Introduction — Indian Plate The Indian plate is a minor tectonic plate situated across the equator in the Eastern Hemisphere whose status as a distinct plate has been subject to debate. It originated as part of the Gondwana supercontinent and rifted away roughly 100 million years ago, migrating northward while transporting the continental fragment often…
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Indian Ocean
Introduction The Indian Ocean is one of five cartographically defined oceanic divisions—alongside the Pacific, Atlantic, Arctic, and Southern/Antarctic Oceans—whose map boundaries are practical conventions rather than discrete geological separations. Within its basin are numerous marginal seas that occupy continental margins and impose distinct hydrographic and ecological conditions; notable examples include the Arabian Sea, the Bay…
Igneous Rock
Introduction Igneous rock—from the Latin igneus, “fiery”—constitutes one of Earth’s principal rock types and forms by the cooling and solidification of molten rock (magma or lava). Magma is generated by partial melting of pre‑existing mantle or crustal materials; melting is initiated principally by increases in temperature, reductions in pressure, or compositional changes such as volatile…
Human Evolution
Homo sapiens is one species within the hominid family of primates, a lineage that shares a single common ancestry with the other great apes and traces its roots across Africa and Asia. The emergence of anatomically modern humans reflects a suite of derived traits—habitual bipedalism, refined manual dexterity and capacities for complex symbolic communication—superimposed on…
Hoodoo (Geology)
A hoodoo is a slender, pillar-like rock formation produced by erosion; comparable features are commonly referred to as tent rocks, fairy chimneys, or earth pyramids. Morphologically, a hoodoo consists of a relatively soft-rock column capped by a more resistant stone whose greater durability retards downward erosion and thereby shields the underlying shaft. Such forms develop…
History Of The Big Bang Theory
Introduction Physical cosmology investigates the origin, large‑scale arrangement, composition, dynamics and ultimate fate of the Universe by combining theoretical models with empirical tests. The modern Big Bang paradigm—in which the cosmos evolves from an initially extremely hot, dense state and expands thereafter—was first cast into a quantitative framework by Georges Lemaître in 1927. Empirical support…
History Of Solar System Formation And Evolution Hypotheses
The scientific inquiry into the origin and evolution of the Solar System finds its formal roots in the Copernican Revolution, which reframed astronomical thought and established the conceptual basis for later theories of planetary formation and dynamics. The term “Solar System” itself appears in the literature by 1704, signalling the emergence of a modern planetary…
History Of Earth
Introduction The Geological Time Scale (GTS) is the internationally accepted framework for subdividing Earth history into named eons, eras and periods; it expresses ages in Ma (million years ago) and organizes geological and biological events into a standardized chronology from planetary formation to the present. Earth accreted from the solar nebula about 4.54 billion years…
Himalayas
The Himalayas are a dominant orographic feature of southern Asia, forming the principal physical barrier between the lowland Indo‑Gangetic Plain and the high Tibetan Plateau and containing some of the planet’s highest summits, including Mount Everest. Oriented along a west‑northwest to east‑southeast arc approximately 2,400 km long, the range is anchored by Nanga Parbat in…
Guyot
Introduction A guyot (pronounced /ˈɡiː.oʊ, ɡiːˈoʊ/; also called a tablemount) is a volcanic submarine landform defined by an isolated seamount whose summit is distinctly flattened and lies submerged more than 200 m (≈660 ft) below mean sea level. These flat tops can form extensive, relatively level platforms with diameters that may exceed 10 km (≈6…
Gravity Of Earth
Introduction Satellite gravimetry (notably NASA’s GRACE mission) maps departures of Earth’s gravity field from an idealized smooth reference surface—the terrestrial ellipsoid—revealing positive anomalies (stronger gravity; commonly shown in red) and negative anomalies (weaker gravity; shown in blue). These spatial variations reflect heterogeneity in Earth’s internal mass distribution and its temporal changes. The gravity of Earth…
Gondwana
Gondwana was a principal Paleozoic–Mesozoic continental assembly whose constituent cratons now form roughly two thirds of present-day continental area, including South America, Africa, Antarctica, Australia, Zealandia, Arabia and the Indian subcontinent. Its construction began in the Neoproterozoic, with accretionary collisions such as the East African Orogeny (c. 800–650 Ma) that sutured India and Madagascar to…
