Guam Geologic Map Units

Metadata:

• Entity_and_Attribute_Information
• Identification_Information
• Data_Quality_Information
• Metadata_Reference_Information
• Spatial_Reference_Information
• Spatial_Data_Organization_Information
• Lineage

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: geology_detailed

Attribute:

Attribute_Label: OBJECTID

Attribute_Definition: Internal feature number.

Attribute_Definition_Source: Esri

Attribute_Domain_Values:

Unrepresentable_Domain:

Sequential unique whole numbers that are automatically generated.

Attribute:

Attribute_Label: Shape

Attribute_Definition: Feature geometry.

Attribute_Definition_Source: Esri

Attribute_Domain_Values:

Unrepresentable_Domain: Coordinates defining the features.

Attribute:

Attribute_Label: Code

Attribute:

Attribute_Label: MapUnit

Attribute:

Attribute_Label: Formation

Attribute:

Attribute_Label: Epoch

Attribute:

Attribute_Label: Area_acres

Attribute:

Attribute_Label: Area_ha

Attribute:

Attribute_Label: Area_m2

Attribute:

Attribute_Label: Perimtr_m

Attribute:

Attribute_Label: Perimtr_mi

Attribute:

Attribute_Label: Shape_Length

Attribute_Definition: Length of feature in internal units.

Attribute_Definition_Source: Esri

Attribute_Domain_Values:

Unrepresentable_Domain: Positive real numbers that are automatically generated.

Attribute:

Attribute_Label: Shape_Area

Attribute_Definition: Area of feature in internal units squared.

Attribute_Definition_Source: Esri

Attribute_Domain_Values:

Unrepresentable_Domain: Positive real numbers that are automatically generated.

Identification_Information:

Description:

Abstract:

This dataset contains the geologic map units of the island of Guam.

Purpose:

This dataset was developed to provide up-to-date GIS coverage of geologic information that reflects the recent update of the Geologic Map of Guam (2008) by Siegrist and Reagan. The map was originally published in 2008 as a 1:50,000-scale hard-copy map and in digital format as PDFs consisting of nine 1:24,000-scale and one 1:50,000-scale. Reference: Siegrist, H.G. and Reagan, M.K.. Geologic Map and Sections of Guam, Mariana Islands (1:50,000), Revisions of original map from USGS Professional Report 403A, 1964, by Tracey, J.I., Jr., Schlanger, S.O., Stark, J.T., Doan, D.B. & May, H.G.

Data_Set_Credit:

Siegrist, H.G., and Reagan, M.K. 2008. Geologic Map and Sections of Guam, Mariana Islands (1:50,000), Revisions of original map from USGS Professional Report 403A, 1964, by Tracey, J.I., Jr., Schlanger, S.O., Stark, J.T., Doan, D.B. & May, H.G.
Additional contributions to the map in form of field interpretations were made by Richard H. Randall and John W. Jenson. Digital cartography in Adobe Illustrator by Linda Masonic (USGS). Geographic Information System (GIS) database by Maria Kottermair, University of Guam (WERI).

Point_of_Contact:

Contact_Information:

Contact_Position: Professor of Environmental Geology

Contact_Address:

Address_Type: mailing and physical address

Address: University Drive

City: Mangilao

State_or_Province: Guam

Postal_Code: 92923

Country: U.S.A.

Contact_Electronic_Mail_Address: jjenson@uguam.uog.edu

Contact_Voice_Telephone: 671-735-2689

Contact_Organization_Primary:

Contact_Organization:

Water & Environmental Research Institute (WERI), University of Guam

Contact_Person: Dr. John Jenson

Citation:

Citation_Information:

Originator: Water & Environmental Research Institute, University of Guam

Publication_Date: 2012

Title: Guam Geologic Map Units

Online_Linkage: www.hydroguam.net

Geospatial_Data_Presentation_Form: vector digital data

Keywords:

Theme:

Theme_Keyword: Geologic Map of Guam

Theme_Keyword: geologic features

Theme_Keyword: map units

Theme_Keyword: geology

Place:

Place_Keyword: Guam

Place_Keyword: Mariana Islands

Place_Keyword: Pacific Islands

Place_Keyword: Western Pacific

Place_Keyword: Northwestern Pacific

Place_Keyword: United States Possesion

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 2008

Currentness_Reference: publication date

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Use_Constraints:

Dataset is for planning purpose only, not for use in litigation. The Water & Environmental Research Institute (WERI) cannot assume liability for any damages or misrepresentations caused by any inaccuracies in the data or as a result of the data to be in a particular system.

