Identification_Information: Citation: Citation_Information: Originator: Morin, Robert L. Originator: Glen, Jonathan M.G. Title: Principal facts for 463 gravity stations in the vicinity of Tangle Lakes, east-central Alaska Publication_Date: 2002 Series_Information: Series_Name: Open-File Report Issue_Identification: 02-96 Publication_Information: Publication_Place: Menlo Park, California Publisher: Geological Survey (U.S.) Online_Linkage: http://pubs.usgs.gov/of/2002/of02-096/ Description: Abstract: New gravity stations combined here with older measurements taken by other USGS survey trips Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 19580815 Ending_Date: 20010819 Currentness_Reference: Ground condition. Observations made during this time interval Status: Progress: Complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -147 East_Bounding_Coordinate: -145.5 North_Bounding_Coordinate: 63.5 South_Bounding_Coordinate: 62.5 Access_Constraints: none Use_Constraints: none Keywords: Place: Place_Keyword_Thesaurus: Augmented FIPS 10-4 and FIPS 6-4 Place_Keyword: f02170 = Matanuska-Susitna Place_Keyword: f02240 = Southeast Fairbanks Place_Keyword: f02261 = Valdez-Cordova Theme: Theme_Keyword_Thesaurus: General glossary for mineral resources spatial data Theme_Keyword: Portable Document Format Theme: Theme_Keyword_Thesaurus: USGS Thesaurus Theme_Keyword: geophysics Theme_Keyword: gravimeter measurement Theme_Keyword: gravitational field (earth) Point_of_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Robert L Morin Contact_Organization: USGS WR SW GD Contact_Address: Address_Type: mailing address Address: 345 Middlefield Road Mail Stop 989 City: Menlo Park State_or_Province: CA Postal_Code: 94025 Country: USA Contact_Voice_Telephone: 650-329-5320 Contact_Facsimile_Telephone: 650-329-5133 Contact_Electronic_Mail_Address: morin@usgs.gov Browse_Graphic: Browse_Graphic_File_Name: http://pubs.usgs.gov/of/2002/of02-096/images/OFR_02-96.png Browse_Graphic_File_Description: Index map showing locations of survey stations, with elevation contours, (561 x 639 pixels) Browse_Graphic_File_Type: PNG Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Point Point_and_Vector_Object_Information: SDTS_Terms_Description: SDTS_Point_and_Vector_Object_Type: Entity point Point_and_Vector_Object_Count: 463 Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Geographic: Geographic_Coordinate_Units: decimal degrees Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1927 Ellipsoid_Name: Clarke 1866 Semi-major_Axis: 6378206.4 Denominator_of_Flattening_Ratio: 294.98 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: table1.dbf Entity_Type_Definition: Principal facts of gravity stations Attribute: Attribute_Label: STA_NAME Attribute_Definition: Station identification number Attribute: Attribute_Label: LAT Attribute_Definition: Geographic latitude in degrees and decimal minutes Attribute: Attribute_Label: LATITUDE Attribute_Definition: Geographic latitude in decimal degrees Attribute: Attribute_Label: LONG Attribute_Definition: Geographic longitude in degrees and decimal minutes Attribute: Attribute_Label: LONGITUDE Attribute_Definition: Geographic longitude in decimal degrees Attribute: Attribute_Label: ELEV_FT Attribute_Definition: Elevation of the station in feet above mean sea level Attribute: Attribute_Label: OBS_GRAV Attribute_Definition: Observed gravity, mGal Attribute: Attribute_Label: ACC_CODE Attribute_Definition: Accuracy code consisting of four single-character codes: location source code, gravity source code, elevation source code, and simple Bouguer anomaly accuracy code Attribute: Attribute_Label: FAA_MGAL Attribute_Definition: Free air anomaly, in mGal Attribute: Attribute_Label: SBA_MGAL Attribute_Definition: Simple Bouguer anomaly, in mGal Attribute: Attribute_Label: CORR_INNER Attribute_Definition: Inner terrain correction in mGal Attribute: Attribute_Label: CORR_OUTER Attribute_Definition: Outer terrain correction in mGal Attribute: Attribute_Label: CBA_MGAL Attribute_Definition: Complete Bouguer anomaly in mGal Attribute: Attribute_Label: ISO_ANOM Attribute_Definition: Isostatic anomaly in mGal Attribute: Attribute_Label: DATA_CODE Attribute_Definition: Data set identifier code Attribute: Attribute_Label: 2ND_EL_AN Attribute_Definition: Secondary elevation, source code and simple Bouguer anomaly based