1.) GIS features were produced from source digital data. See the Source Information Contribution section(s) for specific source map details. GIS features were imported into a geodatabase as per the GRI data model. Topology rules were then imposed and validated, as per the GRI data model, to check for and correct topology errors. Quality control (QC) consisting of a visual check and/or queries of the data against its source (where applicable), as well as running a GRI developed script (QC_Script) to check for GRI data model validation and feature-related consistency, was conducted. 2.) GIS table attribution was derived and checked using the source digital data file(s). Relationship classes were also used to ensure attribution consistency between feature class and table attribution. For details on the GRI data model see the NPS GRI Geology-GIS Geodatabase Data Model v. 2.1 (available at: http://science.nature.nps.gov/im/inventory/geology/GeologyGISDataModel.cfm). 3.) GIS feature classes were then exported from the geodatabase to shapefile (.SHP) format, and GIS tables exported from the geodatabase to DBASEIV (.DBF) format. 4.) The map-related pdf document, see the Supplemental Information section for additional information, was produced from textual information and figures present on the source map(s) and/or in digital data files. If applicable, source map images were produced at 150dpi or greater resolution and optical character recognition (OCR) software was used to produce text from source map text. The text, source map images and other ancillary source map information were added to a Help & Manual (.HMX) template file. The Help & Manual (.HMX) file was then compiled to produce the .PDF map document. Any compilation errors were then checked and corrected and the document was reviewed for content, usability and grammatical errors.