As shown in Fig. 3 the Kaeng Krachan Group is the stratigraphic unit which shows the pronounced difference between the Phuket Terrane and the adjacent block. In the Phuket Terrane several attempts have been made to subdivide it into component formations (Piyasin, 1975; Raksaskulwong and Wongwanich, 1993; Chaodumrong et al., 2007).