Surface morphology and stratigraphy suggest that the fans have
Sediment for equivalent dose (De) estimate is most often collected by pounding a metal tube into a sand lens then removing it to retain an intact core of light-protected material. If the deposit is too compacted or cemented for a metal tube, it may be possible to remove a block of cohesive ASC-J9 and use the inner, light-protected sediment for De estimation. For dose-rate calculation a sample is collected from sediment within a ∼30 cm radius around the sample tube or block. Ideally, samples are collected from sand lenses >60 cm thick and wide where it is reasonable to assume a homogenous beta dose-rate environment. Coarse-grained fluvial environments often lack thick sand lenses, if present at all, and are often not cohesive enough to allow removal of a block of sediment. In these cases, a modified sampling strategy is required, such as collection of bulk sediment samples at night or under light-proof tarps (e.g. Rizza et al., 2011).
2. Regional setting
The LRR lies within the northeastern extent of the Basin and Range Province of the western USA in east-central Idaho (Fig. 1). Relief of the LRR has resulted from movement along the Lost River Fault, a west-dipping normal fault that bounds the western flank of the mountain range. Bedrock is primarily Precambrian and Paleozoic limestones and quartzarenites (Haller and Crone, 2004 and Skipp and Hait, 1977).