This dataset contains proportions of grain size classes, the median grain size, and the differential grain size distribution for the size fraction 40–311 nm of 32 soil samples sieved to <2 mm from 16 shallow soil profiles, which were sampled in two depth intervals (0–15 and 15–30 cm). Constituting a soil chronosequence at the south-central coast of the Atacama Desert, four shallow soil profiles were sampled from each of the four morphostratigraphic units of the coastal alluvial fan Paposo (25.03°S/70.47°W). Particle size measurements were conducted using laser diffraction analysis. Results are stored in a .csv table.