The deposition of aeolian (windblown) dust is a global phenomenon with significant implications for terrestrial ecosystems. In particular, the geochemical flux of dust can be an important factor for biogeochemical cycling in soils and, in some settings, may influence ecosystem productivity and chemical weathering. To quantify the role of exogenous dust in soils, the flux and composition of dust must be compared with local soil forming factors. In general, the magnitude, particle size, and geochemical composition of dust vary regionally and are primarily dependent on the distance from dust source area. Each winter/spring the San Juan Mountains (SJM) receive a substantial flux of exogenous dust, which most likely originates form the [...]