Thus there is good evidence of faunal and lithological com- parison with South China for the Pa Kae Forma- tion.This is continued with the overlying Wang Tong Formation, which marks a return to clastic deposition, and completes Ordovician sedimen- tation.The lower part is entirely graptolitic, but higher in the section at the top of the Ordovician there is a thin development of the latest Ordovi- cian Hirnantia fauna. including some seven brachiopod genera (making up 74% of the total abundance) and the typical trilobite Mucro- naspis mucronata (Cocks and Fortey, 1997). The Hirnantia fauna sensu lato is practically pandemic. It is associated with a widespread cli- matic decline more or less coincident with the end-Ordovician glaciation. However, at the spe-