The sediment records of the Brunhes-Matuyama (B-M) transition and the upper Jaramillo were obtained from ODP Leg 167. Site 1014 is located at 32º50´N, 119º60´W, in the Tanner Basin of the California Borderland (Fig. 1). San Diego is ~290 km east of the location. In the upper 120 m below seafloor (mbsf), the sediments consist of clay and nannofossil ooze. The sedimentation rate in this part of the section is around 8 cm/k.y. (Lyle, Koizumi, Richter, et al., 1997). The B-M transition was sampled continuously with 1.5-m-long u-channels (2 × 2 cm2 in cross section) and with discrete samples at a spacing of 3 cm across the transition. The u-channels were taken from the archive halves and the single samples from the corresponding working halves of the cores at Sites 1014 and 1020.
Hole 1020C is located at 41º00´N, 126º26´W, on the east flank of the Gorda Ridge (Fig. 1). The sediments in the section where the B-M and the upper Jaramillo transition are recorded consist mainly of clay interbedded with nannofossil clay. The B-M and the upper Jaramillo transition at Site 1020 were sampled with u-channels. Discrete samples were taken at high spatial resolution (one sample every 3 cm) from 75.3 to 78.1 mbsf across the B-M reversal and from 93.3 to 95.4 mbsf across the upper Jaramillo reversal. The sedimentation rate at Site 1020 over the sampled interval is again ~8 cm/k.y.