Metadata: Identification_Information: Citation: Citation_Information: Originator: Robert P. Kucks Publication_Date: 1999 Title: Bouguer gravity anomaly data grid for the conterminous US Online_Linkage: https://mrdata.usgs.gov/services/gravity?request=getcapabilities&service=WMS&version=1.3.0& Larger_Work_Citation: Citation_Information: Originator: Phillips, Jeffrey D. Originator: Duval, Joseph S. Originator: Ambroziak, Russell A. Title: National geophysical data grids; gamma-ray, gravity, magnetic and topographic data for the conterminous United States Publication_Date: 1993 Series_Information: Series_Name: U.S. Geological Survey Digital Data Series Issue_Identification: DDS-9 Online_Linkage: http://pubs.er.usgs.gov/publication/ds9 Description: Abstract: The grid of gravity anomaly data for the conterminous United States and adjacent marine areas was constructed from National Information Mapping Agency (NIMA) gravity data files. It was reprojected to the specifications for the Spatial Data Delivery (SDD) project. Supplemental_Information: Digital Data Series DDS-9 (CD-ROM) contains gridded geophysical data (gravity anomaly data only defined here) images generated from the data, software for displaying and analyzing the images, software for processing potential-field geophysical data, and documentation files that describe the data and software. Purpose: Gravity anomalies are produced by density variations within the rocks of the Earth's crust and upper mantle. Mapping of these density variations is the primary use of gravity anomalies. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 1998 Ending_Date: 1999 Currentness_Reference: reprocessing for SDD website Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -125 East_Bounding_Coordinate: -65 North_Bounding_Coordinate: 49 South_Bounding_Coordinate: 25 Access_Constraints: None Use_Constraints: None Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Robert P. Kucks Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: Box 25046, MS 964 Denver Federal Center City: Denver State_or_Province: CO Postal_Code: 80225-0046 Country: USA Contact_Voice_Telephone: (303) 236-1405 Contact_Electronic_Mail_Address: rkucks@usgs.gov Data_Set_Credit: The compilation of onshore data consisted of nearly one million Bouguer gravity anomaly values computed by using a reduction density of 2.67 grams per cubic centimeter. The offshore data consisted of approximately 800,000 free-air gravity anomaly values. USGS employees: Godson and Scheibe Native_Data_Set_Environment: At the USGS, these data are stored in several binary gridded data formats on UNIX and PC systems. Data have been distributed in GEOSOFT GXF (an ASCII interchange format), Arc/Info export (e00), and ER Mapper binary format. Keywords: Theme: Theme_Keyword_Thesaurus: none Theme_Keyword: gravity, Bouguer Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Place: Place_Keyword_Thesaurus: none Place_Keyword: United States Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Gravity measurements made on the surface of the Earth must be corrected in various way before they can be made into an anomaly map. The free-air correction reduces the measurement to sea level by assuming there is no intervening mass as a uniform slab of constant density, and the complete Bouguer correction includes the effects of constant density topography within 166.7 km of the measurement location. A gravity reference field is subtracted from the corrected measurements to produce the free-air, simple Bouguer, or complete Bouguer anomaly. The data set constitutes many years of individual collection of gravity stations and therefore is difficult to access the precise accuracy. Quantitative_Attribute_Accuracy_Assessment: Attribute_Accuracy_Value: overall station accuracy of less than 2 milligals Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Earlier collection of stations was by surveying methods. Positions were also acquired from locations on topographic maps. Recently the station latitudes, longitudes and elevations were acquired by Geopositioning Satellite (GPS) systems. Quantitative_Horizontal_Positional_Accuracy_Assessment: Horizontal_Positional_Accuracy_Value: 100 Horizontal_Positional_Accuracy_Explanation: surveying methods - 1.0 meter topographic maps - 3.0 meter GPS systems - 100.0 meter/1.0 meter differential Vertical_Positional_Accuracy: Quantitative_Vertical_Positional_Accuracy_Assessment: Vertical_Positional_Accuracy_Value: 100 Vertical_Positional_Accuracy_Explanation: surveying methods - 1.0 meter topographic maps - 1.0-20.0 meter GPS systems - 100 meter/1.0 meter differential Lineage: Process_Step: Process_Description: gravity anomaly grid was extracted from DDS-9 and reprojected using USGS in-house developed software. In-house software was also used to convert from