The geomagnetic polarity timescale for the Matuyama Chron. From left: (1) coupled K–Ar and paleomagneticstudies summarized by Mankinen and Dalrymple (1979); (2) ODP Site 677 and DSDP Site 607 (Shackleton et al., 1990) asadopted by Cande and Kent (1995); (3) 40Ar/39Ar and paleomagnetic studies of volcanics (summarized by Singer et al., 2004);(4) ODP Sites 980–984 (Channell and Kleiven, 2000; Channell et al., 2002, Channell and Guyodo, 2004).