Surficial Geologic map of the Greater Omaha Area, Nebraska and Iowa

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What does this data set describe?

Title:
Surficial Geologic map of the Greater Omaha Area, Nebraska and Iowa
Abstract:
Geologic mapping, in support of the USGS Omaha-Kansas City Geologic Mapping Project, shows the spatial distribution of artificial-fill, alluvial, eolian, and glacial deposits and bedrock in and near Omaha, Nebraska. Artificial fill deposits are mapped chiefly beneath commercial structures, segments of interstate highways and other major highways, railroad tracks, airport runways, and military facilities, and in landfills and earth fills. Alluvial deposits are mapped beneath flood plains, in stream terraces, and on hill slopes. They include flood-plain and stream-channel alluvium, sheetwash alluvium, and undivided sheetwash alluvium and stream alluvium. Wind-deposited loess forms sheets that mantle inter-stream areas and late Wisconsin terrace alluvium. Peoria Loess is younger of the two loess sheets and covers much of the inter-stream area in the map area. Loveland Loess is older and is exposed in a few small areas in the eastern part of the map area. Glacial deposits are chiefly heterogeneous, ice-deposited, clayey material (till) and minor interstratified stream-deposited sand and gravel. Except for small outcrops, glacial deposits are covered by eolian and alluvial deposits throughout most of the map area. Bedrock is locally exposed in natural exposures along the major streams and in quarries. It consists of Dakota Sandstone and chiefly limestone and shale of the Lansing and Kansas City Groups. Sand and gravel in flood plain and stream-channel alluvium in the Platte River valley are used mainly for concrete aggregate. Limestone of the Lansing and Kansas City Groups is used for road-surfacing material, rip rap, and fill material.
Supplemental_Information:
Surficial deposits are mapped where they are estimated to be at least 1 m thick. Most of the surficial deposits are poorly exposed. The surficial deposits were locally observed in foundation excavations, road cuts, and other exposures in 1995 and 1996. Thin, discontinuous sheetwash alluvium (Qsw) and small artificial-fill deposits (af) were not mapped. Small outcrops of Loveland Loess, till, Dakota Sandstone, and limestone outcrops of the Lansing and Kansas City Groups that are too small to map are shown as symbols. Mapping in and near Omaha is modified from that of Miller (1964, plates 2 and 3 at 1:24,000 scale). Mapping in the rest of the map area is based primarily on interpretation of 1:15,840- and 1:20,000-scale county soil maps (Bartlett, 1975; Borchers and others, 1984; Branham, 1989; Nixon, 1982) and interpretation of aerial photography, supplemented by examination of artificial and natural exposures. The aerial photography includes: 1:40,000-scale, black-and-white, aerial photographs taken in April and May 1990 and in March and April 1993, and also 1:60,000-scale, color infrared, aerial photographs taken in May 1981 and April 1982. Age assignments for surficial deposits are based in part on soil development. Soil-horizon designations and textural terms, such as silt loam and clay loam, are those of the Soil Survey Staff (1975). Grain-size ranges given for surficial deposits are estimates that are based on the modified Wentworth scale (American Geological Institute, 1982). Dry matrix colors of the surficial deposits were determined by comparison with Munsell Soil Color Charts (Munsell Color, 1973). In general, colors of the surficial deposits are similar to those of the bedrock and other materials from which the deposits were derived. Unweathered to slightly weathered surficial deposits observed in the map area commonly range from gray (5Y 6/1) to very pale brown (10YR 8/4). In this report, the terms "alluvium" and "alluvial" refer to surficial material transported by running water confined to channels (stream alluvium) as well as material transported by running water not confined to channels (sheetwash alluvium). The term "colluvial" here refers to surficial material transported down slopes chiefly by mass-movement (gravity-driven) processes, such as creep. All of the radiocarbon and thermoluminescence ages in this report are uncalibrated. The thickness and grain-size ranges of surficial map units are based chiefly on interpretation of approximately 300 unpublished drill-hole logs and approximately 30 water-well logs on file with the Conservation and Survey Division, University of Nebraska-Lincoln, and test-hole data summarized by Burchett (1965) and Burchett and Smith (1989a, 1989b). Metric units are used in this report. (See text for complete bibliographic references.)
Coverages included in this geospatial database:
omgeo100 coverage: Contains all contact lines and labelpoints for each geologic polygon.
omter100 coverage: Contains geologic polygons for areas of Peoria Loess. These polygons are duplicates of ones found in omgeo100 for this unit and are used for cartographic purposes in overprinting pattern in these areas.
ompnt100 coverage: Contains geologic points for sites classified as bedrock, Loveland Loess, or Till.
ombdy100 coverage: Contains lines defining state and county boundaries derived from USGS DLG data.
omtrn100 coverage: Contains lines defining linear transportation features (highways and roads) derived from USGS DLG data.
omhyp100 coverage: Contains lines defining hypsographic features derived from USGS DLG data.
omhyd100 coverage: Contains polygons and lines defining hydrographic features derived from USGS DLG data.
ommea100 coverage: Contains lines defining scarps bordering former channels of the Missouri River.
  1. How might this data set be cited?
    Shroba, Ralph R., Brandt, Theodore R., and Blossom, Jeffrey C., 2001, Surficial Geologic map of the Greater Omaha Area, Nebraska and Iowa: U.S. Geological Survey Miscellaneous Field Studies Map MF-2391, United States Geological Survey, Denver, Colorado.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -96.25000
    East_Bounding_Coordinate: -95.87500
    North_Bounding_Coordinate: 41.37500
    South_Bounding_Coordinate: 41.00000
