**9. The geological history of the study area**

The Mississippi River embayment was initially created by an ancient down warping of the crust, presumably by tectonic forces. Confining our discussion to the Pleistocene-Holocene the ancestral Mississippi River occupied an Advance Lowland course until the late Wisconsin sub-stage [6, 11, 12]. These authors proposed that the diversion of the Mississippi River through the Bell City—Oran Gap, abandoning the Advance Lowlands and entering the Morehouse Lowlands, was initiated approximately 17,000 year BCE (before common era) and was complete by 11,500 year BCE. By 9800–9900 year BCE, the Mississippi River changed from a braided river to meandering river, passing through the Pemiscot Bayou [12]. After the diversion, the advance lowlands continued to receive sediment from the Ozark Plateau, principally from the Little Black River, the Current River, the Spring River, and the White River. Blum et al. [13] proposed that the Bell City—Oran Gap diversion into the Morehouse Lowlands occurred before 60,000 year BCE, thus placing the Bell City—Oran Gap diversion before the Wisconsin glaciation. Royall et al. [12] proposed that the Ohio River produced two braided stream terraces in the Morehouse Lowlands between Crowley's Ridge and Sikeston Ridge. Blum et al. [13] map Sikeston Ridge as a late Wisconsin valley train having a very thin loess capping of Peoria Loess. Blum et al. [13] further attribute the Blodgett terrace as a braided terrace deposit of the Ohio River, which was entrenched within the Cache River Valley (Illinois). Based on carbon dating, Blum et al. [13] place the Charleston Fan as a Mississippi River feature formed during the creation of Thebes Gap (10,590 year BCE).

The area also has the highest percentage of level and tillable land, of which 60–70% is irrigated with abundant groundwater resources. Animal agriculture is very small, consisting of a few

In southeastern Missouri, there are 4133 farms [9]. Cape Girardeau County has more than 1100 farms, thus approximately one-quarter of all farms of the eight-county region are in Cape Girardeau County. In the Mid-South region, Stoddard County has the largest number of farms, many of which are smaller farms on upland hills. The range in farm size varies from small land parcels (less than several hectares) to large farming operations (greater than 5000

The study area's population is low, with 223,000 persons. To estimate the values of the agriculture production, the annual crop production by county [9] was multiplied by commodity prices for that time [9]. The annual value of the agriculture production from cropping systems is \$1.27 billion (2016). The five-year (2012–2016) average value of production for the dominant crops include: (i) corn (\$325 million) and (ii) soybeans (\$525 million), cotton (\$200 million), rice (\$150 million), and wheat (\$75 million). For the same five-year period, the mean crop yields are (i) corn (8844 kg/ha), (ii) soybeans (2722 kg/ha), cotton (1177 kg/ha), rice (7706 kg/ha),

To estimate the agribusiness sales of production inputs, the product of the county harvested acreages [9] and the University Missouri crop budgets [10] were utilized. The profitability of the agribusiness sector includes: (i) seed sales for corn (\$47.38 million), soybeans (\$77.94 million), wheat (\$7.88 million), cotton (\$29.52 million), and rice (\$5.25 million), (ii) fertilizer sales for corn (\$57.8 million), soybeans (\$51.5 million), wheat (\$14 million), cotton (\$17.6 million), and rice (\$19.8 million), and (iii) herbicide sales for corn (\$14.1 million), soybeans (\$44.3 million),

The Mississippi River embayment was initially created by an ancient down warping of the crust, presumably by tectonic forces. Confining our discussion to the Pleistocene-Holocene the ancestral Mississippi River occupied an Advance Lowland course until the late Wisconsin sub-stage [6, 11, 12]. These authors proposed that the diversion of the Mississippi River through the Bell City—Oran Gap, abandoning the Advance Lowlands and entering the Morehouse Lowlands, was initiated approximately 17,000 year BCE (before common era) and was complete by 11,500 year BCE. By 9800–9900 year BCE, the Mississippi River changed from a braided river to meandering river, passing through the Pemiscot Bayou [12]. After the diversion, the advance lowlands continued to receive sediment from the Ozark Plateau, principally from the Little Black River, the Current River, the Spring River, and the White River. Blum et al. [13] proposed that the Bell City—Oran Gap diversion into the Morehouse Lowlands occurred before 60,000 year BCE, thus placing the Bell City—Oran Gap diversion before the Wisconsin glaciation. Royall et al. [12] proposed that the Ohio River produced two braided stream terraces in the Morehouse Lowlands between Crowley's Ridge and Sikeston Ridge.

wheat (\$5.6 million), cotton (\$14.5 million), and rice (\$16.1 million).

**9. The geological history of the study area**

beef cattle and horse operations.

158 Wetlands Management - Assessing Risk and Sustainable Solutions

hectares) [9].

and wheat (3965 kg/ha).

Approximately 9000 year BCE, the Mississippi River diverted through Thebes Gap and flowed east of Sikeston Ridge [12], creating the Charleston Alluvial Fan. The study area has been extensively modified by seismic activity, featuring sand blows, sand boils, clastic dikes, liquefaction, changes in stream drainages, and subsidence [14–16]. A prominent trend of earthquake epicenters has been related to deep-seated folds and igneous intrusions [16]. Loess deposition as a capping on soils in the advance lowlands shows both the stage of development and bisequal nature of these soils [17].
