An archaeologist's dream is a clean slate of undeveloped land to explore and discover unwritten history. For me and three other archaeologists from the Minnesota Historical Society, that dream came true in the spring of 2010. Our assignment: Search for archaeological sites on 3,000 acres of land recently designated as Lake Vermilion State Park in northeastern Minnesota. We knew the fieldwork would be challenging yet rewarding on the rugged terrain with its bedrock ridges, wetlands, and five miles of Lake Vermilion shoreline.

Archaeological inventories or surveys are done in Minnesota state parks before the Department of Natural Resources builds campgrounds, picnic shelters, water accesses, and other facilities for visitors. Ground-disturbing construction can destroy archaeological sites and erase unwritten history forever. State and federal laws protect such cultural resources for future generations to learn from, appreciate, and enjoy.

Little was known about the history of the new property. U.S. Steel Corp. owned it for many years and had it logged to provide support timbers for nearby Soudan Mine. We researched historical accounts of Lake Vermilion, scrutinizing old maps and examining local histories. We met with Bois Forte Band of Chippewa elders, who told us their ancestors once had villages, gardens, cemeteries, campsites, and places for wild rice processing, maple sugaring, and fishing along the shore and islands of Lake Vermilion. But no one had found evidence of any of those sites within the boundaries of the new state park. Our pre-field research identified only one previously recorded archaeological site in the new state park: a location where a single stone tool had been found.

Natural Attractions.

Places on the landscape that people enjoy today are places that people have appreciated for thousands of years. Lakeshores, riverbanks, and high terrain with vistas were historically used for harvesting food, building shelters, holding ceremonies, and traveling. Because these landscape features occur in the park, we knew we were going to find archaeological sites. Other archaeologists had recorded 57 sites on Lake Vermilion, suggesting that the lake was home to many groups of people for thousands of years.

We began by doing surface examinations of moderate- to high-potential areas for archaeological sites. Using parallel transects spaced at 50 feet, we bushwhacked through the terrain. Compasses don't work well in iron country because of the rocks' strong magnetism, so we each carried a GPS unit to check our location as we scrambled through dense vegetation and across steep slopes.

In areas with exceptional potential and those proposed for park construction, we performed shovel tests. We excavated 18-inch-diameter holes down to glacial till or bedrock, usually 6 to 14 inches deep in the shallow soils of Lake Vermilion State Park. We then sifted the soil through quarter-inch screen to find and collect artifacts. We kept careful notes on provenience, or where artifacts were found. Using a GPS, we recorded the location of each cultural feature, surface artifact, and shovel test. We must be able to relocate sites so we can manage and protect those warranting preservation. By the end of 2013, we had discovered 18 archaeological sites.

Half of these sites are clusters of small iron-ore prospecting pits. Our surface inspection between 2010 and 2013 had surprised us by revealing the presence of more than 400 such pits. Prospectors dug the pits through the glacial till and took bedrock samples to test for ore content. Most of the pits were dug in 1880 during an expedition led by geologist Albert H. Chester. Hired by Charlemagne Tower Sr., the namesake of the Iron Range town of Tower, Chester discovered the site that became Soudan Mine, Minnesota's first, oldest, and deepest iron-ore mine. One of 25 national historic landmarks in Minnesota, it is now in Soudan Underground Mine State Park, next to Lake Vermilion State Park.

Microscopic Evidence.

We identified other archaeological sites indicating American Indian heritage. Several contained hand-dug pits about 4 feet wide and 1 or 2 feet deep. We were disappointed when shovel testing uncovered no artifacts near the pits. We continued our investigation by excavating a portion of one of the pits and still found no artifacts. We then took a cupful of soil from the bottom of the pit, hoping it would contain evidence of food storage. Scientists at the PaleoResearch Institute in Colorado examined the soil and found small silica bodies called phytoliths, which are found in various parts of plants. Each plant species can have phytoliths of different shapes and sizes. The lab discovered phytoliths of maize, or corn. This microscopic evidence solidified our interpretation that these were food storage pits.

Were Bois Forte Band members growing maize at or near this site? Was the maize harvested elsewhere and brought here for later use? We may never know. But we know from historical accounts that Bois Forte band members were growing maize in the late 1800s and that American Indian people in northern Minnesota and southern Canada have used maize for more than 1,000 years.

Ancient Quarry.

