The biggest surprise to emerge from an archaeological survey that started late this fall in Sherburne National Wildlife Refuge near Zimmerman is what hasn't turned up.

A site such as this — land where Native Americans once hunted bison and elk, where the St. Francis River provided prime campsites, where Europeans once farmed — holds promise. There's potential to find evidence of Native American cultures, of fur traders and farmers.

"We've been in some terraces like this that jut right into the watershed and the river runs right by it and it's flat, and if you were ever in a canoe and wanted to just chill out for a while, that's where you would go," said Joe McFarlane, project manager and owner of St. Paul-based McFarlane Consulting.

But so far, they've found almost nothing.

On the day after Thanksgiving, with the St. Francis River providing a shimmery, sunlit backdrop, McFarlane dug shovel test pits with Jim Cummings, principal investigator, and Jacob Fritz, who is pursuing a master's in cultural resources management at St. Cloud State University.

The survey, which is to wrap up in May at a cost of no more than $76,850, is one element of a $520,000, 968-acre oak savanna restoration.

By the time the ground froze in early December, the McFarlane Consulting crew had surveyed about one-fifth of the 2,145-acre project. After 354 shovel tests and initial walking surveys, they'd turned up two prehistoric and two historic sites.

Work will resume in the spring, earlier if there's a thaw.

"Central Minnesota has a lot of earthen burial mounds that have been found over the last 100 years," said James Myster, the U.S. Fish & Wildlife Service's Bloomington-based regional archaeologist and historic preservation officer. "If they've identified any of those, we're going to put a buffer around them and completely avoid them during the timber sale."

Myster said FWS is also interested in prehistoric campsites or 100-plus-year-old farm sites.

What's there? What's not?

In an average year, the eight-state region handles 10 archaeology projects. Sherburne's is among the largest.

It started with pedestrian surveys. Walking 10 meters apart, the crew scanned the earth for visible features such as burial mounds. McFarlane estimated each of the five tracts surveyed turned up 20 to 30 spots worth a second look. They marked those with a GPS and later returned with a shovel.

On this day in late November, the pointed shovel sliced easily into the sandy soil. While bits of tangled roots turned up in the screen, barely a pebble was found in the fine, reddish-brown earth.

"It's like a presence/absence kind of thing," Cummings said. "That evidence is arrow points, spear points, pieces of ceramic pots. It might be the flakes from the manufacture of stone tools."

A report goes to the FWS and the Minnesota State Historic Preservation Office.

So far, there's not much to tell.

"We're surprised that we're not finding more cultural material. However, I'm confident that we will. We just haven't found that specific location," Cummings said.

One reason the crew expects to find more has to do with watersheds and biomes.

The state's watersheds drain to the Arctic, the Atlantic or the Gulf of Mexico — so anyone who followed those streams would have turned up here. Three biomes — prairies, hardwoods and pines — meet in Minnesota.

"Only Minnesota has appreciable amounts of all three. That's really significant. That's why people come here to hunt, camp, fish, recreate. That's also why people came here to hunt, fish, camp, survive," Cummings said.

"The excitement of it for me — and that's part of why I like to do archaeology — is connecting the landscape where we are to what it is we're finding or not finding," he said.