SEDIMENT - GRAIN SIZE collected using a vibracorer from an airboat at a washover deposit near Port Fourchon in Coastal Waters of Louisiana from 2019-08-28 to 2019-08-28 (NCEI Accession 0276483)

Core 2A was subsampled downcore at various cm-scale intervals. Grain size analysis was conducted using a Beckmann–Coulter laser diffraction particle size analyzer (Model LS 13 320). This analyzer can measure particle sizes ranging from 0.02 to 2000 um, and the method of Xu et al. [2016] was used. About 1 g subsample from each slice was placed in a centrifuge tube, and 10–20 milliliters of 30% hydrogen peroxide was added. The samples were left on a hot plate set to 70 degree C for up to 12 hours to oxidize any organic matter. The samples were then rinsed with deionized water to remove any leftover particles, centrifuged to separate sediment from water, and disaggregated using a Vortex mixer. After that, the samples were placed into the laser analyzer for measurement. The percentages of sand (>63 um; phi < 4), silt (4–63 um; phi is 4–8) and clay (<4 um; phi > 8) were determined. Median grain size (D50) was calculated in both um and phi. Depths of core 2A are in cm.