University geologist Gregory Springer, who led the research team. "Stalagmites are protected from the weather, grow over long periods of time, and are well-preserved."

Other regional climate cycle studies have made use of data found in the sediment of Appalachian lakes, but fish and other aquatic creatures have muddied the geological record at such sites, according to study co-author Harold Rowe, an assistant professor of geological sciences at the University of Texas at Arlington.

But caves, Rowe said, "haven't been disturbed by anything. We can see what happened on the scale of a few decades. In lakes of the Appalachian region, you're looking more at the scale of a millennium."

Researchers chose to use a stalagmite from Greenbrier County because Buckeye Creek Cave "lies along the jet stream in an area where the climate is influenced by the Gulf of Mexico, the Pacific Ocean and the Atlantic Ocean," Springer said. "It's found in a key little juncture where what's going on around the hemisphere is felt intimately there."

By examining the concentrations of the trace metal strontium and carbon and oxygen isotopes in the growth layers of the stalagmite, scientists are able to draw conclusions about climate conditions as brief as a few years. They also found evidence of at least seven major drought periods since the last ice age.

Strontium occurs naturally in the soil and is washed through limestone during periods of rain. During dry periods, strontium is concentrated in stalagmites, making them good indicators of drought. Carbon isotopes, also stored in stalagmites, can indicate drought because drier soils slow biological activity.

In their study, published online in the journal Geophysical Research Letters, Springer and other researchers cut and polished the stalagmite, examined the growth layers, and then used a drill to take 200 samples along its growth axis. The metals and isotopes found in the stalagmite were weighted and analyzed to determine their concentrations over time.

CHARLESTON, W.Va. -- An Ohio University research team analyzing the growth layers of a stalagmite from a Greenbrier County cave has produced what it believes to be the most detailed geological record to date on climate cycles in eastern North America over the past 7,000 years.

Among other conclusions, the new study confirms that during periods when Earth received less solar radiation, the Atlantic Ocean cooled, icebergs increased and precipitation decreased, creating a series of droughts, some more than a century long.

The stalagmite that is the focus of the study is a 7,000-year-old, 8-inch long specimen from Buckeye Creek Cave near Williamsburg.

"Caves are some of the very few places on Earth where the climate can be recorded in a meaningful way," said Ohio University geologist Gregory Springer, who led the research team. "Stalagmites are protected from the weather, grow over long periods of time, and are well-preserved."

Other regional climate cycle studies have made use of data found in the sediment of Appalachian lakes, but fish and other aquatic creatures have muddied the geological record at such sites, according to study co-author Harold Rowe, an assistant professor of geological sciences at the University of Texas at Arlington.

But caves, Rowe said, "haven't been disturbed by anything. We can see what happened on the scale of a few decades. In lakes of the Appalachian region, you're looking more at the scale of a millennium."

Researchers chose to use a stalagmite from Greenbrier County because Buckeye Creek Cave "lies along the jet stream in an area where the climate is influenced by the Gulf of Mexico, the Pacific Ocean and the Atlantic Ocean," Springer said. "It's found in a key little juncture where what's going on around the hemisphere is felt intimately there."

By examining the concentrations of the trace metal strontium and carbon and oxygen isotopes in the growth layers of the stalagmite, scientists are able to draw conclusions about climate conditions as brief as a few years. They also found evidence of at least seven major drought periods since the last ice age.

Strontium occurs naturally in the soil and is washed through limestone during periods of rain. During dry periods, strontium is concentrated in stalagmites, making them good indicators of drought. Carbon isotopes, also stored in stalagmites, can indicate drought because drier soils slow biological activity.

In their study, published online in the journal Geophysical Research Letters, Springer and other researchers cut and polished the stalagmite, examined the growth layers, and then used a drill to take 200 samples along its growth axis. The metals and isotopes found in the stalagmite were weighted and analyzed to determine their concentrations over time.

The study confirms a connection suggested by geologist Gerard Bond that weak solar activity, caused by fluctuations in the sun's magnetic fields occurring at intervals of about 1,500 years, cools the North Atlantic, creating more icebergs and ice rafting. According to the Ohio University study, such "bond events" occurred seven times during the past 7,000 years.

While modern records show that a cooling North Atlantic increases moisture and precipitation, during past millennia the tropical regions of the Atlantic also grew colder, creating a drier climate and prompting the series of droughts, according to the OU researchers.

The climate record revealed through the study of the Greenbrier County stalagmite suggests that North America could face a major drought event again in 500 to 1,000 years. But Springer said that human-produced global warming could offset the cycle.

"Global warming will leave things like this in the dust," he said. "The natural oscillations here are nothing like what we would expect to see with global warming."

Springer, a native of Paden City and a graduate of West Virginia University, said he has been interested in caves since childhood, and became an active caver while a student at WVU.

He has been using caves in West Virginia to study stream flow and prehistoric floods, in addition to climate change.

"We're working in multiple caves in Greenbrier County and one cave in Tucker County," he said.

A current research project involves stalagmites more than 300,000 years old.

Collaborators on the study also included Lawrence Edwards, Ben Hardt and Hai Cheng of the University of Minnesota.

Reach Rick Steelhammer at rsteelham...@wvgazette.com or 348-5169.