The National Geologic Map Database Map Viewer
As we describe in the book The GIS Guide to Public Domain Data, the AASG-USGS National Geologic Map Database (NGMDB), is one of the most useful resources to access geologic maps and data. The NGMDB, through its Geoscience Map Catalog, provides access to more than 89,000 maps and reports by more 630 publishers. More than 23,000 of these publications are geologic maps. A significant leap forward since the book was published is the new NGMDB Map Viewer. This Mapviewer is built using Esri ArcGIS Server and the Image Server Extension. With the viewer, inside ArcGIS Online inside an ordinary web browser, data users can access a significant component of the national archive of the systematic, regional mapping of bedrock and surficial deposits, conducted by Federal, State, University, and private entities, stretching back to the 1800s.
Why access the NGMDB through this map viewer? There are several advantages to doing so: You can view numerous maps in the NGMDB Map Catalog in one seamless interface running in your web browser. You can toggle between selected map types, search by keyword to find a record in the Map Catalog, find related publications, and best of all, access the Map Catalog to download high resolution geotiffs and other GIS-compatible formats. I formerly worked at the USGS, and have been in touch with colleagues there over the past year, eagerly awaiting the arrival of this map viewer. If you have read our book or have been reading this blog, you know that Jill Clark and I cast a rather critical eye on any data portal or viewer, assessing whether any of them are truly useful for the GIS data user. I am pleased to report that after testing the NGMDB Map Viewer, it met all of my expectations. True, the database is largely (but not entirely) US-based, but the interface is easy to use and allows the data users to obtain what they came for–GIS-compatible geologic data of different areas, scales, and themes.