To create, manage, and disseminate digital earth-science information, it is increasingly clear to data producers and users that certain widely-accepted standards are essential. In the past, many organizational units (e.g., projects or programs) have of necessity developed their own standard practices for creating and managing digital map data. Because the resources needed to develop widely-accepted standards are difficult for a single organizational unit to justify, many of these standard practices developed in an ad hoc fashion, with scant input from other groups.
Two notable mechanisms now exist in the United States to promote the coordination of widely-accepted standards: 1) the National Geologic Mapping Act of 1992 stipulates that necessary standards be developed by USGS and the Association of American State Geologists (AASG) to support the National Geologic Map Database (NGMDB); and 2) the Federal Geographic Data Committee (FGDC), through its Geologic Data Subcommittee, is responsible for development of standards to support geologic data management at the Federal level.
The links below contain information pertinent to the development of standards and guidelines for geologic mapping. Many of these works stemmed from discussions held at the annual Digital Mapping Techniques workshop, sponsored by the NGMDB and the Association of American State Geologists. The beginning stages of this work (ca. 1996-1997) are documented and preserved in an archival site and in the earliest NGMDB reports of progress.
"GeMS" — standard Geologic Map Schema
"GeMS" (formerly named NCGMP09) is the standard schema for geologic maps funded by the USGS National Cooperative Geologic Mapping Program (NCGMP). Its design specifies encoding the content analagous to that contained in a single, traditional geologic map. GeMS is intended to provide a stepping stone toward development of multimap databases, in particular the National Geologic Map Database (NGMDB). Please visit our GeMS site.
Related, Older Database Designs
This list focuses on the work by USGS and AASG staff, ca. 1998-2010, to define conceptual data models and physical implementations, mostly preceding development of NCGMP09.
- North American Data Model - v. 1.0 [USGS, Geological Survey of Canada, 2004]
- NADM Design, esp. see Variants and Implementations [North American Data Model Steering Committee, 2004]
- NGMDB-Lite -- Database design for the National Geologic Map Database's Data Portal [NGMDB,2010]
Additional Resources
- Geologic Content Specification for a Single-Map Database [NGMDB,2010]
- Database Design for Map of Surficial Materials in the Conterminous United States [USGS, 2010]
- NGMDB Geologic Map Feature Class Model [NGMDB, 2005]
- Implementing NADM C1 for the National Geologic Map Database [NGMDB, 2004]
- Developing the North American Geologic Map Data Model [North American Data Model Steering Committee, 2001]
- Progress Report on the National Geologic Map Database, Phase 3: An Online Database of Map Information [NGMDB, 2001]
- The Central Kentucky Prototype: An Object-Oriented Geologic Map Data Model for the National Geologic Map Database [NGMDB, 2001]
- Prototype Implementation of the NADMSC Draft Standard Data Model, Greater Yellowstone Area [NGMDB, 2000]
- Developing the National Geologic Map Database, Phase 3 -- An Online, "Living" Database of Map Information [NGMDB, 2000]
- Digital Geologic Map Data Model, Version 4.3 [USGS/AASG Geologic Map Data Model Working Group, 1999]
- Progress Toward Development of a Standard Geologic Map Data Model [USGS/AASG Geologic Map Data Model Working Group, 1998]
FGDC Cartography Standards
The National Standard for the digital cartographic representation of geologic map features.
- FGDC Digital Cartographic Standard for Geologic Map Symbolization — Publication website. [Federal Geographic Data Committee, 2006]
- ArcGIS Pro style implementation of FGDC Standard — Comprehensive and authoritative implementation of the standard created by the South Carolina Geological Survey for the NGMDB. Requires installation of the font files below. See Additional Resources for style files that work in ArcMap
- FGDCGeoAge.otf — OpenType version of special geologic age characters
- FGDCGeoSym — five TrueType font files
of geologic marker symbols used for decorating line symbols and symbolizing points.
Additional Resources
- AK GeMS symbology — Nearly complete ArcMap style implementation of FGDC standard with additional custom symbols. [Alaska Division of Geological and Geophysical Surveys, 2021]
- FGDCcmyk — ArcMap and ArcGIS Pro style files containing only the polygon fill colors shown in the FGDC CMYK Color Chart. Also known as wpgcmyk.style and derived from the ArcINFO shadeset wpgcmyk.shd.
