This study uses spectral decomposition of GPR data to recognize tuning in a wedge of unconsolidated alluvial sediments. It also compares the spectral decomposition analysis to the results of more traditional attributes such as instantaneous frequency. The study area is on the northern bank of the Canadian River, south of Norman, Oklahoma, USA. (Figure 1). The alluvium ranges in thickness from approximately 10 to 15 m and is mostly sand, with varying amounts of silt and clay and rare occurrences of gravel. Underlying the alluvium is the Hennessey Shale.