Processed results from of surface grain size analysis of the sediment grab samples recovered as part of the Long Island Sound mapping project Phase II.

Sediment grab samples have been taken in summer of 2017 and 2018 using a modified van Veen grab sampler. A sub-sample of the top two centimeter was taken and stored in a jar. Dried sub-samples samples were analyzed for grain size. First the samples were treated with hydroperoxide to remove organic components. Then the sample was passed through a series of standard sieves representing Phi sizes with the smallest being 64 µm. The content of each sieve was dried and weight. If there was sufficient fine material (< 64 µm), then this fine fraction was further analyzed using a Sedigraph system. The results of sieving and sedigraph analysis have been combined and the percentages for gravel, sand, silt and clay are determined following the Wentworth scale. In addition, other statistics including mean, median, skewness and standard deviation are calculated using the USGS GSSTAT program.

The results of the LDEO/Queens College grain size analysis have been combined with data collected by the LISMARC group and analyzed by USGS. Based on the different percentages sediment classifications are determined following the Schlee and the Falk systems. These results are also translated into the CMACS systems. The data are presented as Excel spreadsheet and ESRI shapefile.

Time period of content: 2017-08-01 to 2022-11-16

Attribute accuracy: The attribute accuracy has not been determined, but standard practices have been followed.

Completeness: The dataset is mostly complete. Several samples had too little material to perform analyze the fine fraction in the sedigraph. The fines of these are distributed over the fine grain scale. These samples are dominated by sand and/or gravel and, therefore, the remaining fines do not really influence the classification.

Positional accuracy: Locations are based on DGPS using the ship GPS antenna for most cores resulting +/- 5 m accuracy.

Attributes:

Sample_ID: Text describing the Name of the grab sample

Lab: Text indicating if the sample was analyzed at the LDEO core Lab, Queens College, or by USGS

Project: indicating the phase of the Long Island Sound Mapping Project (LIS2 is Phase 2)

Latitude: Latitude of grab sample station

Longitude: Longitude of grab sample station

PHI_13: percent of the sample mass that was falls into the grain size category Phi 13

PHI_12: percent of the sample mass that was falls into the grain size category Phi 12

PHI_11: percent of the sample mass that was falls into the grain size category Phi 11

PHI_10: percent of the sample mass that was falls into the grain size category Phi 10

PHI_9: percent of the sample mass that was falls into the grain size category Phi 9

PHI_8: percent of the sample mass that was falls into the grain size category Phi 8

PHI_7: percent of the sample mass that was falls into the grain size category Phi 7

PHI_6: percent of the sample mass that was falls into the grain size category Phi 6

PHI_5: percent of the sample mass that was falls into the grain size category Phi 5

PHI_4: percent of the sample mass that was falls into the grain size category Phi 4

PHI_3: percent of the sample mass that was falls into the grain size category Phi 3

PHI_2: percent of the sample mass that was falls into the grain size category Phi 2

PHI_1: percent of the sample mass that was falls into the grain size category Phi 1

PHI_0: percent of the sample mass that was falls into the grain size category Phi 0

PHIM1: percent of the sample mass that was falls into the grain size category Phi -1

PHIM2: percent of the sample mass that was falls into the grain size category Phi -2

PHIM3: percent of the sample mass that was falls into the grain size category Phi -3

PHIM4: percent of the sample mass that was falls into the grain size category Phi -4

PHIM5: percent of the sample mass that was falls into the grain size category Phi -5

gravel_pct: Percent of the sample mass that falls into the gravel category

sand_pct: Percent of the sample mass that falls into the sand category

silt_pct: Percent of the sample mass that falls into the silt category

clay_pct: Percent of the sample mass that falls into the clay category

mud_pct: Percent of the sample mass represents silt plus clay

median: calculated median grain size (in Phi)

mean: calculated mean grain size (in Phi)

stddev: Standard deviation of grain size around the mean (Phi)

skewness: calculated skewness of grain size distribution in sample

kurtosis: calculated kurtosis of gain size sample

gs_schlee: grain size classification following the Schlee classification schema

gs_falk: grain size classification following the Falk classification schema

CMECS_sub_orig: CMECS substrate origin

CMECS_sub_class: CMECS substrate class

CMECS_sub_subclass: CMECS substrate subclass

CMECS_sub_group: CMECS substrate group classification