I. INTRODUCTION Bordering the SW margin of the Red Basin of Szechuan runs a roughly N-S mountain range which includes such mountains as Washan, Omeishan and Talliangshan (Pl. I) and for the sake of convenience is designated with the name of Liangshan Range. Among these mountains only the geology of the Omeishan region is fairly well known in consequence of the works done by many a geologist; of the Washan region, though had been visited by