GEOSPATIAL RESOURCES FOR THE GEOLOGIC COMMUNITY: THE USGS NATIONAL MAP

Geospatial data are a key component of investigating, interpreting, and communicating the geological sciences. Locating these data can be time consuming which detracts from time spent on a study because these data are not obviously placed in central locations or they are served from many disparate databases. The U.S. Geological Survey’s National Map is a publicly available resource for accessing geospatial base map data needs of the geological community from a central location. National Map data is available through a geospatial viewer and download platform providing access to eight primary data themes plus the US Topo and scanned historical topographic maps. The eight themes include Elevation, Orthoimagery, Hydrography, Geographic Names, Boundaries, Transportation, Structures and Land Cover and are progressively being offered for download as pre-defined tiles in formats supported by leading GIS software. Data tiles are periodically refreshed to capture the most current content and are an efficient method for disseminating and receiving geospatial information. Elevation data, for example, is offered as a download from the National Elevation Dataset as 1 x 1 degree cells for the 10 and 30 meter product and as 15 x 15 minute cells for the higher resolution 3 meter product. Vector datasets with smaller file sizes are offered at several tile sizes that are registered to the zoom scale of the requesting bounding area in the viewer. Partial tiles are not a download option—any pre-staged data that intersects the requesting bounding box will be, in entirety, part of the data download order. While there are many options for accessing geospatial data via the web, The National Map represents authoritative sources of data that receive extensive quality assurance. Therefore, The National Map products and services should be part of a geologist’s first stop for geospatial information and data.