Data_Quality_Information:

Logical_Consistency_Report:

The logical consistency of the geometry of this dataset was checked using the ET GeoWizard tool "Clean Polygon Layer" and "Clean gaps".

Lineage:

Source_Information:

Source_Citation:

Citation_Information:

Originator: H.G. Siegrist, Jr and Mark K. Reagan

Publication_Date: 2008

Title: Geologic Map of Guam

Other_Citation_Details:

Siegrist, H.G., and Reagan, M.K. 2008. Geologic Map and Sections of Guam, Mariana Islands (1:50,000), Revisions of original map from USGS Professional Report 403A, 1964, by Tracey, J.I., Jr., Schlanger, S.O., Stark, J.T., Doan, D.B. & May, H.G.

Online_Linkage:

<http://www.weriguam.org/locally-sponsored-research/guam-hydrologic-survey/page/geologic-maps.html>

Type_of_Source_Media: PDF files

Source_Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 2008

Source_Currentness_Reference: publication date

Source_Contribution: Primary source for on-screen digitizing.

Process_Step:

Process_Description:

All nine (9) Geologic Map of Guam quadrangle maps (1:24,000) in PDF-format were exported to TIFF in Adobe Photoshop. Each map was then imported to ArcMap and georeferenced using the four corners of each map for ground control points (GCPs). The Total RSME Error for each quadrangle map was between 0.27 and 0.65 meter. A first order polynomial (affine) transformation was used to rectify the images. The 1:50,000 map covering all of Guam was also rectified using over 50 GCPs. However, it was only used as reference and not as source data since it did not overlay the USGS topographic maps (DRGs) and the WorldView2 satellite imagery as well as the quadrangle maps.

Process_Date: 2011

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Maria Kottermair

Contact_Organization: Water & Environmental Research Institute, University of Guam

Contact_Position: Research Assistant III (GIS Analyst)

Contact_Voice_Telephone: 671-735-2685

Contact_Electronic_Mail_Address: mariakottermair@uguamlive.uog.edu

Process_Step:

Process_Description:

The rectified images were then used to trace the outlines of the geologic features using ArcScan. Attributes as seen on the maps were added. The outlines were extended beyond the shoreline and later clipped using the 2006 shoreline polygon.

Process_Date: 2011/2012

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Maria Kottermair

Process_Step:

Process_Description:

Topology of the polygons was checked using the ET GeoWizard tool "Clean Polygon Layer" and "Clean gaps".

Process_Date: 2012

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Maria Kottermair

Source_Produced_Citation_Abbreviation: Guam_Geology_Update_2008

Attribute_Accuracy:

Attribute_Accuracy_Report:

This dataset is considered complete and accurate based on the source maps. Presently, there are no plans to conduct an accuracy assessment. Updates may be provided at a later date as more ground-truthing information becomes available.

Completeness_Report: This dataset is considered complete.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

The polygons were created by tracing the nine (9) georeferenced Geologic Map of Guam quadrangle maps (1:24,000). The quadrangle topo maps follow the National Map Accuracy Standard. The geologic map is likely to follow that standard although no documentation was found to support that. Additional errors may have been introduced by geo-referencing and/ or digitizing. However, both types of errors are believed to be minor as geo-referencing was done by using the coordinates of the four corners of each map as ground control points; the georefernced maps overlaid well the USGS topo maps (< 10 meter discrepancy) and WorldView2 satellite imagery. Also, the outlines of the polygons were traced using ArcScan and should therefore be identical to the scanned georeferenced map. No positional accuracy assessment has been performed in the field.

Metadata_Reference_Information:

Metadata_Date: 20120921

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Maria Kottermair

Contact_Organization: Water & Environmental Research Institute, University of Guam

Contact_Position: Research Assistant III (GIS Analyst)

Contact_Voice_Telephone: 671735-2685

Contact_Electronic_Mail_Address: mariakottermair@uguamlive.uog.edu

Metadata_Review_Date: 20131010

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geodetic_Model:

Horizontal_Datum_Name: D_WGS_1984

Ellipsoid_Name: WGS_1984

Planar:

Planar_Coordinate_Information:

Planar_Distance_Units: meters

Spatial_Data_Organization_Information:

Point_and_Vector_Object_Information:

Lineage: