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Sediments recovered during Expedition 302 were sampled at BCR by the U-channel method for paleomagnetic and environmental magnetic studies. All sections were sampled except those that were obviously severely disturbed by drilling (e.g., flow-in or slurry).

The details of the U-channel sampling method are shown in Figure F10. The first step is to press or implant the U-channel into the core section (Fig. F10A). For lithologic Subunits 1/1 and 1/2, this implant was done by hand, whereas for Subunits 1/3, 1/4, and 1/5, a spatula was used to cut slots along the sides of the U-channel, and then the U-channel was driven into the core section with small mallets. Finally, for lithologic Subunit 1/6 and Units 2 and 3, the sections were marked, slots were cut using a cast-cutter saw, and the U-channel was driven into the slots using hand mallets.

Removal of the U-channel was achieved by a similar method that involved making a bottom cut using a range of cutting implements. The cutting implement used for the bottom cut depended on the stiffness of the material sampled. Cutters with a U cross-section were used for lithologic Subunits 1/1 and 1/2, whereas a spring-wire cutter was used for Subunit 1/3 through Unit 3. Most U-channels were lifted directly out of the core sections after the bottom cut was made. U-channels from wet, sticky, or crumbly lithologies were removed by inserting the core sections into an open-ended D-tube with a slot cut down the middle of the upper surface. The D-tube containing the core section was turned upside down (Fig. F10B), and the U-channel was pulled from the section using gravity as an aid (Fig. F10C).