Geology

The theory that Earth's outer shell is divided into large rigid plates that move, collide, and separate on top of the semi-fluid asthenosphere. Plate interactions drive earthquakes, volcanism, mountain building, and the opening and closing of ocean basins over millions of years.

The continuous process by which rocks are created, transformed, destroyed, and reformed through igneous, sedimentary, and metamorphic pathways. Energy from Earth's interior and the Sun drives this cycle, ensuring that no rock type is permanent.

The foundational geological principle that the same natural laws and processes operating today have operated throughout Earth's history. Often summarized as 'the present is the key to the past,' it allows geologists to interpret ancient rocks by studying modern analogs.

The branch of geology concerned with the order, relative position, and age of layered sedimentary rocks. By applying principles such as superposition and lateral continuity, stratigraphy provides a framework for reconstructing Earth's chronological history.

The systematic process of classifying minerals based on physical and chemical properties such as hardness, luster, cleavage, crystal habit, color, streak, and specific gravity. Correct identification is fundamental to petrology, economic geology, and materials science.

The chronological framework that divides Earth's 4.6-billion-year history into hierarchical units including eons, eras, periods, and epochs. It is built from the fossil record, radiometric dating, and stratigraphic relationships, providing a common language for discussing deep time.

The processes by which molten rock (magma), gases, and ash are expelled from Earth's interior to its surface. Volcanism builds new crust, recycles materials, shapes landscapes, and can dramatically affect global climate through the injection of aerosols into the atmosphere.

Weathering is the in-place breakdown of rocks and minerals by physical, chemical, and biological agents, while erosion is the transportation of that weathered material by water, wind, ice, or gravity. Together they sculpt landscapes and produce the sediment that forms new sedimentary rocks.

The study of earthquakes and the propagation of seismic waves through Earth's interior. Seismology has revealed Earth's layered internal structure and provides critical data for earthquake hazard assessment, early warning systems, and underground nuclear test detection.

The process of recording the distribution, nature, and age relationships of rock units, structural features, and surficial deposits on a map. Geological maps are essential tools for resource exploration, land-use planning, hazard assessment, and scientific research.