四川盆地西部晚三叠世地层发育,层位齐全,最厚达三千余米。但晚三叠世早期(卡尼期)地层,分布比较局限。1959年全国第一届地层会议上,把朱森(1942)创立的天井山灰岩作为卡尼阶。因未发现重要化石,许多单位把天井山灰岩划归拉丁阶,与贵州法郎组对比,认为普遍缺失中、晚三叠世之间的地层。1966年王迺文等据有孔虫化 The Late Triassic strata in the western Sichuan Basin developed with complete layers and the thickest reaches over 3,000 meters. However, the late Triassic (Carnian) strata, the distribution is more limited. In 1959, at the first strata conference in China, the Paleishan limestone founded by Jusen (1942) was taken as the Carney order. Because no important fossils were found, many units placed the Paleishan limestone in the Latin order. Compared with the Guizhou FF group, many units believed that the strata between Middle and Late Triassic were generally missing. Wang Wei Wen in 1966, according to the hole worm