Matt Forir surveys the main cavern of Riverbluff Cave, a veritable time capsule of Ice Age fossils, discovered on Sept. 11, 2001. Fossils found in the Springfield-area cave are believed to be almost 1 million years old, making it perhaps the oldest Ice Age cave in North America.

For most Americans, Sept. 11, 2001, is a day of infamy. Matt Forir remembers it as the day his life changed forever. A chance discovery of a surprising treasure beneath the surface of Greene County that day would become the focus of his professional life.

That fall, Matt was a graduate student in geology at Southwest Missouri State University (now Missouri State University). A protégé of the late Professor Ken Thomson, one of Missouri’s preeminent experts on karst geology, Matt often was asked to investigate newly discovered caves in southwest Missouri.

Such a call came on this fateful day. A construction crew working on Cox Road in Springfield fired off a small explosive charge placed before a nationwide halt to blasting was ordered. The blast uncovered a large cavern in the earth below. Immediately, work stopped and cave experts were summoned. Frankly, Matt says, it was not an assignment he welcomed.

“I was glued to the TV,” Matt says, recalling how he, like most Americans, watched the news of terrorist attacks. “The phone rings and it was Ken Thomson saying this new cave opened up. I wasn’t interested. I was focused on the TV.”

But what Matt and his caving partner, Lisa McCann, saw when they entered the cave would forever change the way they remember Sept. 11. It would also rewrite scientific understanding of the Ice Age and add greatly to the natural history resources of Missouri.

Nicole Forir displays a prehistoric turtle shell for field house visitors Katherine Nichols and her children Ayden and Kira.

Riverbluff Cave, as the underground time capsule became known, is perhaps the oldest Ice Age cave ever discovered in North America. More than 2,000 feet long, it features a cavernous main room with impressive formations. Fossilized material found inside has been dated to 970,000 B.C. Sealed for tens of thousands of years, humans had never visited the cave. Instead, its mud walls and floors bear evidence of animal inhabitants long extinct.

“The first thing we found was a claw mark on the wall,” Matt recalls. “It was not just a claw mark. This thing is 8 inches wide, 2 feet long. It was 12 to 14 feet off the ground.”

Matt immediately recognized the signs of a prehistoric giant short-faced bear. Extinct for 10,000 years, the creature was the largest bear ever to inhabit North America. Twice the size of modern grizzly bears, the giant short-faced bear is believed to have weighed nearly a ton, on average.

“We see those guys in caves miles back from entrances, going through areas that we can barely go through,” says Matt, a paleontologist who has studied and unearthed fossils across America. “They were the first cavers.”

Another set of claw marks appeared to have been made by a large cat, possibly a saber-tooth tiger, but more likely the larger and less common American lion. Intact fossil remains of small rodents, snakes and other creatures littered the cave floor.

“We realized that we had stumbled onto something phenomenal,” says Dave Coonrod, presiding commissioner of Greene County, who also visited the site on Sept. 11.

Discovered the day humans first entered Riverbluff Cave, these claw marks 14 feet up a mud wall are believed to have been made by a giant short-faced bear, the largest bear ever to inhabit North America.

Coonrod, who holds a degree in environmental geology, knew right away that the cave was a valuable scientific resource. Plans for the road were redrawn and the cave entrance was resealed as each day outside air entered the cave put scientific evidence at risk. It was March 2002 before another human entered Riverbluff Cave.

In the intervening years, discoveries inside the cave continued to amaze Matt — now a Greene County employee, charged with exploration and investigation of the cave — and others who entered it. The cave contained remains of a previously unknown millipede, and fossilized dung provided clues to the short-faced bear’s diet. Bones from a mammoth (and possibly its unborn calf) found inside the cave probably washed in from the surface, but their location in a soil layer 660,000 years old challenges previous scientific assumptions.

One of the most startling finds was a cluster of footprints made by prehistoric swine called peccary. Previously, paleontologists thought peccary bones in caves were left there by predators dragging a meal to safety. The hundreds of footprints in Riverbluff Cave proved that theory wrong.

