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.
"NCGMP09" Recommended Database Design
"NCGMP09" is the standard format for geologic maps funded by the USGS National Cooperative Geologic Mapping Program (NCGMP). It is designed for encoding content analagous to that contained in a single, traditional geologic map. NCGMP09 is intended to provide a stepping stone toward development of multimap databases, in particular the National Geologic Map Database (NGMDB).
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.
- Geologic Content Specification for a Single-Map Database [NGMDB,2010]
- Database Design for Map of Surficial Materials in the Conterminous United States [U.S. Geological Survey, 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.
Geologic Time Scales
Only the current USGS and International time scales are provided below. Because there are many other time scales, it's always advisable to cite in your publication the scale you're using.
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]
- Survey control points (e.g., benchmarks) [National Geodetic Survey, 2014]
- 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) [The National Atlas, 2013]
- Principal Meridians and Base Lines [Bureau of Land Management]
- Map Projections [Center for Spatially Integrated Social Science, 2014]
Tools and Techniques
A few handy coordinate-conversion utilities and other resources are provided below. Suggestions for additional links are welcome.
Publication Guidelines for Geologic Maps