  3. What does it look like?
    http://pubs.usgs.gov/mf/2001/mf-2391/mf-2391.pdf (PDF)
    Printable digital version of the map layout, 8.7 megabytes.
    http://pubs.usgs.gov/mf/2001/mf-2391/mf-2391.gif (GIF)
    Reduced-size image of the entire map sheet, 288x223 pixels, 32-bit RGB true color, 23k bytes.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2000
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: map
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 14
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: -99
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000
      False_Northing: 0.0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 50
      Ordinates (y-coordinates) are specified to the nearest 50
      Planar coordinates are specified in Meters
      The horizontal datum used is North American Datum of 1927.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    Entity_and_Attribute_Overview:
    The data is supplied in ARC/INFO export format.
    This GIS database includes related look-up tables, which store detailed attribute information. Arc/Info relates for each coverage are saved in a file named <covername>.rel. Use the RELATE command with the restore argument at the arc prompt to make the relates active. Alternatively, in Arctools, use the Relate environment: open dialog in the Manage - Relates flyout menu under the Arctools menu to make the relates active.
    omgeo100 coverage: Contains all contact lines and labelpoints for each geologic polygon. In the omgeo100.pat INFO file the UNIT item indicates the numeric code used to identify the rock unit, which is described in the omgeo100.ru look-up table. The SOURCE item provides a numeric code used to identify the data source for the rock unit. Complete references for the sources listed are listed in the omgeo100.ref file. The LABEL item indicates the rock unit label (abbreviation) used to label unit on map. The DESC item defines formal or informal unit name. The SYMBOL item refers to the shade symbol in shadeset wpgcmykg.shd used to fill the geology polygons with color.
    In the coverage's omgeo100.aat INFO file the LINECODE item provides a numeric code used to identify type of linear feature. Linecodes < 100 are used for contacts and boundaries which are described in the omgeo100.con file. The NAME item lists the name given to structural feature. The SOURCE item lists the numeric code used to identify the data source for the linear feature. Complete references for the sources are listed in the omgeo100.ref file.
    Related look-up table files are omgeo100.con, omgeo100.ru, and omgeo100.ref. In the omgeo100.con INFO file, the LINECODE item indicates the numeric code (a value < 100) used to identify type of contact or boundary. This item relates directly to the LINECODE item in omgeo100.aat. The SYMBOL item lists the line symbol number used by Arc/Info to plot the line (Symbol numbers refer to the geol_sfo.lin lineset). The TYPE item lists the major type of line, e.g., contact, state boundaries, lines of latitude and longitude used for neatlines. The MODIFIER item lists the line type modifier, i.e., approximate, concealed, or gradational. No entry implies 'known'. The CERTAINTY item lists the degree of certainty of contact or boundary, i.e., inferred or uncertain. No entry implies 'certain'. The DESC item lists the written description or explanation of the contact or boundary. In the omgeo100.ru INFO file, the UNIT item refers to the numeric code used to identify the rock unit. The LABEL item refers to the rock unit label (abbreviation) used to label unit on map. The SYMBOL item indicates the shadeset symbol number used by Arc/Info to plot a filled/shaded polygon. (The symbol numbers used in this file refer to the wpgcmykg.shd shadeset.) The NAME item lists the prefix portion of the rock unit label that does not include subscripts. (If subscripting is not used in the original unit label, then the 'name' entry is the same as the 'label' entry.) The SS item lists the suffix portion of the rock unit label that includes subscripts. The LITH item list the major type of lithostratigraphic unit, i.e., unconsolidated sediments, sedimentary rocks, metasedimentary rocks, intrusive rocks, extrusive rocks, metamorphic rocks, water, and ice. The DESC item lists the formal or informal unit name. The MINAGE item indicates the minimum stratigraphic age of the lithologic unit, i.e. CRET, TERT, PCY. The MAXAGE item indicates the maximum stratigraphic age of the lithologic unit. The MINDATE item indicates the minimum radiometric age (in millions of years) if determined. The MAXDATE item indicates the maximum radiometric age (in millions of years) if determined. In the omgeo100.ref INFO file, the SOURCE item lists the numeric code used to identify the data source. The SCALE item lists the scale of the source map. (This value is the denominator of the proportional fraction that identifies the scale of the map that was digitized or scanned to produce the digital map.) The AUTHORS item lists the author(s) or compiler(s) of source map entered as last name, first name or initial, and middle initial. The YEAR item lists the source (map) publication date. The REFERENCE item lists the remainder of the reference in USGS reference format.
    The database structure used for this dataset follows the data model used in Lewis and Derkey (1999; USGS Open-File Report 99-438), and includes some attributes that, in this data set, do not have values, for structural consistency with the data model. For a more thorough description of this data model, please see http://pubs.usgs.gov/of/1999/0438/
    The INFO structure of these files is listed below: 
    OMGEO100.PAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  AREA                   8    18     F      5
    9  PERIMETER              8    18     F      5
   17  OMGEO100#              4     5     B      -
   21  OMGEO100-ID            4     5     B      -
   25  UNIT                   4     4     I      -
   29  SOURCE                 4     4     I      -
   33  LABEL                 10    10     C      -
   43  DESC                 100   100     C      -
  143  SYMBOL                 3     3     I      -


