Methods to create ArcMap styles with examples for lithology and time

Abstract

ArcMap style files (.style extension) can be used to standardize map symbolization. This report describes the methods used to create several styles for lithology or geologic time. The styles are color fills which were created by assigning RGB color values to attributes of polygon shapefiles. The terms symbolized were either generated from terminology hierarchies from various sources or digitized from scanned images of existing legends. For large lithology lists, a table format was used as a convenient method for experimenting with shades of color as well as for documenting the RGB color values. Examples of styles were adapted or created from the following legends: the International Stratigraphic Chart (ISC) and the USGS Color Code version of the ISC; the Decade of North American Geology (DNAG-1983 Geologic Time Scale); the North American Geologic Map Data Model version 4.3 (specifically lithclass 4.3 and its successors lithclass 6.1 and lithclass 6.2); and the State Geologic Map Compilation (SGMC). The digital package consists of ArcMap styles, and Microsoft Excel color documentation tables. The software used includes Environmental Systems Research Institute (ESRI) ArcGIS version 9 (ArcMap module) and Microsoft Excel 2003. Other software tools used in preparing the files were Pixie color-picker, and the Science Language Interface Module. Introduction It is desirable to have standardized styles available for lithology and geologic time for mineral resource and other geologic uses, especially for suites of maps. Selecting color fills for large lithologies consisting of hundreds of units while maintaining a visual distinction in the traditionally accepted color ranges is a time-consuming process. The ESRI ArcMap style files (.style extension) released with this report offer examples of ready-made color fills that can improve map communication by presenting a uniform appearance. Fills are identified by textual names which appear as attributes of the polygons being symbolized. The report describes a spreadsheet method that was used for selecting color fills as well as for documentation of RGB (red, green, blue) color codes. The digital files are available online at http://pubs.usgs.gov/of/2005/1314/. Background information on existing lithology color schemes can be found in Compton (1962), the American Association of Petroleum Geologists Correlation Chart Series (1983), and the Pacific Northwest lithology map by Johnson and Raines (2001). Examples of terminology schemes can be found in Compton (1962), Streckeisen (1973a, 1973b), Folk (1974), Pettijohn (1975), Gilliespie and Styles (1999), Roberson (1999), and Hallsworth and Knox (1999).