Grain-size analyses of sediment cores from the Currituck Landslide Complex and upper slope adjacent to Baltimore Canyon collected on USGS Field Activity 2012-007-FA

Each core was cut into sections on the ship during collection. The cores were then split into halves in the core lab. Subsamples (1- cm thick) were taken from the split cores for grain-size analysis.

Samples submitted to the sediment analysis laboratory for grain-size analysis using the Beckman Coulter Multisizer3 and sieving of the ≥ 4 phi fraction are assigned internal analysis identifiers to record the measurement data. About 50 grams of wet sediment are placed in a pre-weighed beaker, weighed, oven dried at 100°C, and reweighed to correct for salt. The dried sample is wet sieved through a 0.062 mm (No. 230) sieve. The coarse fraction remaining in the sieve is oven dried at 100°C (until completely dried) and weighed. The fine fraction in water is collected in a plastic Nalgene bottle and sealed with a screw lid (stored for no longer than one week). The coarse fraction is dry sieved to determine the individual weights of the 4 to -5 phi fractions, and the weights are recorded in the data entry spreadsheet. At the request of the submitter, shell and shell fragments can be manually removed from the -2 phi and coarser fractions, weighed and their weights are recorded in the data entry spreadsheet. The fine fraction is run and combined using the 200 μm and 30 μm Coulter analyses using the Multisizer3 software (version 3.53) to get the fine fraction grain-size distribution. The fine fraction distribution data are added to the data entry spreadsheet. The spreadsheet is used to calculate a continuous phi class distribution from the original fractions.

Continuous phi class distribution from the original fractions are transposed to the "results" tab in the macro-enabled Microsoft Excel data entry workbook with a unique identifier assigned to the sample submission. Macros in the workbook are run to calculate grain-size classification and statistical analyses. Sample, navigation, and field identifiers, along with continuous phi class distribution data, grain-size classification, and statistical analysis results are copied and pasted into a final Microsoft Excel spreadsheet for each sample submission batch. The processed data are quality control checked and assigned a quality grade based on the examination of the analytical data. Processed data are released to the submitter and incorporated into the laboratory's database. All raw analytical data generated by the samples are archived in the sediment analysis laboratory.