This data release is an archive of sedimentary field and laboratory analytical data collected in Grand Bay, Alabama/Mississippi from 2014-2016 by scientists from the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center (USGS SPCMSC). This work, a component of the SPCMSC’s Sea-level and Storm Impacts on Estuarine Environments and Shorelines (SSIEES) project, provides the necessary data to quantify sedimentation rates and sediment sources for the marsh and estuary. The SSIEES project objective is to evaluate the exchange of sediment material between the marsh and estuary due to extreme storms and sea-level rise. Micropaleontological data from select cores and surface samples are available in Haller and others (2018, https://doi.org/10.5066/F7MC8X5F, https://doi.org/10.5066/F7445KSG). Single-beam bathymetry of Grand Bay proper and multi-beam bathymetry of several marsh-edge eroding shorelines are reported in Dewitt and others (2017, https://doi.org/10.3133/ds1070) and Stalk and others (2018, https://doi.org/10.5066/F7MC8Z9N), respectively. Subbottom and sidescan sonar data for Grand Bay proper are reported in Locker and others (2018, https://doi.org/10.5066/P9374DKQ). This publication includes data for the sediment cores and surface sediments taken in Grand Bay marsh and estuary during five sampling periods of this study, which were designated as USGS Field Activity Numbers (FAN) 2014-323-FA (project ID 14CCT01), 2015-315-FA (project ID 15CCT02), 2016-331-FA (project ID 16CCT03), 2016-348-FA (project ID 16CCT04), and 2016-358-FA (project ID 16CCT07). Data products include: GPS-derived site locations and elevations; core photographs, logs, and x-radiographs; lithologic, radiochemical, elemental composition, stable isotopic composition, and radiocarbon data; and Federal Geographic Data Committee (FGDC) metadata.