USGS grid format to Arc-Info grid format. Source_Used_Citation_Abbreviation: The "state-of-the-art" for gravity data collection changed significantly throughout the data collection period for this data set. Journals such as GEOPHYSICS have periodic articles describing the current state of standard procedures. Process_Date: 1999 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Robert P. Kucks Contact_Organization: U.S. Geological Survey Contact_Address: Address: Box 25046, MS 964 Denver Federal Center City: Denver State_or_Province: CO Postal_Code: 80225-0046 Country: USA Address_Type: mailing address Contact_Electronic_Mail_Address: rkucks@usgs.gov Contact_Voice_Telephone: (303)236-1405 Logical_Consistency_Report: The accuracy of the data set that generated the grid is totally dependant on the individual who collected each gravity station. In the case of a national set they would number in the hundreds. Variations would include latitude, longitude, elevation, raw gravity reading and base station control. Completeness_Report: There will always be upgrades and additions to the data set that generated the grid due to regional interests. Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Raster Raster_Object_Information: Raster_Object_Type: Grid cell Row_Count: 776 Column_Count: 1321 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Albers_Conical_Equal_Area: Standard_Parallel: 29.5 Standard_Parallel: 45.5 Longitude_of_Central_Meridian: -96.0 Latitude_of_Projection_Origin: 37.5 False_Easting: 0. False_Northing: 0. Map_Projection_Name: Albers Conical Equal Area Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: row and column Coordinate_Representation: Abscissa_Resolution: 4.0 Ordinate_Resolution: 4.0 Planar_Distance_Units: kilometer Geodetic_Model: Horizontal_Datum_Name: Noth American Datum of 1927 Ellipsoid_Name: CLARKE1866 Semi-major_Axis: 6378.20640 Denominator_of_Flattening_Ratio: 0.99661 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: grid cell Entity_Type_Definition: Area of Earth's surface for which gravity anomaly is summarized Attribute: Attribute_Label: cell value Attribute_Definition: Value, in milligals, of the gravity anomaly of Earth's gravitational field. Attribute_Definition_Source: Paterson, N.R., and Reeves, C.V., 1985, Applications of gravity and magnetic surveys: The state-of-the-art in 1985: Geophysics, v. 50, p. 2558-2594. Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -340 Range_Domain_Maximum: 95 Attribute_Units_of_Measure: milligal Attribute_Measurement_Resolution: 0.1 Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: -0.3402823E+39 Enumerated_Domain_Value_Definition: areas for which no data are available in the grid Distribution_Information: Distributor: Contact_Information: Contact_Person_Primary: Contact_Person: Robert P. Kucks Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: Box 25046, MS 964 Denver Federal Center City: Denver State_or_Province: CO Postal_Code: 80225 Country: USA Contact_Voice_Telephone: (303)236-1405 Contact_Electronic_Mail_Address: rkucks@usgs.gov Resource_Description: USGS Digital Data Series DDS-9 Distribution_Liability: The USGS has made every effort to verify the veracity of this information, but is not liable for any inaccuracies. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ArcInfo export Format_Version_Number: 7.x Format_Specification: Arc-Info grid format Format_Information_Content: Gridded gravity anomaly data File_Decompression_Technique: gunzip Transfer_Size: 3.5 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: ftp://ftpext.usgs.gov/pub/cr/co/denver/musette/pub/GEOPHYSICAL_DATA/cdrom_DDS-9/GRIDS/ARC_INFO/bouguer_sdd.e00.gz Digital_Form: Digital_Transfer_Information: Format_Name: GeoTIFF Format_Version_Number: 6 Format_Information_Content: Gridded gravity anomaly data Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://mrdata.usgs.gov/geophysics/gravity/USgrv_cba_SDD_geog.tif Digital_Form: Digital_Transfer_Information: Format_Name: OGC WMS Format_Version_Number: 1.3.0 Format_Information_Content: Bouguer gravity anomaly Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://mrdata.usgs.gov/services/gravity?request=getcapabilities&service=WMS&version=1.3.0& Fees: none Metadata_Reference_Information: Metadata_Date: 20180307 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Peter N Schweitzer Contact_Organization: USGS Eastern Mineral and Environmental Resources Science Center Contact_Position: Geologist Contact_Address: Address_Type: mailing address Address: 12201 Sunrise Valley Drive City: Reston State_or_Province: VA Postal_Code: 20192-0002 Country: USA Contact_Voice_Telephone: 703-648-6533 Contact_Facsimile_Telephone: 703-648-6252 Contact_Electronic_Mail_Address: pschweitzer@usgs.gov Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998