A summary of the divisions of geologic time intended to provide a consistent time scale to be used in communicating ages of geologic units in the United States.
Revised geologic time scale indicating the ages of the lower bounds of chronostratigraphic and geochronologic units as they are currently known. Modifications to those ages made since the previous time scale was released (2007) are clearly marked.
Summaries of geologic projects in cooperation with the National Park Service including Grand Canyon National Park, Lake Mead National Recreation Area, Golden Gate National Recreation Area, Joshua Tree National Park, Yosemite National Park, and others.
Booklet giving general explanations of geologic time, major divisions of geologic time, relative and radiometric time scales, index fossils, and the age of the earth.
Coordinated studies of the effect of historical mining for mercury, origin and composition of metals in groundwaters and surface waters, history of volcanic and intrusive activity, and the complex geological history of this area.