The Bølling-Allerød deglacial event is marked by high diatom productivity and opal deposition throughout the subarctic Pacific. To investigate the cause of this event, we quantified several productivity-related sedimentary parameters that reflect the near-surface biogeochemistry from the Integrated Ocean Drilling Program (IODP) Site 323-U1340 in the Bering Sea. Diatom slides were made at the Instituto Português do Mar e da Amosfera using the M2 cleaning and slide preparation methods described in Abrantes et al. (2005, doi:10.1016/j.dsr.2004.05.012), treated in glass jars with no centrifugation. Species were counted via visual identification of >300 specimens when possible at 1050x.