摘要
NOT until Gao Zhenzhong and Eriksson studied the Ordovician of Fincastle area, Appalachi-ans, the USA in 1990, did sedimentologist recognize internal-tide deposits in the ancientrecord and begin to use the term of 'internal-tide deposit'. In the Ordovician of Fincastlearea, two facies are recognized: (i) bidirectional cross-laminated very fine grained