A

• Abyssal plain
  Abyssal plain
  An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3000 and 6000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth’s surface. They are among the flattest, smoothest...
  
  - Flat or very gently sloping areas of the deep ocean basin floor.
• Absolute dating
  Absolute dating
  Absolute dating is the process of determining an approximate computed age in archaeology and geology. Some scientists prefer the terms chronometric or calendar dating, as use of the word "absolute" implies an unwarranted certainty and precision...
  
  - the process of determining a specific date (in years or some other unit of time) for an archaeological, geological or paleontological site or artifact.
• Accretion
  Accretion (geology)
  Accretion is a process by which material is added to a tectonic plate or a landmass. This material may be sediment, volcanic arcs, seamounts or other igneous features.-Description:...
  
  - a process by which material is added to a tectonic plate.
• Aftershock
  Aftershock
  An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...
  
  - Small earthquake that follows a main shock.
• Alkaline - a highly basic substance that dissolves in water.
• Allochthonous - a large block of rock which has been moved from its original site of formation, usually by low angle thrust faulting.
• Alluvial fan
  Alluvial fan
  An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...
  
  - a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain.
• Alluvium
  Alluvium
  Alluvium is loose, unconsolidated soil or sediments, eroded, deposited, and reshaped by water in some form in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel...
  
  - soil or sediments deposited by a river or other running water.
• Amber
  Amber
  Amber is fossilized tree resin , which has been appreciated for its color and natural beauty since Neolithic times. Amber is used as an ingredient in perfumes, as a healing agent in folk medicine, and as jewelry. There are five classes of amber, defined on the basis of their chemical constituents...
  
  - name for fossil resin or tree sap that is appreciated for its colour.
• Andesite
  Andesite
  Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
  
  - fine-grained igneous rock of intermediate composition. Up to half of the rock is plagioclase feldspar with the rest being ferromagnesian minerals.
• Angular unconformity - an unconformity in which younger strata overlie an erosion surface on tilted of folded layered rock.
• Anticline
  Anticline
  In structural geology, an anticline is a fold that is convex up and has its oldest beds at its core. The term is not to be confused with antiform, which is a purely descriptive term for any fold that is convex up. Therefore if age relationships In structural geology, an anticline is a fold that is...
  
  - an arched fold in which the layers usually dip away from the axis.
• Aquifer
  Aquifer
  An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...
  
  - a body of saturated rock or sediment through which water can move readily.
• Aragonite sea
  Aragonite sea
  An aragonite sea contains aragonite and high-magnesium calcite as the primary inorganic carbonate precipitates. Therefore, the chemical conditions of the seawater must be notably high in magnesium content for an aragonite sea to form...
  
  - contains aragonite and high-magnesium calcite as the primary inorganic carbonate precipitates.
• Archean Eon - the oldest eon of the Earth's history.
• Archipelago
  Archipelago
  An archipelago , sometimes called an island group, is a chain or cluster of islands. The word archipelago is derived from the Greek ἄρχι- – arkhi- and πέλαγος – pélagos through the Italian arcipelago...
  
  - a chain or cluster of islands.
• Asphalt
  Asphalt
  Asphalt or , also known as bitumen, is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits, it is a substance classed as a pitch...
  
  - sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits.
• Asthenosphere
  Asthenosphere
  The asthenosphere is the highly viscous, mechanically weak and ductilely-deforming region of the upper mantle of the Earth...
  
  - a region of the Earth's outer shell beneath the lithosphere. The asthenosphere is of indeterminate thickness and behaves plastically.
• Autochthonous - rock which has not been moved from its original site of formation.

B

• Banded Iron Formation
  Banded iron formation
  Banded iron formations are distinctive units of sedimentary rock that are almost always of Precambrian age. A typical BIF consists of repeated, thin layers of iron oxides, either magnetite or hematite , alternating with bands of iron-poor shale and chert...
  
  - distinctive type of rock often found in primordial sedimentary rocks.
• Basalt
  Basalt
  Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
  
  - fine-grained, mafic, igneous rock composed predominantly of ferromagnesian minerals and with lesser amounts of calcium-rich plagioclase feldspar.
• Basement rock
  Basement Rock
  Basement or Basement Rock music was a sub-genre coined in 2006 in an article by music magazine TGR. This was first in relation to the existence of underground record label Criminal Records but more for the independent bands they represent. The roots of the sub-genre are noted to be as far back as...
  
