Abstract: Abstract: In the paper the authors describe the features of a suite of clastic rocks and sedimentary-pyroclastic rocks and discuss the stratigraphic division and age assignment of the stratigraphic units on the north side of the Chengfang deep fault in the Daba Mountain area in the South Qinling. According to the lithological characteristics and contact relationships with the overlying and underlying strata, this suite is divided in descending order into the lower Sinian Muzhuo Formation and Dai'anhe Formation and the pre-Sinian Longtanhe Formation.