Radioactivity of the granitic soils in the middle district of tottori prefecture

The greater part of the middle district of Tottori Prefecture is formed of biotite granite, hornblende andesite, augite andesite and hornblende andesitic volcanic detritus. The granite occurs in the region streching to the north-east from the border between both Tottori and Okayama Prefecture. In this granite area, there can be seen many dikes of aplite and micropegmatite. These granitic rocks, and the soils derived from them have higher radioactivity than other rocks and soils. In this district, there are radioactive hot springs-Sekigane, Misasa, Shikano and Hamamura, and, recently uranium ore was found at Ogamo and Ningyotoge. A study was made on the radioactivity of the soils derived from the granitic rocks, andesite and tertiary shale, of the ashes from plants grown on these soils, and on the extraction of thorium X in the soils.