  - the thick foundation of ancient, and oldest metamorphic and igneous rock that forms the crust of continents, often in the form of granite.
• Basin
  Drainage basin
  A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
  
  - rock formation scooped out by water erosion.
• Basin and Range Province - particular type of topography that covers much of the southwestern United States and northwestern Mexico that is typified by elongate north-south trending arid valleys bounded by mountain ranges which also bound adjacent valleys.
• Batholith
  Batholith
  A batholith is a large emplacement of igneous intrusive rock that forms from cooled magma deep in the Earth's crust...
  
  - a large discordant pluton with an outcropping area greater than 100 square kilometers.
• Bedrock
  Bedrock
  In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
  
  - native consolidated rock underlying the surface of a terrestrial planet, usually the Earth.
• Bioerosion
  Bioerosion
  Bioerosion describes the erosion of hard ocean substrates – and less often terrestrial substrates – by living organisms. Marine bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish; it can occur on coastlines, on coral reefs, and...
  
  - the erosion of hard ocean substrates by living organisms through a number of mechanisms.
• Biostratigraphy
  Biostratigraphy
  Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. Usually the aim is correlation, demonstrating that a particular horizon in one geological section represents the same period...
  
  - branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.
• Biostratinomy
  Biostratinomy
  Biostratinomy is the study of the processes that take place after an organism dies but before its final burial. It is considered to be a subsection of the science of taphonomy, along with necrology and diagenesis...
  
  - study of the processes that take place after an organism dies but before its final burial.
• Bioturbation
  Bioturbation
  In oceanography, limnology, pedology, geology , and archaeology, bioturbation is the displacement and mixing of sediment particles and solutes by fauna or flora . The mediators of bioturbation are typically annelid worms , bivalves In oceanography, limnology, pedology, geology (especially...
  
  - displacement and mixing of sediment particles by benthic fauna (animals) or flora (plants).
• Blueschist
  Blueschist
  Blueschist is a rock that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to ~500 degrees Celsius....
  
  - rock that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures, approximately corresponding to a depth of 15 to 30 kilometers and 200 to ~500 degrees Celsius.
• Brackish - water that has more salinity than fresh water, but not as much as seawater.
• Boudin
  Boudinage
  thumb|Boudinaged quartz vein in shear foliation, Starlight Pit, Fortnum Gold Mine, Western Australia.Boudinage is a geological term for structures formed by extension, where a rigid tabular body such as a bed of sandstone, is stretched and deformed amidst less competent surroundings...
  
  - geological term used for structures formed by extension, where a rigid tabular body such as a bed of sandstone, is stretched and deformed amidst less competent
  Competence (geology)
  In geology competence refers to the degree of resistance of rocks to either erosion or deformation in terms of relative mechanical strength. In mining 'competent rocks' are those in which an unsupported opening can be made. Competent rocks are more commonly exposed at outcrop as they tend to form...
  
   beds. See also Boudinage
  Boudinage
  thumb|Boudinaged quartz vein in shear foliation, Starlight Pit, Fortnum Gold Mine, Western Australia.Boudinage is a geological term for structures formed by extension, where a rigid tabular body such as a bed of sandstone, is stretched and deformed amidst less competent surroundings...
  
  .
• Bowen's reaction series
  Bowen's reaction series
  Within the field of geology, Bowen's reaction series is the work of the petrologist, Norman L. Bowen who was able to explain why certain types of minerals tend to be found together while others are almost never associated with one another...
  
  - the sequence in which minerals crystallize from a cooling basaltic magma.
• Fold Buckling (geology) - typically, folding is thought to occur by simple buckling of a planar surface and its confining volume. The volume change is accommodated by layer parallel shortening the volume, which grows in thickness.
• Buckling (mechanics)
  Buckling
  In science, buckling is a mathematical instability, leading to a failure mode.Theoretically, buckling is caused by a bifurcation in the solution to the equations of static equilibrium...
  
  - a failure mode of a rock subjected to high compressive stresses, where the actual compressive stress at the point of failure is less than the ultimate compressive stresses that the material is capable of withstanding.

C

• Calcareous
  Calcareous
  Calcareous is an adjective meaning mostly or partly composed of calcium carbonate, in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.-In zoology:...
  
