A subset of the National Geochemical Survey (NGS) samples covering the Indiana and Illinois State. Contains a total of 2681 point samples.
Data frame; contains the following columns:
factor; unique record identifier
factor; abbreviated dataset group e.g. "AK+MI"
factor; abbreviated description of sample type: stream, pond, spring, soil etc
integer; sampling date
numeric; longitude in decimal degrees (NAD27 datum)
numeric; latitude in decimal degrees (NAD27 datum)
factor; geodetic datum if different from NAD83
factor; relief in drainage basin from which sample was collected
factor; code or name of geologic formation in which sample area was located
factor; rock type in area of sample collection e.g. "carbonate"
factor; soil horizon from which the sample was collected
factor; observed color of powdered sample during splitting
factor; sample medium — rock, sediment, standard, or unknown
factor; geological source of the sample medium that was collected e.g. "Beach"
numeric; As (ppm) by Inductively Coupled Plasma Spectrometry (ICP) after acid dissolution
numeric; Cd (ppm)
numeric; Cr (ppm)
numeric; Cu (ppm)
numeric; Ni (ppm)
numeric; Zn (ppm)
numeric; As (ppm) by Hydride Atomic Absorption
numeric; Hg (ppm) by Hydride Atomic Absorption
numeric; Pb (ppm)
numeric; total carbon (weight percentage) by combustion
numeric; organic carbon (weight percentage) as a difference between
numeric; carbonate carbon (weight percentage) by Coulometric Titration
numeric; total sulfur (weight percentage) by combustion
Negative values of the heavy metal concetrations indicate a determination that is below the limit of detection for the analytic method used. The magnitude of the negative number indicates the detection limit. For example, -10 ppm means the result should be regarded as < 10 ppm.
National Geochemical Survey database is maintaned by the USGS National Geochemical Survey Team (contact: Peter Schweitzer). This subset has been prepared for the purpose of testing various geostatistical mapping algoriths by Tomislav Hengl ([email protected]).
The National Geochemical Survey Team, (2008) The National Geochemical Survey: database and documentation. U.S. Geological Survey Open-File Report 2004-1001, U.S. Geological Survey, Reston VA.
National Geochemical Survey database (http://mrdata.usgs.gov/geochem/)
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library(sp) # Load the NGS data: data(geochm) coordinates(geochm) <- ~LONGITUDE+LATITUDE proj4string(geochm) <- CRS("+proj=longlat +ellps=clrk66 +datum=NAD27 +no_defs") ## Not run: require(plotKML) data(SAGA_pal) # replace the missing values with half the detection limit: geochm$PB_ICP40 <- ifelse(geochm$PB_ICP40 < 0, 2, geochm$PB_ICP40) shape = "http://maps.google.com/mapfiles/kml/pal2/icon18.png" kml(geochm, shape = shape, colour = log1p(PB_ICP40), labels = "", colour_scale = SAGA_pal[], kmz = TRUE) ## End(Not run)
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