Ⅰ. INTRODUCTION During the geological reconnaissance in E Sikang in 1941-1942 the writers observed an old acid volcanic series, together with related intrusive rocks, in the southeastern part of the province, mainly in the valley of the Tatuho (Tungho)~1. In 1930, the extrusive rocks of this valley between Tsutati (Anshunchang)~2 and Chinkouho~3