Glossary Of Landforms
Landform classification relies on a suite of observable, measurable physical attributes that together define a terrain feature’s identity and behaviour, enabling comparison across regions and scales beyond naming conventions. Chief among these attributes is origin: the formative agent (e.g., tectonic uplift, volcanism, fluvial processes, glaciation, coastal dynamics, aeolian transport, mass-wasting) largely determines a landform’s internal…
Glacier
Introduction A glacier is a persistent, concentrated mass of dense ice that behaves as a geomorphic material: it deforms internally and flows downslope under its own weight. Glaciers develop where multi‑year snow accumulation consistently exceeds ablation, yielding a self‑driven body of ice that transmits stress, moves, and progressively modifies its bed and surrounding landscape. Flow…
Geothermal Gradient
The geothermal gradient quantifies how temperature increases with depth within a planetary interior, commonly reported as °C km−1 (equivalently K km−1 or mK m−1). In stable continental crust away from plate boundaries this near-surface gradient is typically on the order of 25–30 °C km−1, implying a temperature rise of roughly 25–30 °C per kilometre. Atmospheric…
Geosyncline
Introduction The geosyncline was a nineteenth– and early twentieth–century framework for explaining orogeny in which vast, long-lived downward folds or troughs in the crust accumulated thick sedimentary sequences prior to mountain building. In this model, continued deposition within the trough created a heavy sediment pile that was later buoyantly readjusted—through processes described as isostatic uplift—so…
Geomorphosite
Geomorphosites — Introduction A geomorphosite is a landform or assemblage of landforms that attains significance beyond its physical form through scientific, educational, historic‑cultural, aesthetic or socio‑economic values, and thereby becomes an element of natural heritage warranting study, protection and interpretation. As a category, geomorphosites form a subset of geoheritage (geosites) and encompass a broad range…
Geomorphology
Geomorphology is the scientific study of the origin, form and evolution of Earth’s surface features—both continental topography and submarine bathymetry—shaped by physical, chemical and biological agents operating at or near the surface. The discipline’s name, from the Greek gê (earth), morphḗ (form) and lógos (study), underscores its central concern with landform form and the systematic…
Geomorphologist
Introduction Geomorphology is the scientific study of the shapes of Earth’s surface—both terrestrial topography and submarine bathymetry—and of the physical, chemical, and biological processes that create and modify those forms. Its central goals are to explain why landscapes look as they do, to reconstruct the history and dynamics of landforms, and to forecast how terrain…
Geology
Introduction Geology is the scientific study of the Earth and other planetary bodies, their constituent rocks and minerals, and the physical, chemical and biological processes that modify those materials through time. The term derives from Ancient Greek γῆ (gê), “earth,” and λoγία (-logía), “study of.” Modern geology is integrative, overlapping other Earth sciences (including hydrology),…
Geological History Of Earth
Introduction The geological time scale organizes Earth’s 4.54-billion-year history into hierarchical units—eons, eras, periods and epochs—providing a stratigraphy-based chronological framework often depicted as a “geological clock” that relates interval lengths to major geological and biological events. Earth accreted from the solar nebula, and in its earliest stages the planet was largely molten due to intense…
Geological History Of Borneo
Introduction Borneo, situated in Southeast Asia (map shows the island within the regional context and marks the Red River Fault as a component of the tectonic framework), rests on a composite basement formed during a protracted 400-million-year history of plate convergence. That basement records successive arc–continent and continent–continent collisions and repeated cycles of subduction and…
Geography Of Kaziranga National Park
Introduction Kaziranga National Park (Assamese: কাজিৰঙা ৰাষ্ট্ৰীয় উদ্যান, Kazirônga Rastriyô Uddyan, IPA: [kaziɹɔŋa ɹastɹijɔ udːjan]) is a protected unit of the Brahmaputra floodplain located in the Golaghat and Nagaon districts of Assam, India, and inscribed as a UNESCO World Heritage Site. The park is internationally important as the principal refuge for the world’s largest population…
Geode
Introduction A geode (pronounced /ˈdʒiː.oʊd/; from Ancient Greek γεώδης, “earthlike”) is a secondary geological structure occurring within both sedimentary and volcanic host rocks. Morphologically, geodes are roughly spherical to sub‑spherical nodules that enclose an internal hollow whose walls are commonly lined or partially infilled with mineral matter, frequently manifesting as crystal aggregates (quartz‑filled examples are…