on secondary elevation Attribute: Attribute_Label: ISO_CODE Attribute_Definition: Isostatic anomaly code Attribute: Attribute_Label: DATE Attribute_Definition: Year the measurement was made Overview_Description: Entity_and_Attribute_Overview: > Latitudes and longitudes are on the North American Datum of 1927 (NAD27). > Elevations are on the National Geodetic Vertical Datum of 1929 (NGVD29). > Theoretical gravity at sea level is based on the Geodetic Reference System 1967 (GRS67). > Observed gravity is on the IGSN71 datum. > Terrain corrections are calculated from 0.39 km to 166.7 km by computer program. > Inaccuracies in station elevations can generate large inner zone corrections > between the station and 0.39 km. > Values shown in the inner zone column are usually field corrections, which are field > estimates from the station to a radial distance of 53 m > The isostatic reduction assumes an Airy-Heiskanen model with the following parameters > from the station to 166.7 km: > density of topography above sea level, 2.67 g/cc > crustal thickness at sea level, 25 km > density contrast across the base of the model crust, 0.4 g/cc > From 166.7 km to a point on the opposite side of the Earth, isostatic and terrain > corrections were taken off maps by Karki. > > Location source code, column 47 > [NGS, National Geodetic Survey] > > Map used for field work transfer from > or for reading latitudes and longitudes good poor transfer smaller scale > or which controlled location position location location from photo field map > Modern published maps, scale 1:63,360 A B C D > Old or unpublished maps, scale 1:63,360 F G H I > Modern 1:250,000 scale maps K L M N > Reconnaissance 1:250,000 scale maps P Q R S > NGS or special maps U V W X > > Data from other agencies........Y > Location from special survey....Z > No location.....................? > Estimated or assumed location...# > Near a bench mark...............@ > Location from differential GPS..$ > Location from GPS...............% > > Gravity source code, column 48 > > 3 ties other ties or drift loops lasting > within multiple > Type of meter 0.1 mGal ties <6 hours 6-24 hours 1-4 days >4 days > LaCoste & Romberg Geodetic meters A B C D E F > Worden or (loop drift control) G H I J K L > World-Wide (other drift control) M N O P Q R > meters (no drift control) S T U > Old LaCoste & Romberg or other > thermostated meters V W X > > Data from other agencies...Y > Reasons to expect errors...Z > > > Elevation source code, column 49 > [USWB, U.S. Weather Bureau; FAA, Federal Aviation Administration; > Wisc, University of Wisconsin] > > highway & USWB > railway special FAA > bench marks surveys sea Level surveys Wisc > Surveys, etc. A B C D E > black brown blue unpublished maps > Map elevations F G H I > > Contour interval > 0-50 ft 100 ft 200 ft > River gradient interpolation J K L > Good contour interpolation M N O > Poor contour interpolation P P Q > > Altimetry Base Distance > <15 miles 15-70 miles >70 miles > Good repeated readings R S - > Alticorder or other good base control T U - > Poor control V W X > > Altimetry involving special adjustments.........Y > No data.........................................? > Elevation from nearby bench marks...............@ Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/of/2002/of02-096/ Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: USGS Information Services Contact_Address: Address_Type: mailing Address: Box 25286, Denver Federal Center City: Denver State_or_Province: Colorado Postal_Code: 80255-0046 Country: USA Contact_Voice_Telephone: 1-888-ASK-USGS Contact_Facsimile_Telephone: 1-303-202-4695 Contact_Electronic_Mail_Address: infoservices@usgs.gov Resource_Description: USGS Open-File Report 02-96 Distribution_Liability: This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards (or with the North American Stratigraphic Code). Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: Shapefile Format_Version_Number: 1.0 Format_Information_Content: Gravity station data File_Decompression_Technique: unzip Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://pubs.usgs.gov/of/2002/of02-096/ Fees: none Metadata_Reference_Information: Metadata_Date: 20081006 Metadata_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Peter N Schweitzer Contact_Organization: USGS ER GD 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