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A Popular History of Minnesota
By NORMAN K. RISJORD
MINNESOTA HISTORICAL SOCIETY PRESSCopyright © 2005 Minnesota Historical Society
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Of Ice and Early Man
When the first settlers cleared land for farms in Minnesota in the early part of the nineteenth century, they noticed that the soil abounded with smooth, round stones of the sort usually found in streams and lakeshores. They brought an explanation for this with them from Europe: the earth had once been scoured by a great flood, described in the Book of Genesis. The Deluge had left a blanket of stony debris after its currents subsided. Farmers who dug wells found, beneath this diluvium, a layer of soil containing much organic matter and fossils of trees. Because this soil must have been in place before the great flood, it was called "the remains of Noah's barnyard."
In 1850 Harvard University offered a professorship to a Swiss geologist, Louis Agassiz. A decade earlier Agassiz had published a thesis arguing that a giant sheet of ice had once covered the continent of Europe. This glacier, he theorized, had deposited the smooth stones that dotted the farmland of Europe and scraped the curious striations on the rocky masses of the Swiss Alps. In the stony soils of New England Agassiz found further evidence for his glacial theory. Although he never reached Minnesota, the Harvard professor did lead an expedition along the shores of Lake Superior, where he found impressive signs of glaciation.
By the 1870s Agassiz's theory of glaciation had won general acceptance, and geologists in Minnesota began digging into the ancient history of the land. Examining soils, landforms, and sediments of nonglacial origin, they found evidence of four major expansions of glacial ice, interspersed with periods of warmer climates. The earliest, occurring about one million years ago, reached into what is now central Nebraska and was named the Nebraskan Ice Stage. The most recent, beginning about seventy thousand years ago, was named the Wisconsin Stage because of the profound impact it had on the state's topography. But the most recent glacial period might just as well have been called the Minnesota Stage, for it had an equally profound impact on the state. It not only wiped out most of the landforms created by the earlier glaciers, but it left behind the familiar topography of lakes, hilly moraines, and the water-hewn valleys of the St. Croix and Minnesota rivers.
Scientists are still not sure what caused the periods of glaciation. Possibilities include changes related to continental tectonic drift (which may have affected oceanic thermal currents or, by exposing newly formed rocks, permitted weathering to change the atmospheric levels of carbon dioxide) and changes in the earth's elliptical orbit around the sun. Because two-thirds of the land mass of North America lies north of the 45th parallel, the continent was especially vulnerable to the ice sheets. (The 45th parallel passes through the Twin Cities.) Glaciers began in mountainous areas or near polar regions when snow did not melt in summer, and they fed upon themselves. As sheets of ice spread out in a period of global cooling, they reflected the sun's rays back into space, contributing to the cooling.
The Wisconsin Stage glaciers originated in northeastern Canada, and as the snow piled up year after year and century after century it reached a depth of almost two miles. So heavy was the ice that it put a dent in the earth's crust, the remains of which are known today as Hudson Bay. When a glacier grows to about two hundred feet high, the immense weight of snow and ice causes the ice at the bottom to become flexible and, depending on the incline of the land, the mass begins to flow. New snows replenish the ice mass so the movement can continue, reaching a pace of as much as two hundred feet a year. The moving ice scoured the earth down to bedrock in many places (basalt and granite in Canada and northern Minnesota) and pushed the till of sand and rocks like a gigantic plow. The ice did not advance evenly, for it was detoured by high spots and ancient river beds. The fingers, or lobes, at the forefront of the glacier advanced, stalled, and advanced again with short-term changes in climate.
Over tens of thousands of years, several lobes of the ice sheet advanced and retreated across Minnesota, rearranging the landscape. The peak of the most recent glacial trek occurred about fourteen thousand years ago, when the Des Moines lobe swept down from the northwest, covered most of the state, and reached into central Iowa, the farthest penetration of the Wisconsin period. None of these icy projections reached southwestern Wisconsin or the southeastern corner of Minnesota, an area known today as the Driftless Region.
The Great Meltdown
South of the great ice mass in what is now Minnesota lay patches of tundra, grassland, and spruce parkland that stretched to the Ohio and Missouri rivers. Beyond the rivers, a spruce forest reached almost to the Gulf of Mexico. The deciduous forest of oak, maple, beech, and walnut that covers much of the United States today was largely confined to Florida and Texas. In the southwestern part of the continent, moist air from the warm Pacific created a land of freshwater lakes and pine forests. A land bridge across the Bering Strait between Alaska and Siberia separated the warm Pacific Ocean from the frigid waters of the Arctic. Warm Pacific currents preserved large parts of Alaska from glaciation.
