Phuket Series (Cambrian)
Beds of metamorphosed sedimentary rocks occupy a large region along the central axis and west side of the Peninsula and continue northward into lower Burma. In Thailand, the metasedimentary rocks extend northward from Phuket to the latitude of Ratchaburi and in the vicinity of granitic intrusions in the Khao Luang mountain chain of the eastern Peninsula.
The beds stand on edge in most localities, so that thickness and sequence cannot be determined. In railway cuts between Thungsong and Ronphibun many beds of fine sandstone are found interbedded with shale and gritty shale. Most exposures elsewhere are of dark, well-bedded schists, slate, quartzite, and argillite.
The only fossil locality now known in the Phuket series is at the northeast promontory of Thongka Harbor--Phuket Island, where "fucoidal" impressions were found in a dark gray shale or slate.