The mineralogy and geochronology of silt fractions were determined for a representative Andisol (volcanic soil) from the Mt. Daisen area as well as for collected bulk reference fallout materials from Japan, and Kyoto dust samples. X-ray diffraction techniques and K-Ar methods were used to determine the age values and mineralogy of test materials. The reference fallout material was the youngest (21 Ma). The Kyoto dust was oldest (210 Ma) of all materials. The silt from the Andisol yielded older age values closer to the top and younger values closer to the parent tephra. The silt mineralogy revealed small amounts of 10 Å and 14 Å phases. The presence of these phases in the silt fractions of soils having parent dactic-basaltic tephra (Ma) combined with the geochronology ages of the silt fraction (21 – 210 Ma) support the hypothesis that there is an aeolian influence present in the Andisol.