Geology and Geomorphology
The Cuivre River Basin lies in the Dissected Till Plains of the Central Lowland Physiographic Province (Fenneman 1938). This area is a part of the Glaciated Plains Natural Division (Thom and Wilson 1980)(Figure Ge01). It is characterized by soils and topography resulting from the influence of the Kansan stage of Pleistocene glaciation. The western and northern portion of the basin lies in the Eastern Section of the Dissected Till Plains and the southeastern and eastern edge of the basin lies in the Lincoln Hills Section.
The Eastern Section has claypan soil and the land is generally flat except for steep hills near streams. Shale underlies most of this area. Aquifers and recharge to streams during dry periods are poor. Stream substrates are dominated by sand and silt. Stream water is frequently turbid from large quantities of fine sediments in runoff water (Pflieger 1971).
Historically, prairies dominated the upland landscape. Deciduous trees grew in rugged areas and bottomland trees grew along the streams. Wet prairies and springs were uncommon.
Terrain in the Lincoln Hills Section is hillier and steeper than in the Eastern Section. Limestone replaces shale as the predominant bedrock and some karst topography is present. The streams tend to be clear and have substrates of gravel and rubble.
Presettlement vegetation was mainly deciduous forest with prairie constituting less than 5 percent of the section. There were also glade, cliff and march communities. The flora and fauna of this section are similar to that found in the Ozarks (Thom and Wilson 1980).
Pennsylvanian shales and sandstone are the principal bedrocks of the region (Figure Ge02). Mississippian and older rock, primarily limestone, line the surface along the Mississippi River. Lincoln and Pike counties show some karst topography.
The stratum in the region generally slants to the west. Many limestone areas have east-facing escarpments hidden by glacial drift. Some escarpments are at least 50 feet thick.
Soils developed from glacial and loess deposits. Loess deposits vary from a few feet to 90 feet in depth. The land has a submature-to-mature erosion cycle. Relief is from 100 to 300 feet.
Streams meander through broad valleys dotted by many oxbows and sloughs. The channels typically are bordered by high alluvial banks. The pools are generally long and riffle sections are sometimes lacking or are poorly defined. Silt, sand and gravel are common substrates. Water flows tend to be intermittent or have a low base.
The following list identifies the geological characteristics for the basin by county (Missouri Department of Natural Resources 1986):
•Audrain - characterized by Pennsylvanian (Desmoinesian Series) rock types which consist of alternating thin limestone, shale and sandstone. Coal deposits and clay also are present.
•Lincoln - primarily Mississippian formation of limestone, shale and sandstone. Near the Mississippi River flood plain quaternary alluvium predominates.
•Montgomery - contains Pennsylvanian and Mississippian formations of limestone, shale and sandstone, coal and clay.
•Pike - a combination of Pennsylvanian and Mississippian formations.
•St. Charles - generally Mississippian formation of limestone, shale and sandstone. Near the Mississippi River flood plain quaternary alluvium predominates.
•Warren - is Mississippian formation composed primarily of limestone, shale and sandstone.
The majority of the West Fork Cuivre River subbasin lies in the Central Claypan region. Its soil is a poorly draining type known as a Putnam-Mexico (Soil Conservation Service 1979). The silt-loam surface overlies a silty clay subsoil. The landscape tends to be nearly level to gently sloping; slopes range from 0 to 5 percent. Stream valleys tend to be shallow and narrow. Alluvium is present in the river bottoms. This region was originally covered by prairie grasses but is now heavily cultivated. This soil is well suited for growing corn, soybeans, grain sorghum and hay crops.
The remaining areas of the West Fork subbasin and most of the North Fork Cuivre River and Cuivre River subbasin lie in the Central Mississippi Valley Wooded Slopes region. The soil types are Hatton-Keswick-Lindley-Goss, Menfro-Winfield-Lindley, and Hatton-Keswich-Goss-Gasconade (SCS 1979). In general, these soils formed under prairie and forest vegetation.
They tend to be well-drained loamy and clayey upland soils with some areas of chert. Ridgetops are gently sloping but valley sides can be very steep, up to 50 percent. Small fields of grain sorghum, corn or hay are commonly found on ridgetops. Steeper valley sides are often pastured or left in forest.
Lastly, a small area near the mouth of the Cuivre River is in the Missouri and Mississippi Alluvium region (SCS 1979). This alluvial (waster-deposited) soil is quite deep and is a mixture of silt, loam and clay. The landscape tends to be moderately flat with large bottomland crop fields; slopes do not exceed 3 percent.
Stream order was determined using the Strahler method (Strahler 1959) from United States Geological Survey (USGS) 7.5-minute topographic maps. Within the basin are 112 third-order-and-larger streams. Of these, 84 are third order, 21 are fourth, four are fifth, two (the North Fork Cuivre River and the West Fork Cuivre River) are sixth and one (the Cuivre River) is seventh (Table Ge01, Table Ge02, Table Ge03). Each third order-or-larger stream was assigned a code number based on a 1981 method devised by Pflieger, Haverland and Schene Jr. 1981). The North Fork and West Fork Cuivre rivers were given two code numbers because of their length. Segment 1 includes the sixth order reach and segment 2 includes the fifth-order-and-smaller segments.
Watershed Area/Stream Length
Watershed area and stream length for third-order-and-large streams were determined from USGS 7.5-minute topographic maps. Appendix A summaries the dates and names of these maps. The watershed area was digitized using PADPAC software (Taylor 1988) on a Houston Instrument True Grid Digitizing tablet, Model T.G.-1017; stream mileage was measured with calipers.
The total Cuivre River watershed is 1,235 square miles. The Cuivre River (below confluence of the North Fork Cuivre River and the West Fork Cuivre River) is 32.6 miles long and drains only 305 square miles. The North Fork and West Fork rivers are 37.9 and 76.8 miles long and drain 346 and 584 square miles, respectively. Measuring from the mouth of a stream to its headwaters, there are 420.9 miles of third order streams, 155.1 miles of fourth order streams, 93.9 miles of fifth order streams, 114.7 miles of sixth order streams and 32.6 miles of a seventh order stream (Table Ge01, Table Ge02, Table Ge03).
Gradient information for fourth-order-and-larger streams was obtained from USGS 7.5 minute topographic maps. Gradient plots of these streams are provided in Appendix A (Contact authors for information from Appendix A). The Cuivre River is a low-gradient stream, averaging 1.2 feet per mile. The gradient of the West Fork Cuivre River changes from 4.1 to 16.6 feet per mile along its length and the North Fork Cuivre River increases from 3.2 to 40.0 feet per mile at it's headwaters (Table Ge04; Figure Ge03). In general, the gradients of major tributaries are lowest in the West Fork Cuivre subbasin. This drainage encompasses the largest portion of the basin's Central Claypan Area. This soil formation is characterized by fairly low relief with slopes from 0 to 5 percent.