OMGEO100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 8    18     F      5
   25  OMGEO100#              4     5     B      -
   29  OMGEO100-ID            4     5     B      -
   33  LINECODE               3     3     I      -
   36  NAME                  30    30     C      -
   66  SOURCE                 4     4     I      -


OMGEO100.CON:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  LINECODE               3     3     I      -
    4  SYMBOL                 3     3     I      -
    7  TYPE                  10    10     C      -
   17  MODIFIER              20    20     C      -
   37  CERTAINTY             15    15     C      -
   52  DESC                 100   100     C      -


OMGEO100.RU:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  UNIT                   4     4     I      -
    5  LABEL                 10    10     C      -
   15  SYMBOL                 3     3     I      -
   18  NAME                   7     7     C      -
   25  SS                     3     3     C      -
   28  LITH                  20    20     C      -
   48  DESC                 250   250     C      -
  298  MINAGE                 7     7     C      -
  305  MAXAGE                 7     7     C      -
OMGEO100.REF:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    omter100 coverage: Contains geologic polygons for areas of Peoria Loess. These polygons are duplicates of ones found in omgeo100 for this unit and are used for cartographic purposes in overprinting pattern in these areas. The INFO structure of these files is listed below: 
    OMTER100.PAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  AREA                   8    18     F      5
    9  PERIMETER              8    18     F      5
   17  OMTER100#              4     5     B      -
   21  OMTER100-ID            4     5     B      -
   25  UNIT                   4     4     I      -
   29  SOURCE                 4     4     I      -
   33  LABEL                 10    10     C      -
   43  DESC                 100   100     C      -


