Gamma-ray spectrometry is a passive remote sensing technique that measures the natural emission of gamma-ray radiation in the upper 0.3 m of the earth's surface. The technique estimates the abundances of potassium (K), thorium (Th) and uranium (U) via the gamma-ray emitting isotopes of the 40K, 232Th and 238U decay series, respectively. Conventionally, gamma-ray surveys are conducted using either low flying aircraft (e.g. regional surveys), or on foot/vehicle mounted (e.g. field and catchment surveys).Earth surface gamma-ray emissions relate strongly to the mineralogy and geochemistry of the bedrock and weathered materials (e.g. soils, saprolite, alluvial and colluvial sediments). The imagery generated can thus be regarded as surface geochemical maps of the distribution of rock, regolith and soil radionuclides. Where the bedrock contains K-bearing minerals, the loss of K in the soil can often be used as a surrogate for mapping the degree of surface weathering and leaching. Potassium is also associated with potassic clays such as illite, and in smaller amounts incorporated in the structure of clays (e.g. montmorillonite and kaolinite). In contrast, U and Th are often associated with more stable weathered constitutes in the soil profile. Uranium and Th released during weathering are readily adsorbed to clay minerals, oxides (Fe and Al) and soil organic matter. Elevated U and Th can also be associated with resistate minerals. For the reasons discussed, Th and U concentrations often increase as K decreases during bedrock weathering and soil formation. In erosional landscapes the gamma-ray response strongly relates to the bedrock mineralogy and geochemistry, weathering history, and contemporary and ancient landscape processes. Soil gamma-ray responses in depositional landscapes reflect the geochemistry and mineralogy of the source rock (or regolith) from which the sediments are derived, and the post-depositional sorting and weathering processes. In both erosional and depositional landscapes, when the radioelement characteristic of the sources are well understood, gamma-ray data can be used to predict specific soil characteristics and provide information about erosional, depositional and weathering processes.This paper presents Australian case studies that feature the use of regional and field scale gamma-ray surveys as part of investigations to support prudent land use in upland saline landscapes. These case studies highlight the importance of integrating with the gamma-ray imagery auxiliary datasets (e.g. digital elevation models, soil and regolith electromagnetic conductivity, soil and geological mapping) to enhance the quality of soil-regolith information generated as part of the investigations. Soil-regolith information generated through these methods include new knowledge of weathering histories, soil types and landscape evolution, and the location of deep profile salt stores.