Why do earthquakes, volcanoes, floods, and landslides happen? What causes mountains to rise? How do beautiful landscapes develop? How have climate and life changed through time? When did the Earth form, and by what process? Where do we dig to find valuable metals, and where do we drill to find oil? Does sea level change? Do continents move? The study of geology addresses these important questions and many more. But from the birth of the discipline, in the late 18th century, until the mid-20th century, geologists considered each question largely in isolation, without pondering its relation to the others.

The 12th edition of Essentials of Geology, like its predecessors, is a college-level text for students taking their first and perhaps only course in geology. The text is intended to be a meaningful, nontechnical survey for people with little background in science. Usually students are taking this class to meet a portion of their college’s or university’s general requirements.
In addition to being informative and up-to-date, a major goal of Essentials of Geology is to meet the need of beginning students for a readable and user-friendly text; a text that is a highly usable tool for learning the basic principles and concepts of geology <...>

Petrology, from the Greek words petra , meaning rock, and logos, meaning knowledge, is the study of rocks and the conditions in which they form. It includes igneous, metamorphic, and sedimentary petrology.

To produce materials from mine to market it is necessary to overcome obstacles that include the force of gravity, the strength of molecular bonds, and technological inefficiencies. These challenges are met by the application of energy to accomplish the work that includes the direct use of electricity, fossil fuel, and manual labor. The tables and analyses presented in this study contain estimates of electricity consumption for the mining and processing of ores, concentrates, intermediate products, and industrial and refined metallic commodities on a kilowatt-hour (kWh) per unit basis, primarily the metric ton (ton) or troy ounce. Data contained in tables pertaining to specific currently operating facilities are static, as the amount of electricity consumed to process or produce a unit of material changes over time for a great number of reasons. Estimates were developed from diverse sources that included feasibility studies, company-produced annual and sustainability reports, conference proceedings, discussions with government and industry experts, journal articles, reference texts, and studies by nongovernmental organizations (NGOs). Suggestions for additions and corrections are welcome by the author. <...>