  - sediment, sedimentary rock, or soil type which is formed from or contains a high proportion of calcium carbonate in the form of calcite or aragonite.
• Calcite sea
  Calcite sea
  A calcite sea is one in which low-magnesium calcite is the primary inorganic marine calcium carbonate precipitate. An aragonite sea is the alternate seawater chemistry in which aragonite and high-magnesium calcite are the primary inorganic carbonate precipitates...
  
  - one in which low-magnesium calcite is the primary inorganic marine calcium carbonate precipitate.
• Caldera
  Caldera
  A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters...
  
  - volcanic feature formed by the collapse of land following a volcanic eruption.
• Carbon film
  Carbon film
  Carbon films are a type of fossil, or preservation. They are thin film coatings which consist predominantly of the chemical element carbon, which include plasma polymer films, amorphous carbon films , CVD diamond films as well as graphite films. The tissue of organisms are made of compounds that...
  
  - type of fossil, or preservation.
• Carbonate
  Carbonate
  In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
  
  - a salt or ester of carbonic acid.
• Carbonate hardgrounds
  Carbonate hardgrounds
  Carbonate hardgrounds are surfaces of synsedimentarily cemented carbonate layers that have been exposed on the seafloor . A hardground is essentially, then, a lithified seafloor. Ancient hardgrounds are found in limestone sequences and distinguished from later-lithified sediments by evidence of...
  
  - surfaces of synsedimentarily-cemented carbonate layers that have been exposed on the seafloor.
• Casting
  Casting
  In metalworking, casting involves pouring liquid metal into a mold, which contains a hollow cavity of the desired shape, and then allowing it to cool and solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process...
  
  - manufacturing process by which a liquid material such as a suspension of minerals as used in ceramics or molten metal or plastic is introduced into a mould, allowed to solidify within the mould, and then ejected or broken out to make a fabricated part.
• Cenozoic Era - the most recent of the eras; followed the Mesozoic Era.
• Chalk
  Chalk
  Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
  
  - soft, white, porous sedimentary rock, a form of limestone composed of calcite coccolith
  Coccolith
  Coccoliths are individual plates of calcium carbonate formed by coccolithophores which are arranged around them in a coccosphere.- Formation and composition :...
  
   plates.
• Chert
  Chert
  Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
  
  - fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils.
• Clast - composed of fragments, or clasts, of pre-existing rock.
• Cleavage
  Cleavage (geology)
  This article is about rock cleavage, for cleavage in minerals see Cleavage Cleavage, in structural geology and petrology, describes a type of planar rock feature that develops as a result of deformation and metamorphism. The degree of deformation and metamorphism along with rock type determines the...
  
  - in structural geology and petrology, term describing the tendency of a rock to break along preferred planes of weakness, caused by the development of a planar fabric as a result of deformation.
• Coccolith
  Coccolith
  Coccoliths are individual plates of calcium carbonate formed by coccolithophores which are arranged around them in a coccosphere.- Formation and composition :...
  
  - individual plates of calcium carbonate formed by coccolithophore
  Coccolithophore
  Coccolithophores are single-celled algae, protists, and phytoplankton belonging to the division of haptophytes. They are distinguished by special calcium carbonate plates of uncertain function called coccoliths , which are important microfossils...
  
  s (single-celled algae such as Emiliania huxleyi
  Emiliania huxleyi
  Emiliania huxleyi, often abbreviated "EHUX", is a species of coccolithophore with a global distribution from the tropics to subarctic waters. It is one of thousands of different photosynthetic plankton that freely drift in the euphotic zone of the ocean, forming the basis of virtually all marine...
  
  ) which are arranged around them in a coccosphere.
• Coccolithophore
  Coccolithophore
  Coccolithophores are single-celled algae, protists, and phytoplankton belonging to the division of haptophytes. They are distinguished by special calcium carbonate plates of uncertain function called coccoliths , which are important microfossils...
  
