A spectral signature has been constructed for an oxidized topsoil found in the vicinity of near-surface uranium deposits in porous, arkosic sandstones of the Wind River Basin, Wyoming. A new type of contour map, created from Landsat computer compatible tapes, designed to connect regions of equal percentage of ground area covered by a specified target of interest, was applied to a Landsat frame covering the entire basin. The resulting maps showed relatively high percentages of ground cover by this particular topsoil in regions adjacent to open pit uranium mines in the Gas Hills region, as well as on or near known uranium prospects (as yet undisturbed) in the basin interior. A 10,000-pixel test area west of Lander, Wyoming was found to contain only one pixel (a 0.01 percent recognition rate) identified as the topsoil of interest. However, a whole-frame recognition map produced a much higher (0.58 percent) recognition rate, indicating that the false alarm rate for this signature is still significantly high, although better than what can be expected from photointerpretation of single ratio images or color composite ratio images. This 'signature' has been applied to Landsat frames in other geographical areas with known uranium mines in porous sandstone, and oxidized topsoil has been recognized near these mines.