**6. Landforms and vegetation**

Much of the natural vegetation has been removed and replaced with agricultural enterprises. Depressional areas consisting of backswamp deposits typically supported bald cypress (*Taxodium distichum* L.), water tupelo (*Nyssa sylvatica*), sweetgum (*Liquidambar styraciflua* L.), and multiple species of canes, rushes, and grasses, whereas recent meander belt deposits have willows (Salicaceae sp.), eastern cottonwoods (*Populus deltoides* Marsh.), American elm (*Ulmus americana* L.), yellow poplar (*Liriodendron tulipifera* L.), and boxelder (*Acer negundo* L.). Mixed forest species existed on well-drained to moderately well drained soils residing on variably textured alluvium and natural levees. Mixed forest species included: southern red oak (*Quercus falcata* L.), willow oak (*Quercus phellos*), white oak (*Quercus alba* L.), swamp white oak (*Quercus bicolor* Willd.), and shagbark hickory (*Carya ovata* Mill.).

The Southeast Lowlands Groundwater Province (SLGP) is bounded on the north and west by the Ozark Plateau, with the transition from the SLGP to the Ozark Plateau called the Ozark escarpment. The eastern boundary is the modern Mississippi River and the southern boundary is the Missouri-Arkansas state border. The western boundary of Dunklin Co. is the St. Francois River (**Figure 1**).

A prominent ridge within the SLGP is called Crowley's Ridge and the Benton Hills. These elevated land masses consist on Paleozoic rocks, largely Ordovician, and are covered by Tertiary gravels and loess [6]. Crowley's Ridge and the Benton Hills bisect the SLGP, with the land mass between Ozark Escarpment and west of Crowley's Ridge and the Benton Hills called the Advance Lowlands (also called Western Morehouse Lowlands). The Advance Lowlands represent the ancestral channel of the Mississippi River and are generally composed of loamy to silty terraces and back-swamp deposits overlying glacial outwash and valley train. Conversely, the Morehouse Lowlands extend from Crowley's Ridge eastward to the Mississippi River. The Morehouse lowlands consist of terraces of varying textures, back-swamp deposits, and other alluvial environments overlying braided glacial outwash. The modern Mississippi River and its flood plain is the youngest and easternmost feature with meandering channel deposits, natural levees, silty terraces, back-swamp environments, and crevasse splay deposits that characterize the Mississippi River floodplain [7]. Sikeston Ridge and Barnes Ridge (east of Portageville, MO) are low-elevation ridges, composed of coarse-textured materials and both are in the Morehouse Lowlands. Just east of Crowley's Ridge and extending into Dunkin Co. is a terrace system of coarse-texture materials called the Kennett-Malden Prairie. The Charleston Lowland is located primarily in Mississippi Co. and consists of fine to coarse textured materials, composed to recent terrace and back-swamp environments. Between the Benton Hills and the Charleston Lowlands is the Blodgett terrace composed of coarse-textured materials and the Charleston Fan, also composed of coarse-textured materials.
