The ESR-signal intensity associated with the oxygen vacancy in the silt sized fine quartz and the clay mineral composition were examined, in order to investigate the influence of eolian dust on the parent materials in two Red-Yellow soils developed on the bedrock of Tertiary sediments and two Dark Red soils on the bedrock of the Tertiary Ryukyu limestone, in Yonaguni island. The results summarized as follow: In the A, Bw1 and BC horizon of a Red-Yellow soil, Kubura (KUB) soil, ESR-signal intensity of fine quartz in the silt fraction was above 10 and very high value, and suggested the influence of eolian dust brought from the Precambrian area in the southern part of China on the parent materials in this soil during MIS2. In two Dark Red soils, Sonai (SON) and South-meadow (MIN) soil, the ESR-signal intensities of silt sized fine quartz in the A and B horizon were also very high and suggested the eolian dust from Precambrian area in the southern part of China. On the other hand, the ESR-signal intensities of fine quartz in the A and B horizons in a Red-yellow soil, Urabu (URA) soil were slightly low and the parent materials in this soil were the mixture of eolian dust from the Precambrian area in the southern part in China and autochthonous Tertiary bedrock. The parent materials in four reddish soils developed on the Tertiary bedrock in Yonaguni island were derived from the eolian dust brought from the Precambrian area in southern part of China during MIS2, Last glacial Maximum. While a small amount of the autochthonous Tertiary materials were slightly mixed to the parent materials in these soils. This result obtained from the ESR-signal intensities of fine quartz were harmonized with the clay mineral composition in these soils.
