Thursday, September 6, 2007

On the Section Line

A survey marker in the Lower Arboretum.

Flying over Iowa on the last leg of our journey home from England, I knew I was back in the American Midwest. From the window of the plane, the landscape below looked like graph paper—a regular grid of green fields bounded by light gray roads. This landscape is the legacy of the great land survey that began near the banks of the Ohio River in 1785 and moved steadily westward as new land opened up for settlement. The survey mapped the land into a regular of six-mile-square townships, each divided into 36 one-mile-square sections. Rice County, for example, comprises fourteen separate six-mile-square townships (with a slight deviation, since Bridgewater and Northfield townships together include an extra twelve sections annexed from Dakota County, and are therefore not perfectly square). Each section is numbered. Our house on Fifth Street, for example, is in section 6, Township 111N (numbered relative to a baseline running east-west), Range 19W (numbered relative to a north-south principal meridian).

A detail from a map of the arboretum, showing the section line and raised path to the mill ruins (click to enlarge).

One of my favorite places to go and contemplate the landscape history of the Northfield area is in Carleton’s Cowling Arboretum. About a mile into the Arb along the main path closest to the Cannon River, a narrow path, raised above the level of the surrounding floodplain, leads to the river directly across from the ruins of the Waterford Mill. The ridge of earth along which the path runs is probably the old dike, or retaining wall, from the mill pond. What I find remarkable is that the dike exactly follows the section line separating sections 29 and 30 of Township 112N Range 19W, as you can see in the detail from the arb map at left. I find this line convenient because, if you follow it south from the river, it traverses three of the major ecosystems that were present in Northfield at the time of white settlement in the 1850s: floodplain forest, oak savanna, and prairie.

Looking north along the section line from the south bank of the river at the Waterford Mill ruins.

Beginning here at the river, the line crosses through floodplain forest, dominated by large, fast-growing trees like silver maple, green ash, and cottonwood that take root quickly in the rich silt of the floodplain. At the time of settlement, a major ford crossed the river here, and traces can still be seen of a much later bridge across the river on the site. The Waterford Mill, or Grange Mill, was built in 1873 as competition for Northfield’s Ames Mill; it was abandoned in 1909. The mill ruins are in the center of the photograph above (I was being devoured by mosquitoes when I took this picture).

Looking north along the section line at the oak savanna.

Moving south along the section line, the land slopes upward away from the floodplain and becomes oak savanna. Until a few years ago, a pine plantation stood here, between floodplain and savanna, and a small section of the plantation remains standing a little further northeast along the main path. The pines were planted in the 1920s and 1930s when Professor Harvey Stork used the arboretum to teach forestry classes. (Carleton College's connection to the Minnesota white pine industry is witnessed by Laird Hall, named for timber baron and college benefactor William Laird.)

Looking south along the section line at the prairie restorations.

Near the edge of the oak savanna, alongside the path, a Dakota County survey marker marks the section line (above). To the south of this marker, the oak savanna gives way to prairie. The prairie here is a recent restoration, using native prairie seeds obtained from McKnight Prairie. Follow the section line further and it joins Hall Avenue, east of Northfield.

The best general audience book on the creation of the American grid system is Andro Linklater's Measuring America: How the United States Was Shaped by the Greatest Land Sale in History (New York: Plume Books, 2003).


John Mutford said...

Where my wife is from in Ontario is similarly divided into grids. The first time I went there, I didn't appreciate it. I'm from outport Newfoundland where most communities are spread out along the coast. I've since seen the charm in both!

fabrile heart said...

What a fantastic post. The little air travel I have done across America always sets me thinking about the diversity and sheer vastness of States. I shall have to look out for the book you mention.

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