The Middle-Upper Cambrian in the Jiawang area is represented by the Erlangshan section. It is exposed more completely from the Zhangxia Formation to Fengshan Formation. The bottom boundary is an exposed surface at the top of red sandstone of the Xuzhuang Formation (SB2) and the top boundary is the Sanshanzi dolomite (s. s. ) of the Fengshan Formation (SB2). The section includes the following three different characteristic sequences; (1) the Zhangxia sequence (DSD , which corresponds with the Zhangxia Formation, characterised by ooid shoals and great algal built with various branched algae; (2) the Gushan sequence (DS2), which corresponds with the Gushan Formation, characterised by episodic deposits-debries flows, basin micrite and allochthonous oolitic limestone with cross beddings; (3) the Changshan-Fengshan sequence (DS3), which corresponds with the Changshan and Fengshan Formations, characterised by volute autochonous edgewise limestone, dolomized thick-bedded stromatolithic limestone and dolomite (Sanshanzi dolomite s. s. ). Of them, algal reefs in the Zhangxia sequence are the greatest carbonate ramp algal reef of the Middle-Upper Cambrian, the condensed section in the Gushan sequence is the maximum seaflood surface in the Middle-Upper Cambrian which respre-sents the highest sea level, dolomite on the top of the Changshan-Fengshan sequence respre-sents deposits in the period of the lowest sea level during the Middle-Upper Cambrian.