二十世纪中叶以后，中、美寒武纪地层研究都有重大进展。三叶虫是寒武纪的重要化石，中、晚寒武世牙形石有显著的生物地层意义。二十世纪中叶国内研究寒武系的学者，认为北美寒武系与西欧及北欧的相似，与中国的差异较大。目前看来，北美东部斜坡相区的寒武系与西欧、北欧相似外，北美西部广大地区(包括阿拉斯加、加拿大及美国境内的落基山等地区)，分别与西伯利亚，蒙古西北部一些地区，及我国华北、东北南部及华南等地区的寒武系关系较近。北美西部Nevada及Utah等地也显示地台区及斜坡相区的不同。文内对两个地区早、中、晚寒武世地层内相同的属或种，分别进行对比。两地区属种相同的数目，由老到新逐渐增多。岩石方面，也有相似之处，如Pioche页岩和馒头组的岩性，Notch Peak灰岩与凤山组藻类灰岩及Hales灰岩与华北晚寒武世的竹叶状灰岩等，都有相似之处。

Division of the Cambrian System into lower, middle and upper series was first suggested by Walcott(1891a,b) and has been followed by all subsequent workers. A stage classification has been proposed only for the Upper Cambrian of North America (Howell and others, 1944), based on the formational succession of the Minnesota Wisconsin region (Lochman Balk, 1971). Recently 4 new series and 6 new stages names for the Cambrian of Laurentia have been established by American and Canadian authors (Ludvigsen and Westrop, 1985; Palmer, 1998). The classical Middle and Upper Cambrian sequence for China is in Shandong, where is the type area for the establishment of the Middle and Upper Cambrian stages of China (Lu and Dong, 1952; Lu, 1962). Because the Lower Cambrian deposits in Shandong is incomplete,stage subdivisions have been proposed with those of eastern Yunnan in the Lower Cambrian (Lu, 1941,1962). In the first synthesis of North American and Chinese Cambrian biostratigraphy (Howell et al. ,1944; Lu, 1962), much of the present biostratigraphic framework on both sides of the Pacific was established. During the last 50 years, many publications concerning Cambrian trilobite faunas, biostratigraphic studies as well as ecological analysis of Cambrian trilobite distribution based on tectonic setting by both American and Chinese palaeontologists, have increased our knowledge and understanding of the Cambrian biostratigraphic correlation between North America and China (Chang and Jell, 1987; Jegorova et al., 1963;Kurtz, 1981; Lochman Balk and Wilson, 1958; Lochman Balk,1970,1974;Lu et al., 1974;Nogami, 1966; Palmer, 1965,1966,1971,1977,1981,1982;Palmer and Halley,1979;Palmer and Peel, 1979; Robison, 1976; Saito, 1933, 1934;Shergold and Nicoll, 1992;Shergold, 1993;Sundberg and McCollum, 1997). Based on these more recent palaeontological studies, it now seems possible to improve Cambrian correlation between China and North America made by different authors since 1937 (Endo, In Endo and Resser, 1937; Howell, 1947; Chang, 1957, 1986; Lu, 1962; Shergold, Laurie and Sun, 1990; Shergold, 1997; Peng, 1992).

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ThisworkwassupportedbygrantsfromtheMajorBasicResearchProjectsoftheMinistryofScienceandTechnology China (G2 0 0 0 0 7770 0 )