About fourteen thousand years ago the earth began to warm again. The glacial lobes halted their advance and then began to melt. Short-term changes in climate of one or two hundred years turned the retreat into a stutter-step, and at each brief halt the lobes left a ridge of earth and stone, or a moraine. The Des Moines lobe, for example, deposited what is known today as the Big Stone Moraine, which essentially forms the divide between the Minnesota and Red River valleys. To the east, the retreating Superior lobe left a moraine around the western and southern sides of Mille Lacs, while furnishing the initial waters of the lake. Melting glaciers exposed till piled up into oblong hills or drumlins that paralleled their flow and conical hills or kames near terminal moraines. Rivers of water flowing in tunnels under the ice deposited sand and gravel in winding ridge-like hills called eskers.
The melting ice, together with the depressed earth's crust, created a gigantic freshwater lake that extended from Browns Valley into southern Canada. In 1879 geologists honored the originator of the theory of glaciation by naming it Lake Agassiz. Glaciers to the north and east prevented the lake from draining in those directions, and the waters built up until they eventually topped the Big Stone Moraine at the head of the Red River Valley. Spilling through the moraine, the glacial River Warren, larger than any in North America today, carved out the huge valley in which the Minnesota River now flows. As the river reached an older valley where St. Paul now stands, it formed an immense waterfall. The falls, formed by the erosion of soft sandstone under a thin layer of brittle limestone, crept northward over thousands of years, at the rate of two or three feet a year, some eight miles up the Mississippi. Now known as St. Anthony Falls, they were protected by a concrete apron in the 1860s.
About ten thousand years ago the melting of ice north of Lake Superior opened a new outlet for Lake Agassiz to the east, the lake level dropped, and the divide between the Minnesota and Red rivers was created.
As the climate warmed, the spruce forest spread across Minnesota and then was replaced by pine. Prairie grasses spread northward out of Kansas and Nebraska, reaching southwestern Minnesota about ten thousand years ago. North and east of that boundary the empire of pine and spruce held on. Animals moved in with the advance of vegetation. Some, like the Columbian mammoth, the mastodons (relatives of the elephant), and the giant sloth, had been around for millions of years, dating their ancestry to the New World's early contact with Africa. Others, like the famous wooly mammoth, originated in Siberia and came across on the Alaskan land bridge. Also prowling the forests of Minnesota were a variety of meat-eating animals—wolves, bears, and cats, large and small. Some had originated in North America; others had crossed on the land bridge. The short-faced bear, which evolved in North America, dwarfed the modern grizzly and was the largest meat-eating mammal ever to have trod the earth. Equally fearsome was an American lion twice the size and weight of the modern African lion. The saber-toothed cat, which used its extended canines to disembowel its prey, owed its ancestry to African or Asian origins and was an American relic, its ancestors in the Old World having become extinct several thousand years earlier.
All of these huge animals became extinct in North and South America within a few thousand years before and after the arrival of human hunters. Perhaps skilled early hunters contributed to the die-off. Many of the lumbering giant mammals, who had little fear of puny humans, would have made good targets. On the other hand, the same massive changes in climate that made much of North America habitable by humans may have made the area less hospitable for these large mammals.
The earliest reliable evidence of humans in the Americas was first uncovered at a site near the village of Clovis, New Mexico. The principal evidence for their existence is a tool, a spear point finely chiseled out of flint or chert, with a sharp point and hollowed-out ("fluted") sides so that it could be firmly affixed to a wooden shaft. Campsites and projectile points of the Clovis people, all dating from 10,000 to 9000 BC, have been found at various places in North America, especially in the Great Plains. It is likely that they began coming across the Alaskan land bridge at the beginning of the warming period. Although the land bridge had been in existence for thousands of years, the frozen tundra of Siberia discouraged Asian peoples from moving much north of the 54th parallel until the climate began to warm. About fourteen thousand years ago, at a site on the shore of the East Siberian Sea, people scavenged dead and dying mammoths swept to the sea by the Berelekh River. These people may have been the first pioneers to venture east and south along the shore of North America. In Alaska they would have found more of the same—mammoths, bison, elk, and deer—a fauna that they had been feeding upon as they crossed Asia. Interestingly, however, no Clovis spear points have been found in Siberia. The Clovis spear point seems to have been an early New World invention by the people now known as Paleoindians.
The oldest burial site in Minnesota, dated to about nine thousand years ago, is in the Big Stone Moraine near the town of Browns Valley on the headwaters of the Minnesota River. A man's skeleton, its bones stained with red ochre, was found in a gravel pit with a finely flaked stone knife and a smaller projectile point of a type known as Plano, which does not have the fluting characteristic of the Clovis implements. Plano points have been found throughout Minnesota. It thus appears that hunters of the late Paleoindian Tradition pursued both the buffalo of the prairie grasslands and the deer and elk of the northern forests.
