We present a magnetostratigraphic record from the western Philippine Sea that is tied to a marine δ18O record for
the past 2.14 million years. The ages of geomagnetic reversals were astronomically calibrated by tuning the oxygen
isotopic stratigraphy, yielding a chronology for the following subchrons: Matuyama/Brunhes boundary, 781±3 ka
(slightly above δ18O Stage 19.3); top of the Santa Rosa polarity interval, 920 ± 2 ka (Stage 23/24); base of the
Santa Rosa polarity interval, 925 ± 1 ka (Stage 24); top of the Jaramillo subchron, 988 ± 3 ka (Stage 27); base of
the Jaramillo subchron, 1072 ± 2 ka (Stage 31); top of the Cobb Mountain subchron, 1173 ± 4 ka (Stage 35/36);
base of the Cobb Mountain subchron, 1185 ± 5 ka (Stage 36); top of the Olduvai subchron, 1778 ± 3 ka (Stage
63/64); base of the Olduvai subchron, 1945 ± 4 ka (Stage 71/72); top of the R´eunion II subchron, 2118 ± 3 ka
(Stage 80/81); and base of the R´eunion II subchron, 2133 ± 5 ka (Stage 81). This astronomically calibrated
chronology independently confirms the ages of major reversals in recently published astronomically calibrated
polarity timescales for the Matuyama chron. It also provides the first astronomically calibrated dates for the lower
and upper reversals associated with the Cobb Mountain and Santa Rosa polarity intervals, respectively.
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