The Amphibole-Schist Series appears to be confined to Malaya east of the Main Range, and it is most abundantly developed in north-west Pahang. It occurs partly in the Main Range Foothills, partly between them and the Main Range granite in the Sua-Kerla-Kelubi-Tempoi river system of the Telom Valley, in the Jelai Kechil valley, in the Sungei Lipis and in the Chembatu-Batu-Cheroh system between Batu Malim and Cheroh, Raub District. So far as is known these crystalline schists do not extend far northwards into Kelantan, and they are likewise but poorly developed south of Pahang in Negri Sembilan. They are everywhere associated with the Arenaceous Formation of the Main Range Foothills, quartzites, quartzite-conglomerates, shales, cherts, phyllites, quartz- and mica-schists, which may be either Triassic according to Scrivenor (1911, 1931) or perhaps older than the adjacent Permocarboniferous shales and limestones according to Service, Alexander, and the writer (Ann. Rep., 1940, para. 39; 1939, 1946). In some areas they lie partly on the Main Range granite (Text-fig. 1).