西北区志留纪笔石地层在1959年全国地层会议前后只有祁连山和大巴山作过系统工作,祁连山由中国科学院〔1〕建立了早志留世中晚期3个笔石带,大巴山卢衍豪<2>建立了早志留世早及中期6个带,霍世诚〔3〕则分为8个带。对于秦岭,在区测工作中采到一些笔石仅早志留世初期的可以定种,收在全国地层会议学术报告汇编里〔4〕。随着我国社会主义革命和建设的深入发展,特别是无产阶级文化大革命以来,加强了对 The Silurian petrographic strata in the northwestern area had only been systematically worked before and after the National Stratum Conference in 1959. Qilian Mountain was established by the Chinese Academy of Sciences [1] with three penoliths in the middle and late Early Silurian. > As early as the early Midwest and the establishment of six bands, Huo Shicheng 〔3〕 is divided into eight bands. For the Qinling Mountains, some penoliths have been collected in the regional survey dating back to the early years of the Early Zhiwu Period and can be planted in the compilation of academic reports of the National Stratigraphic Conference [4]. With the deepening of the socialist revolution and construction in our country, especially since the Great Proletarian Cultural Revolution,