Masuda-Misumi distict occupies the Sanin branch of the Sangun metamorphic belt which is the most extensive regional metamorphic belt in the inner zone of southwest Japan. In this district, various kinds of low grade metamorphic rocks such as pelitic schist, siliceous schist, psammitic schist and greenschist derived from the Upper paleozoic geosynclinal deposits are distributed continuously from Misumi-cho to Masuda-shi. The Sangun metamorphic rocks of this district are grouped stratigraphically into three groups. They are summarised as following table