The mission of the U.S. Geological Survey (USGS) Water Resources Discipline is to provide the information and understanding needed for wise management of the Nation's water resources. Inherent in this mission is the responsibility of collecting data that accurately describe the physical, chemical, and biological attributes of water systems. These data are used for environmental and resource assessments by the USGS, other government agencies and scientific organizations, and the general public. Reliable and quality-assured data are essential to the credibility and impartiality of the water-resources appraisals carried out by the USGS.

As the importance and dependence of specific mineral commodities increase, so does concern about their supply. The United States is currently 100 percent reliant on foreign sources for 20 mineral commodities and imports the majority of its supply of more than 50 mineral commodities. Mineral commodities that have important uses and face potential supply disruption are critical to American economic and national security. However, a mineral commodity's importance and the nature of its supply chain can change with time; a mineral commodity that may not have been considered critical 25 years ago may be critical today, and one considered critical today may not be so in the future. The U.S. Geological Survey has produced this volume to describe a select group of mineral commodities currently critical to our economy and security. For each mineral commodity covered, the authors provide a comprehensive look at (1) the commodity's use; (2) the geology and global distribution of the mineral deposit types that account for the present and possible future supply of the commodity; (3) the current status of production, reserves, and resources in the United States and globally; and (4) environmental considerations related to the commodity's production from different types of mineral deposits. The volume describes U.S. critical mineral resources in a global context, for no country can be self-sufficient for all its mineral commodity needs, and the United States will always rely on global mineral commodity supply chains. This volume provides the scientific understanding of critical mineral resources required for informed decisionmaking by those responsible for ensuring that the United States has a secure and sustainable supply of mineral commodities.

This book focuses on the geological evolution of Southwest (SW) Gondwana and presents state-of-the-art insights into its evolution. It addresses the diachronic assembly of continental fragments derived from the break-up of the Rodinia supercontinent later amalgamated to build SW Gondwana during the Neoproterozoic–Cambrian transition, which on a global scale includes parts of present-day South America, Africa and Madagascar. The book presents 24 state-of-the-art reviews including the most crucial controversies. Most experienced scientists about the geology of SW Gondwana from Europe, Africa, South America and Australia present contributions on key areas addressing the interactions between the main cratons and fold belts on both sides of the South Atlantic Ocean. Chapters related to the geology of the major Archean- Paleoproterozoic cratons and Neoproterozoic Brasiliano/Pan-African fold belts enable readers to gain an in-depth understanding of the tectonometamorphic and magmatic evolution of SW Gondwana. The book covers a wide range of issues including metallogenetic, sedimentary, paleobiological and paleoclimatic processes and allows a deep insight into this key period of the Earth’s evolution.