ELECTRICAL RESISTIVITY INVESTIGATION OF SMALLIN CAVE, SOUTHWEST MISSOURI

Southwestern Missouri is located on the Springfield Plateau which mainly consists of Paleozoic carbonates and minor amounts of siliceous sediments. The dominant formation exposed in the area is the Mississippian Burlington-Keokuk Limestone which is nearly horizontal and susceptible to the formation of karst features such as sinkholes and caves. Near surface geophysical methods are useful in determining the location and nature of karst features, especially those that are not visible on the surface.

Smallin Cave is located southeast of Springfield, Missouri, near Ozark, within the Mississippian Burlington-Keokuk Limestone. The entrance to the cave is approximately 50 feet tall and 100 feet wide with approximately 3,000 feet of mapped cave passage but total extent of the cave is unknown. There is also a perennial stream that flows through and out of the cave. This study will attempt to determine the depth of the cave and other possible cave passages that have not previously been mapped.

In order to determine the depth of the cave and extent of cave passages, the electrical resistivity method will be used. The electrical resistivity method will be used to determine the depth and extent of the cave passages. A resistivity low would be expected if there is a sufficient amount or clay and/or water. Otherwise, if the open voids are large and dry enough, a resistivity high might be expected. A number of profiles will be collected perpendicular to the axis of the cave. Individual profiles will be modeled using a two-dimensional inversion method. When enough profiles are collected, three-dimensional modeling will then be performed. If resistivity lows are found, then induced polarization profiles will be collected to determine if the source is water or clay.