The still soft clay of Riverbluff Cave brings prehistory to life in a way that ordinary fossils embedded in layers of rock never can, Matt says. “In the cave, you’ve got a claw mark. An animal walks in there and makes a slash mark that records a split second of time 100,000 years ago. That’s unique.”

Matt’s wife, Nicole, joined the cave exploration team as a volunteer in 2005 and now serves as operations director for Riverbluff Cave. She shares her imaginations of prehistoric wildlife encounters with visitors to the cave’s field house, where artifacts are on display.

The foot bone of a peccary found in Riverbluff Cave bears a bite mark, leading to speculation the pig was attacked by a bear.

“You can see the footprints of the peccary in the cave, but there’s this one area where you can see them running up a wall,” she says. “It’s almost like they’re trying to get away from something. You can almost put together a little story that they were trying to get away from a bear. That’s really neat to be able to personalize these animals.”

Evidence of large mammals attracts widespread attention around Springfield, but scientists are just as interested in small discoveries. Examination of soil samples and micro-fossils provide clues to the cave’s age and previously unknown details about life during Earth’s last Ice Age, a roughly 1 million-year period geologists call the Pleistocene epoch.

The Ice Age ended about 12,000 years ago, but Matt suspected that Riverbluff Cave preserved a much earlier time.

The first verification of his theory came when carbon dating — which accurately dates artifacts as old as 55,000 years — failed to detect any carbon traces. Examination of the iron ore contained in the cave’s miry clay showed a “magnetic anomaly.” The north-south polarity of the molecules was reversed — a sign that the material predates the last reversal of the Earth’s poles, some 780,000 years ago. Other dating techniques suggest the cave is nearly 1 million years old.

Research at the cave is supported by Greene County, which employs Matt and owns the land above the cave, and the Missouri Institute of Natural Science. The fledgling non-profit group, which employs Matt’s wife, exists to one day establish the first statewide natural history museum. Already plans are in place for construction of a 5,000-square-foot museum building to begin early in 2008.

In the meantime, word of the cave’s discoveries is spread at the field house and through a unique high-tech capability of the cave. Riverbluff Cave is believed to be the first and only cave on the planet with a fiber-optic connection. Interactive technology allows classrooms across the globe to participate in distance learning presentations conducted live from the cave’s depths.

Matt Forir poses with a replica skull of a giant short-faced bear, as well as a piece of cave formation, a prehistoric turtle shell and a mammoth bone. These items, along with fossils from around the world, are on display at Riverbluff Cave’s field house.

The largest such subterranean educational encounter occurred on Nov. 7, when 3,000 students in six states tuned in as Matt broadcast over the Internet from the cave’s main cavern.

For now, such events provide the only public access to the cave. The fossils and other scientific evidence inside are simply too valuable to risk damage. Already, the cave has suffered as vandals broke in, carved their initials in formations, crushed snake skeletons and trampled on claw marks — an act that earned the perpetrators three-year prison sentences.

Instead, Internet-based technology fulfills the vision Greene County officials had for Riverbluff Cave as they made the decision to protect the newfound resource.

“One of the main reasons we are so keen on this is it’s a great educational venue for youth,” says Presiding Commissioner Coonrod. “We saw it as a natural resource that we believed would be of value to the public and of great interest to the citizens we serve.”

Sharing that resource with the citizens of Missouri, not to mention the world’s scientific community, is Matt’s mission. The work he and others are doing below the surface of Greene County will add greatly to knowledge of prehistory and expand our understanding of the last Ice Age.

“We’re rewriting what we know about the Ice Age in the Midwest,” he says. “We have one-of-a-kind fossils. We have new species. We’ve got remains in that cave that exist nowhere else in the world.”

Riverbluff Cave is not open to the public. For more information log onto www.riverbluffcave.com, or call 417-883-0594. Visit the field house at 2327 W. Farm Road 190 in Springfield, Monday through Friday, from 10 a.m. to 4 p.m.