Soil tongues, or soil fingers, have been identified along the walls of an active gravel pit in northeastern Indiana. Locally enhanced pedogenesis, primarily carbonate leaching and clay illuviation, has resulted in wedge- and cone-shaped extensions of the B horizon into the underlying calcareous glaciofluvial sediments. Although previously described in the literature, the features at this site are considered unusual both for the numerous well-defined tongues and for the regularity of tongue spacing, which gives the illuviation front the appearance of a high-amplitude sinusoidal wave train. Depth to the illuviation front was measured at 0.25-m intervals along a 40-m exposure. Statistical tests indicate that the spatial pattern is nonrandom. The data were transformed using Fourier methods, and the resulting variance spectrum show a peak intensity at wavelengths bracketing 1.5 m. The results of these analyses suggest a surficial or near-surface topographic control. Climatic conditions following local glacier recession favored periglacial activity, and there is some evidence to suggest development of thermal contraction cracks and nonsorted or poorly sorted polygons 1.5 m in diameter. As an alternative hypothesis, laboratory experiments suggest that regularly spaced fingers can develop in homogeneous materials when instability occurs at the wetting front. In this case, soil tongues cannot be used as relict indicators of periglacial activity.