  - (also called coccolithophorid) - important microfossils: single-celled algae, protists and phytoplankton belonging to the division of haptophytes. They are distinguished by special calcium carbonate plates called coccolith
  Coccolith
  Coccoliths are individual plates of calcium carbonate formed by coccolithophores which are arranged around them in a coccosphere.- Formation and composition :...
  
  s.
• Compactions - process by which a newly deposited sediment progressively loses its original water content due to the effects of loading, this forms part of the process of lithification.
• Compression
  Compression (geology)
  In geology the term compression refers to a set of stresses directed toward the center of a rock mass. Compressive strength refers to the maximum compressive stress that can be applied to a material before failure occurs. When the maximum compressive stress is in a horizontal orientation, thrust...
  
  - system of forces that tend to decrease the volume of or shorten rocks.
• Concretion
  Concretion
  A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity . Concretions are often ovoid or spherical in shape, although irregular shapes also occur. The word 'concretion' is derived from the Latin con meaning 'together' and crescere meaning 'to grow'...
  
  - volume of sedimentary rock in which a mineral cement fills the porosity (i.e. the spaces between the sediment grains).
• Conglomerate
  Conglomerate (geology)
  A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
  
  - rock consisting of individual stones that have become cemented together.
• Continental crust
  Continental crust
  The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...
  
  - layer of granitic, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves.
• Continental margin
  Continental margin
  The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. Continental margins constitute about 28% of the oceanic area....
  
  - zone of the ocean floor that separates the thin oceanic crust from thick continental crust.
• Continental shelf
  Continental shelf
  The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
  
  - extended perimeter of each continent and associated coastal plain, which is covered during interglacial periods such as the current epoch by relatively shallow seas (known as shelf seas) and gulfs.
• Convergent boundary
  Convergent boundary
  In plate tectonics, a convergent boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide...
  
  - boundary between two plates that are moving toward each other.
• Copal
  Copal
  Copal is a name given to tree resin that is particularly identified with the aromatic resins used by the cultures of pre-Columbian Mesoamerica as ceremonially burned incense and other purposes...
  
  - type of resin produced by plant or tree secretions, particularly identified with the forms of aromatic tree resins used by the cultures of pre-Columbian Mesoamerica as a ceremonially burned incense, as well as for a number of other purposes.
• Coprolites - fossil that results when human or animal dung is fossilized.
• Core
  Planetary core
  The planetary core consists of the innermost layer of a planet.The core may be composed of solid and liquid layers, while the cores of Mars and Venus are thought to be completely solid as they lack an internally generated magnetic field. In our solar system, core size can range from about 20% to...
  
  - innermost layer(s) of a planet.
• Craton
  Craton
  A craton is an old and stable part of the continental lithosphere. Having often survived cycles of merging and rifting of continents, cratons are generally found in the interiors of tectonic plates. They are characteristically composed of ancient crystalline basement rock, which may be covered by...
  
  - old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years.
• Cross-bedding
  Cross-bedding
  In geology, the sedimentary structures known as cross-bedding refer to horizontal units that are internally composed of inclined layers. This is a case in geology in which the original depositional layering is tilted, and the tilting is not a result of post-depositional deformation...
  
  - inclined sedimentary structures in a horizontal unit of rock; such tilted structures indicate the type of depositional environment, not post-depositional deformation.
• Crude oil - a liquid mixture of naturally occurring hydrocarbons.
• Crust
  Crust (geology)
  In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
  
  - outermost solid shell of Earth planet, or of any other planet or moon.

D

• Dacite
  Dacite
  Dacite is an igneous, volcanic rock. It has an aphanitic to porphyritic texture and is intermediate in composition between andesite and rhyolite. The relative proportions of feldspars and quartz in dacite, and in many other volcanic rocks, are illustrated in the QAPF diagram...
  
  - an igneous, volcanic rock with a high iron content.
• Daughter product - the isotope produced by radioactive decay.
• Delta
  River delta
  A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...
  
  - landform where the mouth of a river flows into an ocean, sea, desert, estuary, lake or another river.
• Dendrites
  Dendrite (crystal)
  A crystal dendrite is a crystal that develops with a typical multi-branching tree-like form. Dendritic crystal growth is very common and illustrated by snowflake formation and frost patterns on a window. Dendritic crystallization forms a natural fractal pattern...
  
  - crystal that develops with a typical multi-branching tree-like form.
• Deposition
  Deposition (geology)
  Deposition is the geological process by which material is added to a landform or land mass. Fluids such as wind and water, as well as sediment flowing via gravity, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of...
  
