In October 2019, five marsh push cores (core names appended with M for marsh push core) and 18 surface sediment samples (top 1 cm of sediment) were collected from the estuary (sample name appended G for PONAR grab) near the mouth of the St. Marks River and some of the surrounding marshes (sample name appended with S for surface), along with elevation transects and peat augers (sample name appended with R or R50, depending on length, for Russian peat auger). The purpose of the study was to 1) evaluate peat thickness relative to the shoreline and upland, 2) compare marsh accretion rates with other marshes along the northern Gulf of Mexico, 3) determine whether sea-level or storm history records are recorded and viable, and 4) compare elevation and shoreline data with post-Michael lidar imagery. Cores and surficial sediment samples were processed and analyzed for organic content and grain-size. Cores and select surface samples were analyzed using gamma spectroscopy for determination of background and excess lead-210 with cesium-137, while the modern foraminiferal microfossil assemblage was determined using surface sediment samples. Foraminiferal samples (appended with F for foraminifera) were collected at surface sample sites and stained in the field with rose Bengal for determination of live (stained) and dead (unstained) microfossils. All samples in the dataset are referred to by field activity number (FAN) 2019-366-FA (alternate FAN 19CCT05) and are part of the U.S. Geological Survey St. Petersburg Coastal and Marine Science Center's (USGS-SPCMSC) Estuarine and MaRsh Geology (EMRG) research project, which works to understand how and where short- and long-term marsh and estuarine coastal processes interact, how they influence coastal accretion or erosion, and how they pre-condition a marsh’s resiliency to storms, sea-level change, and human alterations along the northern Gulf of Mexico.