Version 2025-12-04: (_v1 files):

The lab data folder contains a .csv and a point shapefile that includes locations of samples analyzed for trace and major elements joined to analytical lab data.  Descriptions of analytical data fields are included in csv file.  Please note, shapefile truncates field names for analytical data.

Sample analytical method information can be obtained from the USGS publication: "Geochemical data generated by projects funded by the USGS Earth Mapping Resources Initiative (ver. 11.0, January 2025)"; doi:10.5066/P9WHRLXH.
Full citation: U.S. Geological Survey, 2021, Geochemical data generated by projects funded by the USGS Earth Mapping Resources Initiative (ver. 11.0, January 2025): U.S. Geological Survey data release, https://www.sciencebase.gov/catalog/item/601963c6d34edf5c66f0d0e5.

Each sample point has location fields, including Lat_WGS84 and Long_WGS84 (WGS 1984; WKID 4326), and depth of sample (in feet) if applicable. Abbreviations found in the below list of data fields can be found at the citation above.

This shapefile includes many (but not all) fields required for a points feature class in the Geologic Map Schema (GeMS) structure. The following field explanations may be useful:

Lab_No is a numerical field with a unique value for each sample. These numbers correspond to the USGS Geochemical data tables as well.
Field_No is a 7 character string that corresponds to GeochemistryPoints that may appear on 1:24,000 quadrangle geologic maps published by the Maryland Geological Survey in this area. H# connotes a hand-dug sample, D# connotes a drilled sample, G# connotes a grab sample.
Field_Name is a unique value for each sample, including the Field_No string plus a short description of the sample.
LocationCo is the field LocationConfidenceMeters in the GeMS structure.
PlotAtScal is the field PlotAtScale in the GeMS structure.
Depth_FT is measured from land surface elevation.

Samples that were analyzed under the C-WDXRF_BM (Base Metals) methodology were not analyzed for Chromium under this method. There are 8 samples that underwent supplemental Base Metals analysis.
