Figure F20. Paleomagnetic field secular variation (PSV) records. A. PSV for the last 2000 yr estimated from paleomagnetic studies of lake sediments in Argentina, dating based on bulk-radiocarbon dates. Data for the last 400 yr are the expected directional variability at the site of the lakes based on spherical harmonic analysis of other historical global field data (modified from Lund and Constable, unpubl. data). B. PSV recorded in Core 202-1233B-1H. The chronology is derived by correlating magnetic susceptibility to nearby piston core GeoB3313-1, which has been dated by AMS-14C on planktonic foraminifers (Lamy et al., 2001). The distinctive inclination and declination features (labeled I1-I2 and D1-D4) can be correlated to similar PSV features in A.