  - geological process by which material is added to a landform or land mass.
• Detachment fault
  Detachment fault
  Detachment faulting is associated with large-scale extensional tectonics. Detachment faults often have very large displacements and juxtapose unmetamorphosed hanging walls against medium to high-grade metamorphic footwalls that are called metamorphic core complexes...
  
  - major fault in a mountain belt above which rocks have been intensely folded or faulted.
• Diagenesis
  Diagenesis
  In geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration and metamorphism. These changes happen at relatively low temperatures and pressures...
  
  - chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration (weathering) and metamorphism.
• Diapir
  Diapir
  A diapir is a type of intrusion in which a more mobile and ductily-deformable material is forced into brittle overlying rocks. Depending on the tectonic environment, diapirs can range from idealized mushroom-shaped Rayleigh-Taylor instability-type structures in regions with low tectonic stress...
  
  - a type of intrusion in which a more mobile and ductily-deformable material is forced into brittle overlying rocks.
• Diatomite - naturally occurring, soft, chalk-like sedimentary rock that is easily crumbled into a fine white to off-white powder.
• Diorite
  Diorite
  Diorite is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar , biotite, hornblende, and/or pyroxene. It may contain small amounts of quartz, microcline and olivine. Zircon, apatite, sphene, magnetite, ilmenite and sulfides occur as accessory...
  
  - grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar (typically andesine), biotite, hornblende, and/or pyroxene.
• Dike
  Dike (geology)
  A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
  
  - or dyke - a type of sheet intrusion referring to any geologic body that cuts discordantly across.
• Dip slope
  Dip slope
  A dip slope is a geological formation often created by erosion of tilted strata. Dip slopes are found on homoclinal ridges with one side that is steep and irregular and another side, the dip slope, that is generally planar with a dip parallel to the bedding...
  
  - geological formation often created by erosion of tilted strata.
• Disconformity - a surface that represents missing rock strata but beds above and below that surface are parallel to one another.
• Divergent plate boundary - boundary separating two plates moving away from each other.
• Dolomite
  Dolomite
  Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
  
  - name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate CaMg(CO₃)₂ found in crystals.
• Drill core - drill specifically designed to remove a cylinder of material, much like a hole saw.
• Drumlin
  Drumlin
  A drumlin, from the Irish word droimnín , first recorded in 1833, is an elongated whale-shaped hill formed by glacial ice acting on underlying unconsolidated till or ground moraine.-Drumlin formation:...
  
  - an elongated whale-shaped hill formed by glacial action.
• Dyke
  Dike (geology)
  A dike or dyke in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across* planar wall rock structures, such as bedding or foliation...
  
  - or dike - a type of sheet intrusion referring to any geologic body that cuts discordantly across.

E

• Eon - the largest unit of geologic time.
• Epicenter
  Epicenter
  The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates...
  
  - point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or other underground explosion originates.
• Epoch
  Epoch (reference date)
  In the fields of chronology and periodization, an epoch is an instance in time chosen as the origin of a particular era. The "epoch" then serves as a reference point from which time is measured...
  
  - each period of the standard geologic time scale is divided into epochs (e.g., Pleistocene Epoch of the Quaternary Period).
• Erosion
  Erosion
  Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
  
  - displacement of solids (sediment, soil, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement in response to gravity or by living organisms (in the case of bioerosion
  Bioerosion
  Bioerosion describes the erosion of hard ocean substrates – and less often terrestrial substrates – by living organisms. Marine bioerosion can be caused by mollusks, polychaete worms, phoronids, sponges, crustaceans, echinoids, and fish; it can occur on coastlines, on coral reefs, and...
  
  ).
• Erratic
  Glacial erratic
  A glacial erratic is a piece of rock that differs from the size and type of rock native to the area in which it rests. "Erratics" take their name from the Latin word errare, and are carried by glacial ice, often over distances of hundreds of kilometres...
  
  -piece of rock that deviates from the size and type of rock native to the area in which it rests; the name "erratic" is based on the errant location of these boulders.
• Escarpment
  Escarpment
  An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...
  
  - transition zone between different physiogeographic provinces that involves an elevation differential, characterized by a cliff or steep slope.
• Esker
  Esker
  An esker is a long winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North America...
  
