This paper considers characteristics of plane‐wave reflection loss for a model of the ocean’s sub‐bottom consisting of a single inhomogeneous fluid layer (sediment) overlying a semi‐infinite solid (basement). It is found by direct computation that, under certain conditions of sediment sound speed gradient, density, and compressional‐wave speed ratios and attenuations, a large peak in bottom loss can occur over a narrow range of grazing angles. These angles occur below the shear and compressional wave critical angles; hence, they are not directly related to transport of energy by these wave fields. It is found, however, that the presence of shear waves in the substrate is necessary for such a peak to occur; that is, if the shear‐wave speed is set to zero in the substrate, the anomalous loss peak vanishes. Furthermore, these loss peaks are due to absorption rather than the transport of energy to infinity as evidence by the fact that, when all absorptions vanish, so do the anomalous peaks in bottom loss. The decay of pressure amplitude away from the sediment–substrate interface in both directions (for grazing angles in the neighborhood of the loss peak angles) suggests the presence of a surface or interface wave.