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Stratigraphic distribution. Abundances of spherules by site (red lines), plotted on lower x axis in number per kilogram relative to the YDB depth at 0 cm. SLO concentrations (black lines) are plotted on upper x axis in grams per kilogram (SI Appendix, Table S3). Thickness of sample containing YDB is indicated by blue bar. Dates for YDB layer are in blue, as determined by age-depth models (SI Appendix, Table S1).
