Helping Boats Climb and Descend
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THE UPPER MISSISSIPPI RIVER This coordinates takes you within the zone of an observation deck where you can enjoy a panoramic view of the mighty Mississippi River.
Directions: From Alton, IL: From the Clark bridge, follow IL 143 South two miles to Lock & Dam Way. Turn right. From I55/64/70 (downtown St. Louis): Go East across the Poplar Street bridge. Take the 3 North exit. Follow it all the way to IL 143 near Wood River. Turn left onto IL 143, and go 2 miles to Lock & Dam Way. Turn left. Phone: 1-877-462-6979 ANCIENT SEAS During the Paleozoic Era, 500 to 400 million years ago the continents experienced tremendous mountain building and many times shallow seas covered North America. The first ancient organisms such as crinoids, coral, brachiopods and trilobites appeared. The fossilized remains of the inhabitants make up the many layers of limestone deposited on the flat-bottomed sea and are now buried below the many bluffs that border the river floodplains. THE ICE AGE Between 10,000 and 1.6 million years ago this area of the earth experienced four periods of ice and thaw, glaciers carved North America. Huge lakes and rivers came and went. With each glacial retreat, icy melt-water cut the upper Mississippi River deeper into the rock. Ice sheets from the East and West also pushed the Mississippi sideways, forcing it into the Illinois River for a time. This is why the Illinois River Valley is so large. Ten thousand years ago the Ice Age ends. The Mississippi River is fully formed. PLEISTOCENE DEPOSITS AND LANDFORMS The Glossary of Geology describes a floodplain as the surface or strip of relatively smooth land adjacent to a stream channel that has been produced by the stream's erosion and deposition actions; the area covered with water when the stream overflows its banks at times of high water. It is built by alluvium carried by the stream during floods and deposited in the sluggish water beyond the influence of the swiftest current. The upper Mississippi River floodplain just north of the posted coordinates is largely inundated by backwater from the Melvin Price Locks and Dam at Alton, Illinois. Studies of the sedimentology and bathymetry (measuring water depth and charting bottom topography) of the Illinois and Mississippi Rivers were conducted in Pool 26 above the locks and dam at Alton by the Illinois State Water Survey, the Illinois State Geological Survey, and the Illinois State Natural History Survey in the early 1980s. The Surveys were examining the effects of boat traffic on inhabitants of the riverine ecosystem (Schnepper et al. 1981, Goodwin and Masters 1983). They found that, with few exceptions, bottom materials in the deeper parts of the channel, where it has been dredged for navigation, are mainly sand. In shallower parts of the channel bottom, silt is the major constituent of the sediments. Navigation traffic may contribute greatly to the relative lack of clay and silt in the deeper parts of the channels. Bottom-dwelling organisms living such as clams, mussels, and worms (food source for fish, ducks, and early man) have difficulty living in a sandy habitat. Creating wetlands along the valley bottom floodplains, as some government agencies are now doing, should improve bottom habitats outside the navigation channels. This in turn will provide a better environment for fish and waterfowl. ON GOING CHANGE ---- MODERN EPOCH Each river is shaped by many things: its speed, the sediment it carries, the slope it runs down, the rock over which it passes and even the plants (riparian) nearby. Change anything and the river behaves differently, taking a new path. Ten thousand years ago through tomorrow the great cycle continues. Rain and snow-melt fill the Mississippi River, which in turn feeds the Gulf of Mexico. Wind and water erode rocks and wash away soil. The river carries and deposits this sediment down stream ….constant change. Many thanks to Jessica Harder, Park Ranger, U. S. Army Corps of Engineers – St. Louis District for providing the guidelines necessary to obtain permission to establish an EarthCache at this location and to the museum staff for providing some of the educational information contained in this publication. The National Great Rivers Museum at the Melvin Price Locks and Dam is located within a short walking distance from the posted coordinates, and it contains a wealth of educational material. It is open 7 days a week from 9 a.m. to 5 p.m. All programs and tours are free. The museum itself is self-guided. The staff does conduct tours of the locks and dam daily, for public walk-ins only, at 10 a.m., 1 p.m., and 3 p.m. Both the museum and locks tour are handicap accessible. Group tours are also available and may be scheduled by calling 1-800-258-6645. IN ORDER TO LOG THIS FIND YOU MUST: Take a picture of yourself with your GPS device at the designated coordinates. Log the find and post the picture on the Earthcache page. Email the answers to the following questions to me. Do not post the answers to the questions on the Earthcache page. 1) The Mississippi River bed is shallow at this area causing the river to meander from side to side. What is the term used to describe the results of this erosion and deposition action? 2) What is the elevation at the posted coordinates from the observation deck?
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