Category: Geography

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…

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),…

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…

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…

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…

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…

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…

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…

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…

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…

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…

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…

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 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,…

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…

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;…

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…

Introduction The Explorer Plate is an oceanic fragment located off the western margin of Vancouver Island that is being actively consumed along a convergent boundary with the North American Plate; part of the plate is already subducting beneath the continental margin. Together with the Juan de Fuca and Gorda plates it constitutes a remnant of…

Introduction Exogeny (or exogeneity) designates processes, forces, or factors that originate outside a defined system and act upon it, producing change from the exterior rather than through internal mechanisms. The term stems from Greek roots meaning “outside” (ἔξω) and “to produce” (-γένεια), reflecting its character as externally sourced influence. In physical geography, exogenic processes operate…

Introduction The Eurasian Plate is one of Earth’s principal lithospheric plates, underlying the greater part of the combined European and Asian landmass and providing the structural basis for the region’s geology. It does not, however, carry all territory conventionally considered part of Eurasia: the Arabian Peninsula, the Indian subcontinent, and the area east of the…

Epicenter (Introduction) The epicenter is the surface point directly above an earthquake’s subsurface origin—commonly called the hypocenter or focus—and is variously spelled epicentre or epicentrum. The hypocenter specifies the three‑dimensional initiation point of rupture within the crust or mantle; its depth strongly influences the pattern of shaking at the surface, with shallow events producing more…

Epeirogenic movement — Introduction Epeirogenic movement refers to broad, long-wavelength vertical adjustments of continental crust that produce gentle regional uplift or subsidence rather than the intense folding and shortening characteristic of mountain belts. These phenomena typically affect the stable interior regions of continents (cratons), where the crust responds over large horizontal distances with subtle undulations…

The East Anatolian Fault (EAF; Turkish: Doğu Anadolu Fay Hattı) is a major strike‑slip fault system in Turkey, extending roughly 700 km from the eastern to the south‑central part of the country. Tectonically it functions as a transform boundary between the Anatolian sub‑plate and the northward‑moving Arabian plate, accommodating relative motion primarily through lateral displacement…

Introduction The East African Rift (EAR or EARS) is an active continental rift system in East Africa that began forming in the early Miocene (≈22–25 Ma) and was long considered the southern continuation of the so‑called Great Rift Valley. It represents a nascent divergent plate boundary along which the African Plate is fragmenting into the…

Introduction The Earth’s mantle is a thick silicate-rock shell lying between the crust and the outer core and constitutes a principal component of the planet’s internal structure. It has a mass of 4.01×10^24 kg—about 67% of Earth’s total mass—and extends roughly 2,900 km in depth, equivalent to ≈46% of Earth’s radius and nearly 84% of…

Three-dimensional visualizations of Earth’s magnetic field—showing field lines concentrated within the core and extending outward into space—emphasize that the field is produced internally yet shapes a large external magnetosphere. The source is the geodynamo in the electrically conducting outer core: buoyancy-driven convection of a molten iron–nickel alloy sets up electric currents that sustain the geomagnetic…

Introduction The Earth’s inner core is a roughly spherical central region composed predominantly of a solid iron–nickel alloy with smaller amounts of lighter elements, extending to a radius of about 1,230 km. This radius corresponds to roughly one-fifth of Earth’s total radius and is on the order of 70% of the Moon’s radius, indicating a…

Introduction An earthquake is the sudden shaking of Earth’s surface produced when elastic strain accumulated in the lithosphere is abruptly released, radiating seismic waves; events range from imperceptible tremors to catastrophic shocks that destroy infrastructure and cause mass casualties. The initial rupture point within the crust is termed the hypocenter (or focus), and its surface…

The notion of “earthquake weather” is a widespread folk belief that specific atmospheric conditions immediately precede seismic events, so that particular kinds of weather are interpreted as signals of an impending earthquake. Common vernacular descriptions include unusually hot or muggy air, prolonged calm or lack of wind, oppressive humidity, abrupt clearing after storms, or low…

An earthquake swarm is a temporally concentrated sequence of seismic events occurring within a limited geographical area over a relatively short interval—ranging from days to years—in which no single event clearly dominates as a mainshock. This behavior contrasts fundamentally with a classic mainshock–aftershock sequence, where one large event is followed by a decaying cluster of…

Introduction Earthquake lights—also termed earthquake lightning or earthquake flash—are luminous optical phenomena reported in close temporal and spatial association with seismic and volcanic events. They typically appear in the sky near areas of crustal strain such as active faults, earthquake epicenters, or erupting vents and arise during, immediately before, or shortly after episodes of seismicity…

Earth — Introduction Earth is the third planet from the Sun and the only known body in the Solar System that supports life. It is distinguished by globally persistent liquid surface water: the ocean contains almost all planetary water and covers about 70.8% of the crust, while the remaining 29.2% of the surface area is…

Introduction The Earth radius (R or R_E) denotes the linear distance from the planet’s center to a point on or near the surface. Under the common oblate‑spheroid approximation this distance varies with latitude and provides the primary link between a surface location, its vertical position, and many geodetic calculations. The spheroidal approximation is characterized by…

Introduction — Doublet (multiplet/twin) earthquakes Doublet or multiplet earthquakes are sequences in which two or more principal shocks originate from the same rupture zone and stress field and produce nearly identical seismic waveforms. They are distinguished from ordinary aftershocks by their similarity in size—typically within ~0.4 magnitude—and by their overlapping focal areas, which for very…

Introduction A divergent boundary—also termed a divergent plate boundary, constructive boundary, or extensional boundary—is a linear tectonic zone where two lithospheric plates move apart. When divergence occurs within continental crust it typically initiates rifting that may develop into rift valleys; where it occurs between oceanic plates the characteristic surface expression is the mid‑ocean ridge, which…