- Selection of colors and patterns for geologic maps of the U.S. Geological Survey [USGS, 2005]
- Field Description of the Scientific and Locational Accuracy of Geologic Features (a Part of the Draft FGDC Geologic Map Symbolization Standard) [USGS, 2002]
- Development and Public Review of the Draft "Digital Cartographic Standard for Geologic Map Symbolization" [USGS, 2000]
- esriNcgmp Online Geologic Mapping Template (ESRI v.10 SP1) [ESRI, 2012]
- GSC ArcMap style partial implementation of FGDC Standard [Geological Survey of Canada, 2010]
- Integrating Style Files and Carto Representation into the Geological Map Flow Process (The GSC's implementation of the FGDC geologic symbology) [Geological Survey of Canada, 2010]
- Shell's Standard Legend of cartographic symbols for the petroleum industry [Shell Oil, 2017]
Metadata
The NGMDB requires that metadata for submitted geologic geospatial data are in the FGDC Content Standard for Digital Spatial Metadata (CSDGM)
- FGDC-CSDGM representations and tools [FGDC]
- Formal metadata: information and software [USGS]
- Geospatial Metadata Validation Service [USGS]
- Metadata Creation — In particular, a good listing of tools [USGS]
Geologic Time Scales
At the Geolex site, we provide some information and links to selected time scales. It's always advisable to cite in your publication the time scale you're using.
Science Terminologies
Many classifications have been devised in attempts to organize and standardize descriptions of geologic map units, both to improve science and to more clearly convey geologic information to the public. Of necessity, such classifications are compromises that only partially describe the near-infinity of map-unit compositions, textures, genesis, and appearance. In this section, selected terminologies developed by USGS and AASG in support of joint efforts to devise a common database design are highlighted. The reader also is encouraged to consult the vast body of published literature on this subject.
- NCGMP09 GeneralLithology [U.S. National Cooperative Geologic Mapping Program, 2010]
- Rationale for GeneralLithology, in "A Classification of Geologic Materials for Web Display of National and Regional-Scale Mapping" [NGMDB, 2009]
- Report on Progress to Develop a North American Science-Language Standard for Digital Geologic-Map Databases [North American Data Model Steering Committee, 2004]
- Appendix A. Philosophical and operational guidelines for developing a North American science-language standard for digital geologic-map databases [North American Data Model Steering Committee, 2004]
- Appendix B. Classification of metamorphic and other composite-genesis rocks, including hydrothermally altered, impact-metamorphic, mylonitic, and cataclastic rocks [North American Data Model Steering Committee, 2004]
- Appendix C. Sedimentary materials: Science language for their classification, description, and interpretation in digital geologic-map databases [North American Data Model Steering Committee, 2004]
- Appendix D. Volcanic materials: Science language for their naming and characterization in digital geologic-map databases [North American Data Model Steering Committee, 2004]
- NADM Web site [North American Data Model Steering Committee, 2004]
- Geoscience Terminology Development for the National Geologic Map Database [NGMDB, 2003]
- CGI vocabularies [CGI Geoscience Terminology Working Group, 2014]
Base Maps and Projections
Topographic and cultural information are essential to a well-constructed geologic map. This section provides some links on major topics, including map projections.
- Topoview -- Browse the Nation's topo maps [USGS]
- The National Map -- topo, 3DEP, ... [USGS]
- Geographic Names Database [U.S. Board on Geographic Names, 2014]
- Finding survey marks (e.g., benchmarks) [National Geodetic Survey]
- National Geodetic Survey Data Explorer [National Geodetic Survey, 2014]
- Federal Lands Records [Bureau of Land Management,2014]
- An album of map projections [USGS PP 1453, 1989]
- Bibliography of map projections [USGS Bull. 1856, 1988]
- Map Projections: A Working Manual [USGS PP 1395, 1987]
- The Public Land Survey System (PLSS)
- Principal Meridians and Base Lines
Tools and Techniques
A few handy coordinate-conversion utilities and other resources are provided below. Suggestions for additional links are welcome.
- Get bounding coords in various output formats ["Extent Helper", NGMDB]
- Coordinate conversion utilities [Earth Point]
- State Plane - Lat/Long converter [National Geodetic Survey]
- Geodetic tool kit [National Geodetic Survey]
- Pick sets of colors (by hex, HSV, RGB) [colorpicker.com]
- Pick sets of colors (by hex) [hailpixel.com]
- Pick a color scheme [colorbrewer2.org]
- Comparison of digital geologic field systems [Wikipedia]
- Various reports in the Digital Mapping Techniques Proceedings [USGS, 1997-present]
Publication Guidelines for Geologic Maps
- Suggestions to Authors of the Reports of the United States Geological Survey [USGS, 1991]
- Guidelines for Digital Review of a Geological Map Database [U.S. National Cooperative Geologic Mapping Program, 2010]
- Guidelines for Peer Review of a Geologic Map Product [U.S. National Cooperative Geologic Mapping Program, 2010]
- Recommended Citations for Unpublished GIS Files — Summary of a Discussion Session [Digital Mapping Techniques Proceedings, 2010]
- Map Authorship and Citation Guidelines: Summary of a Discussion Session [Digital Mapping Techniques Proceedings, 2001]