OMTER100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 8    18     F      5
   25  OMTER100#              4     5     B      -
   29  OMTER100-ID            4     5     B      -
   33  LINECODE               3     3     I      -
   36  NAME                  30    30     C      -
   66  SOURCE                 4     4     I      -


OMTER100.CON:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  LINECODE               3     3     I      -
    4  SYMBOL                 3     3     I      -
    7  TYPE                  10    10     C      -
   17  MODIFIER              20    20     C      -
   37  CERTAINTY             15    15     C      -
   52  DESC                 100   100     C      -


OMTER100.REF:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    ompnt100 coverage: Contains geologic points for sites classified as bedrock, Loveland Loess, or Till. The INFO structure of these files is listed below: 
    OMPNT100.PAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  AREA                   8    18     F      5
    9  PERIMETER              8    18     F      5
   17  OMPNT100#              4     5     B      -
   21  OMPNT100-ID            4     5     B      -
   25  PTTYPE                32    32     C      -
   57  SYMBOL                 3     3     I      -
   60  SOURCE                 4     4     I      -


OMPNT100.REF:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    ombdy100 coverage: Contains lines defining state and county boundaries derived from USGS DLG data. The INFO structure of these files is listed below: 
    OMBDY100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 8    18     F      5
   25  OMBDY100#              4     5     B      -
   29  OMBDY100-ID            4     5     B      -
   33  LINECODE               3     3     I      -
   36  NAME                  30    30     C      -
   66  SOURCE                 4     4     I      -


OMBDY100.CON:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  LINECODE               3     3     I      -
    4  SYMBOL                 3     3     I      -
    7  TYPE                  10    10     C      -
   17  MODIFIER              20    20     C      -
   37  CERTAINTY             15    15     C      -
   52  DESC                 100   100     C      -


OMBDY100.REF:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    omtrn100 coverage: Contains lines defining linear transportation features (highways and roads) derived from USGS DLG data. The INFO structure of these files is listed below: 
    OMTRN100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 8    18     F      5
   25  OMTRN100#              4     5     B      -
   29  OMTRN100-ID            4     5     B      -
   33  ENTITY_LABEL           7     7     C      -
   40  ROUTE_NUMBER1          7     7     C      -


OMTRN100.REF:


COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    omhyp100 coverage: Contains lines defining hypsographic features derived from USGS DLG data. The ELEVATION_M item stores the 20 meter contour elevation data. The ENTITY_ LABEL item stores the DLG major/minor 0200200 code common to all arcs in the dataset, which identifies the type of hypsographic data. The INFO structure of these files is listed below: 
    OMHYP100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 8    18     F      5
   25  OMHYP100#              4     5     B      -
   29  OMHYP100-ID            4     5     B      -
   33  ENTITY_LABEL           7     7     C      -
   40  ELEVATION_M            8    12     F      3


OMHYP100.REF:


COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    omhyd100 coverage: Contains polygons and lines defining hydrographic features derived from USGS DLG data. The ENTITY_LABEL item defines major streams/rivers/lakes (polygons) as open water fill areas when coded 0500200. The INFO structure of these files is listed below: 
    OMHYD100.PAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  AREA                   8    18     F      5
    9  PERIMETER              8    18     F      5
   17  OMHYD100#              4     5     B      -
   21  OMHYD100-ID            4     5     B      -
   25  ENTITY_LABEL           7     7     C      -
   32  SOURCE                 4     4     I      -


OMHYD100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 8    18     F      5
   25  OMHYD100#              4     5     B      -
   29  OMHYD100-ID            4     5     B      -
   33  SOURCE                 4     4     I      -


OMHYD100.REF:


COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    ommea100 coverage: Contains lines defining scarps bordering former channels of the Missouri River. Hatchures point downslope. The INFO structure of these files is listed below: 
    OMMEA100.AAT:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  FNODE#                 4     5     B      -
    5  TNODE#                 4     5     B      -
    9  LPOLY#                 4     5     B      -
   13  RPOLY#                 4     5     B      -
   17  LENGTH                 4    12     F      3
   21  OMMEA100#              4     5     B      -
   25  OMMEA100-ID            4     5     B      -
   29  LINECODE               3     3     I      -
   32  NAME                  30    30     C      -
   62  SOURCE                 4     4     I      -


