Geography

Cyanobacteria Definition Cyanobacteria are any of a phylum of photosynthetic bacteria that live in water or damp soil and were once thought to be plants.…

Stromatolite Definition Stromatolite is a dome-shaped structure consisting of alternating layers of carbonate or silicate sediment and fossilized algal mats. Stromatolites are one of the…

Porphyry Definition Porphyry is an igneous rock containing the large crystals known as phenocrysts embedded in a fine-grained matrix. The larger crystals are called phenocrysts.…

St Martin’s Island St Martin’s Island is a small island in the northeast of the bay of bengal, about 9 km south of the Cox’s…

Craton Definition Craton is a large portion of a continental plate that has been relatively undisturbed since the Precambrian era and includes both shield and…

Plate Tectonics Definition Plate tectonics is a theory that the Earth’s lithosphere (the crust and upper mantle) is divided into a number of large, platelike…

Earthquake Definition Earthquake is a sudden movement of the Earth’s lithosphere (its crust and upper mantle). Earthquakes are caused by the release of built-up stress…

Seismic Wave Definition Seismic wave is an elastic shock wave that travels through the earth, as from an earthquake or explosion; also, one of four…

Continental Crust Definition Continental crust is the solid, outermost layer of the Earth, lying above the mantle.  This layer is sometimes called sial because its…

Metamorphism Definition Metamorphism is the process by which rocks are changed in composition, texture, or structure by extreme heat and pressure. The change occurs primarily…

Metasomatism Definition Metasomatism is the process by which the chemical composition of a rock is changed through the introduction or extraction of chemicals dissolved in…

What is Permafrost? Permafrost is a thick subsurface layer of soil that remains frozen throughout the year, occurring chiefly in Polar Regions. It is defined…