During our initial walkover of the Cable Bay shoreline and ridges, archaeologist LeRoy Gonsior noticed a large piece of gray chert sticking out of the ground. A sedimentary rock containing silica, chert can be chipped or flaked to form tools with sharp edges. Early people used chert to make tools such as projectile points, arrowheads, knives, drills, and scrapers. This piece of modified chert was the first American Indian artifact found during our park survey.

As we carefully combed the area, we found other chert fragments, ranging from gray to black in color, protruding from thick vegetation on a hillside. Large boulders of the chert were at the base of the slope. Our shovel tests turned up more chert flakes and tools. All of this confirmed that we had stumbled across an ancient chert quarry.

Here American Indian people mined and gathered chert for making stone tools. For years, archaeologists had seen artifacts made from this type of chert from many other sites around Lake Vermilion and in the Boundary Waters Canoe Area Wilderness, but no one knew its source until now. The quarry is the first evidence of mining activity in the area. Additional surveys nearby uncovered more archaeological sites, all having artifacts made from the gray to black chert from the Lake Vermilion Formation.

Surprise at Armstrong Bay.

While shovel testing an area on the lake's Armstrong Bay, the archaeological team discovered an exceptional American Indian campsite. Testing had revealed stone flakes and fire-cracked rocks along a terrace above the shoreline. To our surprise, one test contained four flakes made from obsidian, a black volcanic glass not native to Minnesota.

Obsidian naturally outcrops in and south of the Rocky Mountains. In North America, obsidian is one of the most highly prized types of stone that ancient people used to make tools. Our interest was piqued: Who was using this foreign stone for toolmaking? When and how did it get here?

To start finding answers, archaeologists Jim Cummings, Douglas George, and I re-examined the site in November 2010 just before the ground froze. We dug an excavation unit, 1 by 2 meters, next to the shovel test that yielded the obsidian. This opened an incredibly informative window into the past.

We did shovel skimming and troweling in 5-centimeter layers and then screened the soil through one-eighth-inch mesh to recover as many artifacts as possible. Because my fingers weren't working well in the frigid weather, I vividly remember using tweezers to retrieve hundreds of small flakes and burned bone fragments from the screen. Within the first 10 centimeters of soil, we found hundreds of stone flakes, stone tools, fire-cracked rock, and small pieces of burned bone. Most of the stone artifacts were made from local materials, including quartz, Hudson Bay Lowland chert, and Lake Vermilion Formation chert from our newly identified quarry. Other stone types not found locally included Knife River flint from western North Dakota and quartzite from eastern Wyoming.

With recovery of 155 obsidian artifacts, the Armstrong Bay site has yielded more obsidian than any other archaeological site in Minnesota. Each obsidian source has a unique chemical fingerprint, identifiable with a specialized X-ray florescence analysis. Our obsidian was sourced to a famous quarry called Obsidian Cliff in Yellowstone National Park in northwestern Wyoming. We don't know exactly how these exotic tool stones got to Lake Vermilion, but they must have arrived through trade via networks that crossed the continent hundreds of years ago.

Burned Soil.

At the 10-centimeter depth, we noticed bright orange soil. Having seen this oxidized soil at other sites, we knew it had been heated intensely and represented the remains of a campfire or hearth. The burned soil contained hundreds of very small burned bone fragments. Archaeologist David Mather examined them and could identify only two. One bone came from a bear paw, and the other was part of a beaver's vertebra. We sent the remaining fragments to a lab to find the age of the fire by radiocarbon dating. The date came back: 600 years old.

This date places the campsite's use in Late Woodland times. The people using the campsite were likely of Cree or Assiniboine ancestry. Bois Forte band members believe Ojibwe people moved into this region by the 1600s. This movement coincides with the Ojibwe migration story that tells of their journey from the Great Salt Sea (Atlantic Ocean) to the Great Lakes region. Bands eventually moved west, following rivers to the Lake Vermilion region.

The story, as seen through the window of our excavation unit, is not quite done. Under the hearth, we found a stone projectile point. Its size, side notching, and grinding on the base suggest a date between 5,000 and 7,000 years old, Middle Archaic times. The point probably was hafted to a spear or dart shaft and used for hunting. This find suggests the site has at least two occupation periods—Middle Archaic and Late Woodland. Thus the small sample we obtained there yielded an enormous amount of scientific data that has made the Armstrong Bay site worthy of preservation and eligible for placement in the National Register of Historic Places.

Archaeological work at Lake Vermilion State Park continues. I have no doubt we will uncover many more archaeological sites and keep building the story of human habitation at Lake Vermilion. Watch for interpretive displays at the park to bring you updates on our discoveries as we dig into the past.