GaláPagos Hotspot
The Galápagos hotspot is a long‑lived mantle upwelling beneath the eastern tropical Pacific that has generated the Galápagos Islands and three major aseismic ridges—Carnegie, Cocos and Malpelo. Located near the Equator on the Nazca Plate and adjacent to the Galápagos spreading centre, the hotspot sits within a complex plate environment dominated by the Galápagos triple…
Formation Of Rocks
Terrestrial rocks arise primarily by three end-member processes—accumulation and burial of particles, crystallization from molten material, and solid-state transformation under elevated pressure and temperature—which yield sedimentary, igneous, and metamorphic rocks, respectively. In addition to these planet-bound pathways, a fourth class—often termed primitive or condensate rock—forms directly from gas and dust in a protoplanetary disk and…
Formation And Evolution Of The Solar System
Introduction The Solar System formed roughly 4.6 billion years ago when a localized region within a giant molecular cloud collapsed under gravity. Most of the infalling material concentrated at the center to become the Sun, while the remainder flattened into a rotating protoplanetary disk whose solids and gas provided the ingredients for planets, moons, asteroids…
Foreshock
A foreshock is a smaller earthquake that precedes and is physically related in time and space to a subsequently larger mainshock; its role is defined by this temporal–spatial relationship within a seismic sequence rather than by a distinct faulting mechanism. Because a larger event may occur after an apparently isolated earthquake, labeling an event as…
Fordon Slope
Introduction — Fordon Slope The Fordon Slope is a distinct physical‑geographical microregion in northern Poland, situated in the Kuyavian‑Pomeranian Voivodeship and forming the southern and eastern fringe of the Świecie Upland mesoregion. Administratively it extends across the gminas of Bydgoszcz, Osielsko, Dobrcz, Pruszcz and Świecie, integrating peri‑urban and rural terrain and exerting a direct influence…
Fold Mountains
Introduction Fold mountains are orogenic belts formed when layered rocks in the upper crust undergo horizontal shortening, causing strata to buckle into anticlines and synclines and to be offset on thrust faults. Sustained compressive tectonic forces—most commonly at convergent plate margins—deform sedimentary and shallow crustal sequences, producing crustal thickening, regional uplift and the characteristic ridge‑and‑valley…
Fold (Geology)
Introduction In structural geology, folds are bent or curved arrangements of originally planar layers, such as sedimentary beds, whose geometries record the permanent deformation history of rocks. They range enormously in scale—from microscopic crinkles visible in hand specimens to mountain-scale structures—and may occur as isolated features or as regularly spaced sequences (fold trains). When folding…
Felsic
Felsic describes igneous silicate minerals, magmas, and rocks whose composition is dominated by silica- and alkali-bearing phases (principally feldspar and quartz) rather than iron‑ and magnesium‑rich minerals. Chemically, felsic systems are enriched in the lighter major elements—silicon, oxygen, aluminium, sodium, and potassium—which determine their characteristic mineralogy and melt chemistry. Typical felsic assemblages include quartz, muscovite,…
Fault (Geology)
Introduction A fault is a planar fracture or discontinuity in rock across which appreciable relative displacement has occurred; this displacement may take the form of sudden slip or gradual offset accumulated over time. Many large faults develop in the crust in response to plate‑tectonic stresses, and the largest among them demarcate plate boundaries—for example, megathrusts…
Falkner–Skan Boundary Layer
The Falkner–Skan boundary layer comprises a family of steady, two‑dimensional laminar boundary‑layer flows that develop along an inclined surface (a wedge), with similarity formulations introduced by Victor M. Falkner and Sylvia W. Skan. In such wedge geometries the plate’s inclination relative to the oncoming flow produces a longitudinal pressure gradient in the outer inviscid flow;…
Extremes On Earth
Introduction This compilation addresses planet‑scale geographical superlatives: individual locations that represent Earth‑wide extremes in geophysical or meteorological characteristics, explicitly excluding records that are only extreme within a single continent or nation. It encompasses positional extremes (absolute northernmost, southernmost, easternmost, westernmost points), vertical extremes (highest elevations above a defined sea level and lowest exposed basins), oceanic…