THE ORIGIN AND EXTENT OF A PERCHED WETLAND, MILLSAPS COLLEGE, JACKSON, MS

The origin and extent of a perched wetland was investigated using historical topographic maps, hydrologic data, and dendrochronological techinques. The area of investigation is situated on a gradual slope yet supports black willow (Salix Nigra), soft rush (Juncus effusus), and cattail (Typha latifolia). Hydric soil development has also been documented. The water table elevation was determined using a network of shallow piezometers and a shallow well. Daily measurements made over several intervals throughout a 12-month period documented saturation of the root zone in excess of two weeks during the growing season. The analysis of annual ring increments from old-growth post and red oak trees (Quercus rubra, Quercus stellata) was also done to determine if there is a link between the death of several trees in recent years and increased soil moisture related to wetland formation. Based on successive topographic surveys over the past 44 years the perched condition appears to be related to the construction of a baseball field in the late 1970's. The grading of Pre-Loess Terrace deposits on the hilltop facilitated the drainage of water perched on top of the underlying Yazoo Clay. Pre-Loess Terrace sediment removed during ball field construction was used to re-contour the slope and fill in a drainage depression developed on top of the Yazoo Clay. The margin of the localized 0.5 ha wetland corresponds to the extent of the filled-in drainage. The area will be preserved as an outdoor laboratory and example of sustainable landscaping.