Over the next thousand or so years people of what is called the Archaic Period developed woodworking tools such as chipped stone axes and adzes, new forms of scrapers and knives, and punches that must have quickened the process of turning animal skins into clothing. At a campsite in Itasca State Park dated to about 6000 BC, archaeologists found stone tools and the bones of bison that had been scarred in butchering. This species of bison, now extinct, was much larger than the modern bison or buffalo. It is likely that the hunters drove the animal into a swamp and then speared it as it struggled in the muck. Archaeologists also found at this site the skeleton of a domestic dog, the first evidence in Minnesota. A female skeleton of the Archaic Period was uncovered at Pelican Rapids, about a hundred miles to the north of Browns Valley. An antler tool and the shell of a salt-water clam, probably from the Gulf of Mexico, were found with the remains. This skeleton—known as Minnesota Man before being renamed Minnesota Woman in 1968—has been dated to 6700 BC.
From about 5000 BC to 1000 BC (when Egyptian and Mesopotamian civilizations were growing and thriving), people around the western Great Lakes began using copper tools. They used stone hammers to pound raw copper nuggets they found on Michigan's Keweenaw Peninsula and in glacial deposits throughout the region. Their copper spear points, knives, fishhooks, and awls were the first metal tools in the New World. One of their habitation sites in Minnesota, Petaga Point, is located on what is now the picnic ground in Mille Lacs Kathio State Park. This settlement may date to about 1500 BC.
Some time between 1000 and 500 BC people of the Woodland Tradition began to make pottery and to bury their dead in earthen mounds. One of their most common tools was a grooved hammer-stone, a spherical stone encircled by a shallow groove so it could be tied to a handle with a rawhide thong. This grooved maul could be used to pound dried beef and berries together. (The pounded mixture of dried beef and berries, or pemmican, was a staple of the regional diet into modern times.) People of this tradition continued to use copper tools, but they also made great use of bones and antlers to fashion hide scrapers, awls and punches, carved dice for games, whistles made of bird bone, and barbed points for spearing aquatic mammals and fish.
At some point late in the Woodland Tradition (probably in the first centuries of the modern era) the bow and arrow made its appearance. Both hunting device and weapon, the bow and arrow was first used by the peoples of Asia. Whether it made the crossing from Siberia or was reinvented in America is a matter of conjecture. The bow and arrow enabled hunters to kill game at greater distances. The prevalence of arrow points throughout North America after this time suggest that the new technology spread rapidly among the Woodland peoples.
The pottery made by these people was at first quite utilitarian. One of the earliest excavated Woodland sites is on Grey Cloud Island in the Mississippi River bottoms near Hastings. The clay vessels found here are thick walled and flowerpot shaped. They had little decoration and no handles. They were used for cooking simply by being placed in a bed of hot coals. Later sites contain pottery of more complex construction. The Laurel people, who lived in the boundary waters area and in Ontario, made thin-walled pottery fired hard and decorated with impressions from a toothed stamp. A form of pottery, the tobacco pipe, also came into use about this time. Initially made of clay, pipes were later carved from a red stone (catlinite) found at the Pipestone quarry of southwestern Minnesota.
The mounds of the Woodland peoples were generally small, low, and round. The largest in the state, built by the Laurel people on the Rainy River, is Grand Mound, one hundred feet in diameter and forty feet high. The mounds contain human bones, shards of pottery, and occasional tools.
The Mississippian Tradition
About one thousand years ago, a new tradition reached the upper Mississippi area. Influenced by civilizations in Mexico that had built enormous pyramids in which to bury kings, people of the Mississippian culture built some large settlements with central plazas and huge earthen mounds on which they erected temples and conducted religious ceremonies. Leading families also lived on and buried their dead in mounds; others families lived around them. They raised crops of corn, beans, squash, and sunflowers in fields cleared in bottomlands.
Sometime around AD 1000, while the Norsemen were establishing the first European settlement on the coast of Newfoundland, the Mississippians erected a major population center at Cahokia, Illinois, near the mouth of the Missouri River. Its largest ceremonial mound stands 100 feet high (after centuries of settling and erosion) and measures 700 feet by 1,000 feet. The entire complex occupied sixteen acres. From this center smaller settlements fanned out into the area that became Minnesota and Wisconsin. Several large village sites and dozens of smaller sites near the point where the Cannon River enters the Mississippi north of Red Wing show influences of Mississippian culture, including pyramided earthen mounds and pottery. The larger settlements may have contained 600 to 800 people, who tended garden plots on terraces above the rivers and dug deep underground storage pits for the wintering of vegetables. Like the Woodland peoples, the Mississippians hunted deer and speared fish in the rivers.
Excerpted from A Popular History of Minnesota by NORMAN K. RISJORD. Copyright © 2005 Minnesota Historical Society. Excerpted by permission of MINNESOTA HISTORICAL SOCIETY PRESS.
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