In 2012,the author worked in Bangor West 1:50000 regional geological survey,based on the rock combination features and graptolite fossils in the Sangri Profile PM5,divided original Dewuka lower Group into two sections.The hypomere is mainly graptolite silt sand facies.The upper is mainly middle bioclastic powder crystal limestone and celadon,olivine,tawny thin siltstone interbedded.The lower is mainly graptolite silt lithofacies.The graptolite fossils which obtained from lower graptolite siltstone layers,was identified species of Monograptus sp,Early Silurian.