OMMEA100.STR:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  LINECODE               3     3     I      -
    4  SYMBOL                 3     3     I      -
    7  TYPE                  10    10     C      -
   17  HORIZONTAL            20    20     C      -
   37  VERTICAL              20    20     C      -
   57  FOLD                  15    15     C      -
   72  PLUNGE                15    15     C      -
   87  ACCURACY              15    15     C      -
  102  CERTAINTY             15    15     C      -
  117  DESC                 100   100     C      -


OMMEA100.REF:

COLUMN   ITEM NAME        WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
    1  SOURCE                 4     4     I      -
    5  SCALE                  8     8     I      -
   13  AUTHORS              200   200     C      -
  213  YEAR                   4     4     I      -
  217  REFERENCE            250   250     C      -
    Auxiliary files:
    geol_sfo.lin: This lineset file defines geologic line types in the geologically themed coverages.
    geoscamp2.mrk: This markerset file defines the geologic markers in the geologically themed coverages. To use this markerset, fnt037 must be in the user's directory.
    wpgcmykg.shd: This shadeset file defines the cmyk values of colors assigned to polygons in the geologically themed coverages.
    omgeo100.pdf: A file for viewing and printing a graphics version of the map and accessory elements using Adobe Acrobat viewing software (version 4.0).
    Coding of UNIT, LABEL, and DESC attributes in the omgeo100 coverage is listed below: 
    UNIT  | LABEL | DESC
1     | af    | Artificial fill deposits
2     | Qal   | Flood plain and stream channel alluvium
3     | Qsw   | Sheetwash alluvium
4     | Qss   | Sheetwash and stream alluvium
5     | Qlp   | Peoria Loess
6     | Qll   | Loveland Loess
7     | Qti   | Till
8     | R     | Bedrock
9     | w     | Open Water
    Coding of ENTITY_LABEL attribute numbers in the omtrn100 coverage is listed below: 
    Interstates
1700201
1700203
Minor highways
1700204
1700205
Main roads
1700209
Minor streets
1700210
1700211
Main road on/off ramps
1700402
    Entity_and_Attribute_Detail_Citation:

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Ralph R. Shroba
    • Theodore R. Brandt
    • Jeffrey C. Blossom
  2. Who also contributed to the data set?
    Shroba's knowledge of the surficial geology in the greater Omaha area was enhanced by informative discussions with Vincent Dreezen, Duane Eversoll, Joseph Mason, Vernon Souders, and Scott Summerside of the Nebraska Conservation and Survey Division. Earlier versions of this map were prepared with digital assistance provided from Maria Furey of the U.S. Geological Survey. This report was improved greatly by helpful reviews by Joseph Mason of the Nebraska Conservation and Survey Division and David Fullerton of the U.S. Geological Survey. Paco Van Sistine, Townsend Management Services, initially processed existing USGS Digital Line Graph data for transportation, hypsography, and hydrography themes used in this map.
  3. To whom should users address questions about the data?
    Ralph R. Shroba
    U.S. Geological Survey
    MS 913, Box 25046 DFC
    Denver, CO
    USA

    303-236-1292 (voice)
    303-236-0214 (FAX)
    rshroba@usgs.gov

Why was the data set created?

