PURPLE SPRINGS, Alta. - Buried deep below a shallow southeastern Alberta valley, punctuated by wind-swept sand dunes, vast grassland and aging cow manure, lies evidence of a slaughter that took place 2,500 years ago.
What was once little more than leased Crown land now doubles as a precious archeological dig, which, with each turn of the trowel, is teaching University of Lethbridge researchers what one of Alberta's few known bison kill sites can tell us about our past.
Listening to archeology professor Shawn Bubel tell the story of how a roaming herd met its demise, it's as though she was there when the nomadic hunters stalked, slaughtered and butchered their prey in a single winter kill.
"From what we can tell, the hunters followed the bison into this valley, scattered around the dune and ambushed them," she says, while her team of 14 students meticulously picks away at the dirt.
"They slaughtered about 10, maybe 15, cut them open, ripped them apart for food, chopped their legs off, ripped the ribs open to get the meat, tore the hide off and the bones fell all around here.
"Then they took what they needed, what they could carry and continued on to their camp, which is probably about four kilometres that way, to the Oldman River," says Ms. Bubel.
"That's what we think so far. But we are a long way from completing the picture."
Over the past three years, researchers have spent a total of five months excavating the site.
The bone bed at this relatively secret location near Purple Springs, about 220 kilometres southeast of Calgary, was first discovered by professionals in 2003, when Ms. Bubel, president of the Archaeological Society of Alberta, learned that a local man was desecrating the area. The man dug up bones on his own, and later recruited his children to help, Ms. Bubel says.
Angry archeologists nicknamed him the "pot hunter."
He and his family were spotted carting shovels and pick axes into the area, unearthing artifacts and removing them without a permit -- an act that has been illegal in Alberta since 1973.
Although no charges were laid, prosecution carries a fine of up to $50,000 and/or one year in prison.
Once RCMP and Alberta government officials were notified, Ms. Bubel was sent to the site to investigate the extent of damage and to map the land. On that first visit, she discovered evidence that assured her the area was potentially a bison kill site.
The first dig began in May 2004. By September, radio carbon dating determined the artifacts were 2,500 years old.
On May 1 of this year, after a hiatus from the dig in 2005, a University of Lethbridge crew returned to the Fincastle Kill Site, so named because it's located on the hamlet of Fincastle grazing reserve.
They have spent the past month sifting through two areas, each smaller than the previous dig.
It's a finicky field study, the students say, although rewarding.
At this dig, seven teams of two work in roped-off sections, one-metre square, for up to 10 hours a day.
One student squats on the ground and gently searches five-centimetre deep layers, uncovering leg bones, ankles, tails, vertebrae, toes, intact jaws and teeth of bison young and old.
The student also finds the weapons used to kill them, plus fire-broken rock used to boil water.
A second student records the data.
The team will keep digging down until the soil meets clay.
Once the five-centimetre layer has been removed, the dirt is then sifted. Students collect pieces smaller than a toddler's tooth and file them away in plain brown envelopes.
So far, the researchers have found nearly 7,000 clues left behind by the hunters.
Ms. Bubel says less than 5% of the site has been studied. But the work doesn't end with the excavation.
Indeed, it's just beginning.
That's where Ang Watts, the "bone collector," comes in.
The 26-year-old master's student identifies and catalogues all the recovered bone, fragments and flakes in a lab at the University of Lethbridge, once they are cleaned.
"We're finding a lot of legs, long bones," she says. "On many of them, we can tell that they have been fractured by humans. They have patterns where we know they have been smashed through."
It's Rena Varsakis's job to study the spears, darts and arrows used to slay the animals.
She's determined that 85% of the projectile points are fashioned from Knife River flint, a glassy quartz material that originates in what is now North and South Dakota.
"We know the tools were brought here because they don't fit with the archeological history of Alberta," says Ms. Varsakis, a graduate student.
"Every day is exciting, trying to figure out our prehistoric history, making a real contribution to understanding this time period, so that we know more about the people who came before us."
Ms. Bubel estimates it will be at least four years before the entire collection will reach its final destination at the Royal Alberta Museum in Edmonton.
If another permit is granted, the dig will resume next May.
The professor and her students feel uneasy about leaving the site for another year, given the number of people who know where the dig is but don't appreciate the historic value.
"We care about this place. We dig with precision, and painstakingly preserve every artifact," Ms. Bubel says. "But looters come in here with shovels and disturb the place. It's sickening."
Taber RCMP say two men considered suspects in the illegal digging in 2003 and 2004 have not been charged, and the investigation was closed after they agreed to return the stolen property to the Archaeological Society of Alberta.
"The looting has stopped," says RCMP Sgt. Chris Griffin.
"With the advice of Crown counsel, we gave the men the benefit of the doubt and explained the severity of what they were doing."
Sgt. Griffin says concerns by the students regarding leaving the site unattended for a year are warranted.
"It's a Catch-22 because on one hand, it's such an important find, you want people to know about it, but when we talk about it, we invite the unscrupulous kind to wander in and search," he says.
"We might as well put up a sign saying, 'Hey, we have something hot here, come look.' And we don't have the resources to sit there 24 hours a day."