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Cache River, Southern Illinois
The Challenge
The Cache River Basin in southern Illinois is a unique ecosystem holding important wetlands, including one of only sixteen in the United States listed by the United Nations’ UNESCO division as wetlands of “international importance.” Before logging and conversion to agriculture, over 240,000 acres (97,124 ha) of the Cache River’s watershed were covered with cypress-tupelo (Taxodium distichum, Nyssa aquatica L.) swamps. Today, the area holds two of the largest cypress trees in the United States and some of the oldest living cypress trees known. The Cache River Watershed in southern Illinois has a complex natural history influenced by glaciation, perhaps tectonic events in the past 1,000 years, and certainly by radical alteration after European settlement.
In 2005, LRRD was hired by the Cache River Joint Venture Partnership to investigate the evidence for water levels in the middle Cache River Valley prior to extensive drainage network alteration beginning in the late 1800s. Our research included analysis of historical records and geomorphology of the Cache Valley, and may have uncovered evidence that some wetlands in the Valley have origins as “sunklands” formed by tectonic events in the past 1,200 years.
Download our full report here.
Clients/Cooperators
The Cache River Joint Venture Partnership, The Nature Conservancy, the Illinois Department of Natural Resources and the US Fish and Wildlife Service, with the Natural Resources Conservation Service, Illinois State Geological Survey, and siesmologist Martitia Tuttle of M. Tuttle and Associates.
Excerpt from the 1903 “Bell Survey,” which included a long profile survey of most of the Cache River. This survey, which included streambed and bank elevations, was analyzed to determine geomorphology of the river before it was altered. Here the red line is the surveyor’s proposed channelization route.
A plat map, date unknown, drawn from the 1807 Public Land Survey of the Cache River. These plats were invaluable in determining the extent of flooded land when the survey was done. From the Illinois State Archives.
Excerpt from the USGS Dongola 15′ quadrangle, published in 1919, showing early channelization of the lower Cache. During the first part of this century the Cache’s valley was extensively altered by logging and drainage projects.
Cache River Details
The sunken part of the Cache Valley, which I’m calling the Middle Cache Valley (MCV) is labeled “Buttonland Swamp.”
The work described here is a synthesis of existing literature and information on the hydrology of the Cache River aimed at these questions: Did the Middle Cache Valley (MCV) hold permanent water prior to European settlement, and, if so, at what average elevation? The Cache River Watershed has an exceedingly complex natural history greatly influenced by glaciation, perhaps tectonic events in the past 1,000 years, and certainly by radical alteration after European settlement. We have two powerful and objective sources of historical evidence: The 1807 Public Land Survey (PLS) records, and the 1903 Bell survey. The PLS clearly shows that the MCV was flooded to an elevation of at least 330 ft. NGVD at the time of the survey. The MCV is subject to floods of long duration, but the PLS surveyors described flooded areas in the MCV using terms such as “lake,” and “pond.” It seems unlikely that these experienced geographers, would have described temporarily flooded timber using such terms.
Part of the plan map from Bell’s 1903 survey of the Cache River. The “Big Four” railroad and village of Belknap are shown.
The Bell survey, done in 1903, gives us a long profile 93 miles (150 km) of the Cache River. This survey shows that an eight mile (13 km) section of the MCV is sunken, and clearly not in fluvial equilibrium with the rest of the Cache River. Over a period of thousands of years of Cache River flows and Ohio River overflows since the Pleistocene, this sunken section should have reached an equilibrium form with reaches upstream and downstream. This lack of equilibrium begs explanation and may have resulted from earthquakes. Recent work in the Cache Valley has dated at least one strong shock to about 900 years ago (Guccione 2002).
Regardless of the genesis of the sunken parts of the MCV, it is clear that they held permanent water before alteration by European settlers. The Upper Cache River holds several wetland areas, remnants of glacial lakes, that also were poorly drained swamplands. These areas held water at higher elevations and with much smaller drainage areas, strongly suggests that the MCV was well supplied with water and tended to hold it. Bell (1905) and others described the numerous dense logjams in the area, specifically noting that some of them barely let a trickle of water through. Considering this evidence in light of the depressed nature of the MCV as shown by Bell’s long profile survey, it seems likely that these dams acted to keep permanent water in the MCV.
- PDF of long profile taken from Bell’s 1903 survey of the Cache River showing the depressed Middle Cache with its unusual (out-of-equilibrium) long profile. The plot shows bed and bank heights as surveyed in 1903. Bank and bed points in the depressed (“sunk lands?”) middle section are mathematically separated from upstream and downstream data to show how this section of the valley is not in fluvial equilibrium with the rest of the Cache River Valley. A river with a significant sediment load will smooth bed and floodplain lines (at least over this large scale) very quickly, I would guess in this case over a few hundred years. Note the parallelism of bank and bed lines in the separated data.
- Cypress quad excerpt, showing circular crater-like features (arrows). Note also sunken areas in Section 7, and large ponds (NE quarter Section 14) in the Cache River that do not appear to be scour features. Eagle Pond is the smaller of the two.
- Excerpt from the Karnak 7.5′ quad showing craters. Note also the large fluvial features trending east-west. And a recent ground photo of an extant crater at this site (the “small crater at the base of the levee”). We investigated this crater on 9-4-2005 and it does exist. It is close enough to the levee, though, that it could be a sand boil formed during high water inside the levee.
- Map of faults in Southern Illinois, from a W.J. Nelson report on faulting in Southern Illinois.
- Photo of “craterlet” from Fuller’s 1912 New Madrid report.
- Very large fluvial bars, from the 7.5′ Karnak quad.