This map provides geologic information for land-use decisions.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 1999 (process 1 of 10)
    Polygons, lines, and points representing geologic features and data points were captured by scanning of 1:24,000 scale compilation linework, and vectorization using LT4X software. The resulting MOSS format files were imported into Arc/Info using the MOSSARC command. The resultant coverages were attributed with data describing the geologic units, contacts, structures and point locations.
    Date: 2000 (process 2 of 10)
    USGS 1:100,000 Digital Line Graph data for the transportation, hypsography, hydrography, and boundaries themes were imported into Arc/Info format and unnecessary items were eliminated using the DROPITEM command. Additional attribute items and data were added for the boundaries theme in order to describe and symbolize the lines.
    Date: 2000 (process 3 of 10)
    The Arc/Info GENERALIZE command was performed on the geology data theme using a weedtolerance of 22.0 and the BENDSIMPLIFY argument to detect and remove extraneous bends from the original lines.
    Date: 2000 (process 4 of 10)
    Arc/Info relates were created to link lookup table data containing symbol, description, and source data to all polygons, lines, and points.
    Date: 2000 (process 5 of 10)
    Differences among the geology, hydrography, and hypsography themes were resolved by the author and cartographer to improve the precision of the hydrography and hypsography themes based on the location of geologic contacts interpreted from aerial photography at a 1:24,000 compilation scale.
    Date: 2000 (process 6 of 10)
    Topological errors such as intersecterrors, labelerrors, sliver polygons, and duplicate arcs were identified and corrected.
    Date: 2000 (process 7 of 10)
    The database files, metadata, and check plots were edited by the USGS Central Publications Group, and revisions made to the geospatial database as needed.
    Date: 2000 (process 8 of 10)
    The geospatial database files and metadata were quality checked for completeness and consistency.
    Date: 2000 (process 9 of 10)
    Final preparation of the geospatial database for distribution, and preparation of map-on-demand files and metadata.
    Date: 11-Dec-2000 (process 10 of 10)
    Creation of original metadata record Person who carried out this activity:
    U.S. Geological Survey
    Attn: Ralph R. Shroba
    geologist
    U.S. Geological Survey
    Denver, CO
    USA

    303-236-1292 (voice)
    303-236-0214 (FAX)
    rshroba@usgs.gov
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Data were entered and checked by the geologist that made the field observations. The attributes of this geospatial data set consist of text identifiers and numeric codes that indicate the identity of the geologic unit or type of geologic feature, and determine how each feature is colored or symbolized. To check attribute accuracy, a color check plot was visually compared to the geologist's original compilation. Discrepancies between the digital geospatial dataset and the original analog compilation were corrected as needed. Machine-created listings of unique attribute values were used to identify spelling errors or other inconsistencies, and corrections were made as needed. This map has been thoroughly reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature.
  2. How accurate are the geographic locations?
    Lines were primarily positioned by photointerpretation of aerial photography and transferred to 1: 24, 000-scale topographic basemaps by visual inspection. Lines were scanned and vectorized from the basemap from scans with a resolution of 300 dots per inch. Most positions on the map are estimated to be accurate closer than 50 m horizontally.
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    Data are complete. No features that could be accurately represented at a scale of 1:100,000 were eliminated or generalized. The smallest area represented is approximately 95 square meters. All geospatial database elements are attributed.
  5. How consistent are the relationships among the observations, including topology?
    Map elements were visually checked for overshoots, undershoots, duplicate features, polygon closure, and other errors by the authors and by the GIS technician(s) who created the digital database. Automated (Arc/Info) routines were also used to check the databases for polygon label errors, line or point attribution errors, sliver polygons, dangling arcs, intersection errors, and projection information. Check plots of the map were reviewed by another geologist and cartographer for consistency with basic geologic principles and general conformity to USGS mapping standards.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints:
none. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Although software enables the user to display images at various scales, map data in this report should not be used at scales greater than 1:100,000.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Central Publications Group
    Lakewood, CO

    303-236-5486 (voice)
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Although this digital spatial data has been subjected to rigorous review and is substantially complete, it is released on the condition that neither the USGS nor the United States Government nor any agency thereof, nor any employees thereof, make any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. Any views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 14-Jun-2016
Metadata author:
Peter N Schweitzer
USGS Midwest Area
Collection manager, USGS Geoscience Data Clearinghouse, http://geo-nsdi.er.usgs.gov/
Mail Stop 954
12201 Sunrise Valley Dr
Reston, VA
USA

703-648-6533 (voice)
703-648-6252 (FAX)
pschweitzer@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://geo-nsdi.er.usgs.gov/metadata/map-mf/2391/metadata.faq.html>
Generated by mp version 2.9.48 on Tue Jul 03 20:05:15 2018