Figure F12. Magnetostratigraphy and characteristic directions of Eocene–Cretaceous of Holes 1258A and 1258B based on shore-based analysis of minicores. The minicore data from the two holes have been merged using composite depth scales from each hole, and these adjustments are shown schematically by offset mbsf columns for each hole (rightmost columns). Polarity ratings are graded according to reliability and number of vectors utilized in the characteristic direction. R = reliable reversed polarity, INT = indeterminate, N = reliable normal polarity) (and relative placement of other points indicates degree of precision or uncertainty). Methods of polarity interpretation, polarity ratings, and derivation of characteristic inclinations and intensities are in "Paleomagnetism" in the "Explanatory Notes" chapter. Polarity zones are assigned according to clusters of individual polarity interpretations. Normal polarity zones = dark gray; reversed polarity zones = white; uncertain polarity or gaps in data coverage = cross hatched. Assignments of polarity chrons are based on the polarity zone pattern and the constraints from microfossil biostratigraphy. F = foraminifer, N = nannofossil.