The Longmaxi formation of Lower Silurian is ten metres in thickness,containing three graptolite zones:Glyptograptus persculptus,Parakidograptus acuminatus and Orthograptus vosiculosus.

• 下志留统龙马溪组厚10m；含Glyptograptus persculptus；Parakidograptus acuminatus及Orthograptus vosiculosus三个笔石带.