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In order to count this Earthcache as a find, you must complete the following tasks and email the answers to me.
1. Estimate the width of the river.
2. Describe the course of the river as far as you can see in both directions from ground zero.
3. Estimate the speed at which the river is flowing.
This Earthcache is located just south of Columbia, South Dakota where the James River flows through the area. From beginning to end, the James River is 747 miles long. Although officially classified as a navigable river, it has long been considered by many as the longest unnavigable river in North America. Enjoy!
The Sioux first called the river Tchan-Sansan, meaning “the river of the white woods.” In 1794, Jean Trudeau, a Frenchman, named it the Riviere aux Jacques. Years later, a territorial legislature titled it the Dakota River. Today, we call it the James, or Jim River, after the French name.
The James River begins among the tiny lakes, marshes, and potholes of central North Dakota. Its origin is between the small towns of Hurdsfield and Fessendon. At first glance, the River appears to be a small bay on a prairie lake’s eastern side. However, the bay-like body of water is long and thin and twists around the base of a grassy hill away from the marshy fringes of the lake, thereby separating and distinguishing itself from its source.
The River flows away from the lake and descends the rolling hills of the northern prairie. Early on, the James River is no more than a mere drainage way that collects the rains and melting snow that feed and eventually transform the rivulet into a more defined stream. Further south, its size grows to accommodate the accumulation of runoff, and the James River stream becomes a prairie river.
As with nearly all of the eastern Dakota prairie, glaciers have been the key factor in determining the look of the land and its wetlands and watercourses. The natural evolution of the James River has been orderly and slow. In northern South Dakota and southern North Dakota, however, this transformation has been much more dramatic and has left the river with a particularly flat and circuitous course.
Somewhere between two and three million years ago, during the Pleistocene Epoch (the Ice Age), at least four major ice sheets descended into South Dakota from the north. Many thousands of years separated each advance, with glacial retreat and melting ice occurring during the long intervals. Less is known about the first three periods of glaciation than the final one, the Wisconsin Age. About 18,000 years ago, the Wisconsin ice sheet began receding as temperatures rose. The landscapes that had been influence by the massive bulk of ice lay exposed. Deglaciation was a gradual process involving the melting of ice six million square miles in area and two miles thick at the center. The final phases of glacial melt in eastern South Dakota took place as recently as nine or ten thousand years ago. As the glaciers melted, large amounts of runoff resulted. This runoff transformed into rivers and streams. The majority of this runoff, however, pooled into a large, ancient lake called Lake Dakota.
Lake Dakota stretched over 100 miles in length and occupied what is now a broad, shallow valley that begins in North Dakota, just above the South Dakota border, and extends to southern South Dakota. A blockage in the southern reaches of the lake caused slow drainage of the pooled meltwater. This bottleneck blockage was the narrowing of the James River Valley. Geologists believe the large lake was short-lived as far as lakes go, existing for only two or three thousand years. When drainage was finally complete, a trench 100 feet deep and nearly a mile wide lay on what had been the floor of the lake. Within the trench was a narrow crease that became today’s James River channel. This trench serves as the river valley.
As the James River nears its confluence with the Missouri River near Yankton, its channel broadens and deepens. Because so much of the James River lies on what once was the flat floor of Lake Dakota, there is very little elevation drop to help speed the river’s flow. While many rivers have a drop of several feet to the mile, the James River has a grade of only a few inches to the mile. Consequently, the James often appears motionless. It has been described as a river that “purrs, seldom roars.” In some places, the atmosphere along the river--especially in areas of lush vegetation--is bayou-like. The winding channels and horseshoe-shaped bends reflect the slight gradient and slow-moving flows of the River. Normally, these bends would be cut off from the river and transformed into an oxbow lake by a process called erosion. This causes the river to take a more direct route. However, the sluggish flows of the James River cannot carve and maintain a straight, direct channel. New channels are created only after many years, but the meandering pattern of the river will not change.
Resources:
Carrels, Peter. "The James: River of the Prairie." South Dakota Magazine, January 1986: 12-15. Print.
NOT A LOGGING REQUIREMENT: Feel free to post pictures of your group at the area or the area itself - I love looking at the pictures.
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