U.S. Geological Survey (USGS) color and pattern standards and conventions for geologic maps have evolved since the USGS published its first set of standards in 1881. Since that time, USGS personnel have continuously updated and revised the standards in response to the need to show increasingly complex geologic map data and in response to changing technology. The color and pattern standards and conventions contained in this book enable geologists, cartographers, and editors to produce geologic maps that have consistent geologic-age color schemes and patterns. Such consistency enables geologists and other users of geologic maps to obtain a wealth of geologic information at a glance and to produce maps that can easily be used and compared to other published maps that follow the color and pattern standards and conventions.