Geologic heritage sites tend to have extraordinary visual appeal and represent a resource of great economic significance, which explains why Native Americans and early explorers, miners and pioneers were drawn to them. Over time, as Congress added to the National Park System, the variety and diversity of geologic features in parks has come to represent America's geologic heritage. The National Park System, spanning features from erupting volcanoes to tidewater glaciers and dynamic barrier islands to fossilized dinosaurs, might rightfully be called the world's greatest rock collection. Park visitors and the public assume that the landscapes and iconic geologic features in parks are well cared for. However, in many park units, geologic features are less recognized and understood than non-park National Natural Landmarks.
National Park Service units are set aside and granted protections pursuant to either Presidential proclamations or Congressional enabling acts. Title 16 of the United States Code contains the most current, as amended enabling legislation for the vast majority of park units. In many cases the primary reasons for why a park was set aside in the first place are not clear from the most current codified version of a park's enabling legislation. Thus, it is important to go back further and trace the legislative history back to the dates of establishment. A thorough review of legislative record reveals 68 park units where geologic significance is explicitly noted their Presidential proclamations or Congressional enabling acts. An additional 21 parks have a record of being set aside primarily for geologic significance, although not specifically mentioned in their legislation.
More than 180 parks have significant geologic resources, 170 contain noteworthy fossils, 97 have dynamic shoreline geology, 60 have cave and karst systems, 49 have volcanic features, and 24 have geothermal features. In 1998, a law was passed that mandated the Park Service to use "science based decision-making" to guide its management activities. The National Park Service, through the Geologic Resources Division, is beginning to inventory all of its significant geologic features, paleontological sites, and caves. The Division's Geologic Resource Evaluation Program works with parks to identify geologic resources and issues, and provides the park with digital geologic map coverage and a park-specific geologic report. In a number of parks, geologic monitoring has also been established to track changes in geologic processes.
The NPS works in partnership with academia, the general public, industry, and volunteers to develop and improve its geologic resource management programs. Cooperative agreements have been established with amateur and professional geologic societies, as well as museums, colleges and universities to facilitate the identification and management of geologic resources.