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ISSUE 121 VOL 10 PUBLISHED 12/7/2007

Northfield: A Rocky History

By David Benson-Staebler
Staff Writer


Friday, December 7, 2007

Geology is the study of "geos," which comes from the Greek word for "land crust." The Greeks realized that land was indeed a crust, capable of moving periodically. Later, the science of geology became one of the "logos," the "studies" produced in the Enlightenment; the one that seeks to understand the earth itself. The geology of Northfield has been tumultuously shaped by glaciations, thaws and the whims of global weather.

The land on which St. Olaf is built is fresh and new, in geologic terms. It was built from a moraine, a pile of glacial deposits left behind when a glacier recedes. It was produced 11,000 to 14,000 years ago by the chafing of a mile high glacier against the large deposit. To the east of the Hill, a second moraine runs parallel to the Cannon River. The last glacier to traverse Northfield started melting not long after arriving at the Hill, but it was likely not the first to cover the land in ice. The flat top of Manitou Heights may have been the result of a previous scathing, possibly tens of thousands of years earlier.

The original crust of Minnesota was likely intact about 3.6 billion years ago. It is possible that the landscape was exposed 2.4 billion years ago. About 1.1 to 1.2 billion years ago, renewed geologic activity literally ripped across this landscape. Essentially, North America began to tear apart along a rift that extended from Lake Superior through this area and south to Kansas. The rift is responsible for the extreme depth of the Great Lakes. This crust underlies the land upon which St. Olaf sits.

Robert Jacobel, department chair and professor of physics, studies the glaciers of Antarctica. His research has broad applications that range from illuminating the geological patterns we see in our own homes to global issues, such as climate change. Since the United States has de facto authority over parts of Antarctica, the U.S. Geologic Survey has named a massive glacier after Jacobel for his research. Jacobel identified the large boulder in front of the science building as a relic of glaciation carried down from Canada. "It was pushed to the top of Manitou Heights by a glacier," Jacobel said. "Let no one ever think it was carried up the Hill by a human machine for ornamentation."

The torrent of runoff that resulted from glacial melt created the Cannon River and its tight passage through Northfield. As the glacier began to recede, its tip broke off, feeding the erosion of Heath Creek.

The Cannon River has also played a huge role in the geologic formation of Rice County and the area. The river itself drains a watershed of 1440 square miles, and from Faribault to its Mississippi River terminus near Red Wing, the river's elevation drops an average of 4.8 feet per mile.

With all that erosion action, it's a given that the river will play a large role in the topography of Rice County. Ninety percent of the land in the Cannon River watershed is dedicated to agriculture, which suggests that the soil of the area is well-suited to farming.

The river also has a profound local effect. The elevation is 912 feet above sea level, while the elevation of Manitou Heights falls between 1020 and 1051 feet, according to a digital elevation survey featured on the Rice County website. The community of Northfield falls into the shallow river valley the Cannon River has created.

The formations of sandstone and limestone on the Hill are the oldest prominent geologic feature on the surface of the Northfield area. Both types of rock are the result of ocean sedimentation when the Great Plains were submerged under a shallow continental ocean about 550 million years ago. Limestone was formed from biologic decay and sandstone from erosion. In the center of North America, somewhat parallel to the Rockies and Appalachians, there is a very small rift like the Great Rift of Eastern Africa, though geologic activity here today is quite limited. After the uplift of the Great Plains from the ocean, inland seas drained into the rifted areas, which were gradually filled with sediment deposited by glaciers when the climate cooled. This action continued to impact the land with each succeeding ice cycle over millions of years, giving rise to the stretches of flat land that characterizes America's heartland. While this activity has smoothed the land, evidence of Minnesota's marine past can still be found in fossil-hunting sites along Highway 8.

Fossils found in the Northfield area often include marine invertebrates. Corals, snails and clams are three familiar animals found, but more exotic species may also be present. Crinoids, also known as sea lilies, are beautiful invertebrates that resemble ornate flowers, as can the tilobite, as small and commonly sought-after relative of the lobster. Road cut-aways make good places to find fossils, especially after heavy rain knocks loose superficial debris.

The geology of Northfield has impacted the ecology of the area and resulting the ways in which the land can be altered to fit the lifestyles of its contemporary human inhabitants. Biologically diverse prairies which fed tens of thousands of bison and millions of prairie dogs once stretched across the Great Plains, but are now scarce in Minnesota. Though the efforts of biologists, ecologists, students, government grants and the administration at St. Olaf and Carleton have produced two plots of the prairie brought back to life in Northfield, giving the community a peek at the land's natural state.

Norwegians moved to America precisely for the ownership of productive land in Minnesota, a scare resource to the people living on the fjords. Due to the glacial flattening of Minnesota, the state contains an abundance of flat fields ideal for farming. Many others immigrated to provide services in the cities that were planned to provide services to the farmers. Since then many Norwegian-Americans have remained in the region but moved to the Minneapolis-St/ Paul area to work in the booming metropolitan economy.

The Northfield community has always been the bedrock of the St. Olaf community. Northfield Hospital was built on land the college has leased to it for the next hundred years. Around the hospital the College owns a few hundred acres that function as its buffer and passage way into the world of rural Minnesota farmland. The College's connection to agriculture is literal; many of St. Olaf's founders also owned farms and many alumni who own farms have contributed from the estate sale of lands to the college.

For many students who come from the Midwest ,the waves of grain and symmetry of corn remind them of the structure of the environment at home, and for radio listeners, this land recalls Lake Wobegon. Some foreign students describe living at St. Olaf as not really living in America, as there is a bubble enclosing the tranquility of the ultimate American pastoral. Some find this boring and anti-cosmopolitan; others find it spiritual or inclining to reflection. In any event, the response students and faculty have to the Northfield area is intimately connected to millions of years of geologic history, a history that has shaped not just the crust of the earth, but life at all levels on Manitou Heights.





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