We conducted detailed paleomagnetic measurements on the sedimentary sections recovered at Integrated Ocean Drilling Program (IODP) Sites U1403, U1408, U1409, and U1410 during Expedition 342 to update the shipboard magnetostratigraphy. The intervals with negative inclinations are more clearly defined than the shipboard results, and this result has allowed us to refine chron boundary depths. In most cases, the chron boundary depths determined in the present study are not substantially different from the shipboard ones (less than ~1 m), but some boundaries have large differences. We also identify some new reversal boundaries that could not be resolved on board. IntroductionIntegrated Ocean Drilling Program (IODP) Expedition 342 recovered ~5.4 km of hemipelagic sediment drifts from the J-Anomaly and Southeast Newfoundland Ridge in the northwest Atlantic, off the coast of Newfoundland. Routine shipboard measurements were used to develop magneto-and biostratigraphic age models (see the "Expedition 342 summary" chapter [Norris et al., 2014a]). The shipboard magnetostratigraphy was based on the measurement of natural remanent magnetization (NRM) of the archive-half cores after 20 mT alternating field (AF) demagnetization on a wide-bore superconducting rock magnetometer in a magnetically noisy laboratory environment. In the present study, we performed detailed shore-based paleomagnetic measurements on the sedimentary sections recovered at Sites U1403, U1408, U1409, and U1410 (Fig. F1) to test and improve the shipboard magnetostratigraphy. Methods and materialsU-channel samples (typically 1.5 m in length with a 2 cm × 2 cm cross section) were taken from the central part of the archive-half cores along the stratigraphic splice described in the "Expedition 342 summary" chapter (Norris et al., 2014a): 30-160 m core composite depth below seafloor (CCSF) for Site U1403, 18-166 m CCSF for Site U1408, 6-142 m CCSF for Site U1409, and 0-165 m CCSF for Site U1410. A total of 530 samples were collected from archive halves, and 133 samples were collected from working

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