Researchers Probe Fossilized Rain Forest

In this photo released Monday, April 23, 2007 by the Illinois State Geological Survey shows a fossil, part of a fossilized rain forest discovered in coal mines in Vermilion County in east central Illinois. Geologists say the area dates to the Pennsylvania Age, 300 million years ago. Researchers are probing the fossilized area which covers about 15 square miles, all more than 200 feet below ground, and is probably the largest intact rain forest from that period ever studied. (AP Photo/Illinois State Geological Survey) (AP)

-- Standing on the wind-swept flatlands of southern Vermilion County, you might think you'd have to drive the 180 miles to Chicago's Field Museum to find the nearest fossilized tree trunk from the Pennsylvania Age, 300 million years ago. Nah, just drill straight down.

That's where coal miners working south and west of Georgetown have unearthed, chunk by fossilized chunk, what has revealed itself over the past few years to be the remains of a fossilized rain forest.

It covers about 15 square miles, all more than 200 feet below ground, and probably is the largest intact rain forest from that period ever studied, according to Scott Elrick of the Illinois State Geological Survey.

It's that scale that makes what lies just above the Riola and Vermilion Grove mines significant, he said.

"We never encountered one whole forest preserved in one shot like this," Elrick said Monday. "The fossils just didn't stop."

It's common to find small pockets of fossilized plants just above coal mines, he said. But in this case, experts believe, a fault that runs through the area unleashed a major earthquake that quickly sank the forest beneath a deep layer of mud, preserving it.

"What they're looking at is very rapid preservation of this forest," meaning that plant tissue was preserved in great detail, rather than being broken down over time, said Ian Glasspaul, a collections manager at the Field Museum who is not involved with the work in Vermilion County.

"It's a snapshot in time," he said. "That's what makes it exciting."

Elrick and researchers from the Smithsonian Institution and the University of Bristol in Great Britain started working in the mines a few years ago, driving deep underground in armored vehicles and then walking along miles of 7-foot-high passages.

They spent most of their time looking up, according to Howard Falcon-Lang, the scientist from the University of Bristol.

That's because the coal that's being mined used to be the soil that the ferns, mosses and trees of the rain forest grew on, he said in a Monday e-mail sent to The Associated Press.

Coal seams found across the United States, the United Kingdom and Europe once were the soil beneath the first rain forests, he said.