  - long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North America. Eskers are frequently several miles in length and, because of their peculiar uniform shape, somewhat resemble railroad embankments.
• Estuary
  Estuary
  An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
  
  - semi-enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea.
• Evaporite
  Evaporite
  Evaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...
  
  - water-soluble, mineral sediments that result from the evaporation of bodies of surface water.
• Exfoliation
  Exfoliation (geology)
  Exfoliation joints or sheet joints are surface-parallel fracture systems in rock often leading to erosion of concentric slabs.- General characteristics of exfoliation joints :* Commonly follow topography ....
  
  - the stripping of concentric rock slabs from the outer surface of a rock mass.
• Extension - strain involving an increase in length. Extension can cause thinning and faulting.
• Extrusive - mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff.

F

• Fanning
  Fanning
  Fanning can refer to:* Tabuaeran, also known as Fanning Atoll or Fanning Island, one of the Line Islands of the central Pacific Ocean.* Fanning , a revolver shooting technique in which one hand holds the revolver and the other hits the revolver hammer repeatedly for an increased rate of fire.*...
  
  - rock deformation related to shear stress
  Shear stress
  A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...
  
  
• Fault - discrete planar rock fracture, which shows evidence of a displacement. A fault is a discrete surface.
• Fault zone - zone where exist different discrete fault planes.
• Feldspars - group of most common minerals of the Earth's crust. All feldspars contain silicon, aluminum, and oxygen and may contain potassium, calcium and sodium.
• Felsic
  Felsic
  The word "felsic" is a term used in geology to refer to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium....
  
  - silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.
• Ferromagnesian mineral - iron/magnesium bearing mineral, such as augite, hornblende, olivine or biotite.
• Fold
  Fold (geology)
  The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in...
  
  - stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i.e. permanent) deformation.
• Foliation
  Foliation
  In mathematics, a foliation is a geometric device used to study manifolds, consisting of an integrable subbundle of the tangent bundle. A foliation looks locally like a decomposition of the manifold as a union of parallel submanifolds of smaller dimension....
  
  - parallel alignment of textural and structural features of a rock.
• Fossil
  Fossil
  Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
  
  - mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms.
• Fracture
  Fracture
  A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...
  
  - general non geological term used to indicate a crack or a discontinuity. Can only be used when no displacement can be distinguished. Vague term to avoid.
• Freezing
  Freezing
  Freezing or solidification is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. The reverse process is melting....
  
  - process whereby a liquid turns to a solid when cold enough.

G

• Gabbro
  Gabbro
  Gabbro refers to a large group of dark, coarse-grained, intrusive mafic igneous rocks chemically equivalent to basalt. The rocks are plutonic, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
  
  - dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt.
• Gastroliths - rocks, which are or have been held inside the digestive tract of an animal.
• Geologic maps - special-purpose map made to show geological features.
• Glass
  Glass
  Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
  
  - hard, brittle, transparent solid, such as used for windows, many bottles, or eyewear, including soda-lime glass, acrylic glass, sugar glass, isinglass (Muscovy-glass), or aluminium oxynitride.
• Gondwanaland - the southern part of Pangaea that formed South America, Africa, India, Australia and Antarctica.
• Granite
  Granite
  Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
  
  - common and widely occurring type of intrusive, felsic, igneous rock.
• Granodiorite
  Granodiorite
  Granodiorite is an intrusive igneous rock similar to granite, but containing more plagioclase than orthoclase-type feldspar. Officially, it is defined as a phaneritic igneous rock with greater than 20% quartz by volume where at least 65% of the feldspar is plagioclase. It usually contains abundant...
  
  - intrusive igneous rock similar to granite, but contains more plagioclase than potassium feldspar.
• Graywacke - variety of sandstone generally characterized by its hardness, dark color, and poorly-sorted, angular grains of quartz, feldspar, and small rock fragments set in a compact, clay-fine matrix.

H

• Half-life
  Half-life
  Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
  
  - the time it takes for a given amount of a radioactive isotope to be reduced by one-half.
• Hinge
  Hinge
  A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation. Hinges may be made of flexible material or of moving components...
  
  - zone of maximum curvature of a fold
  Fold (geology)
  The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in...
  
  .
• Hinge line - a line joining the points of maximum curvature along the hinge
  Hinge
  A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation. Hinges may be made of flexible material or of moving components...
  
   of a fold
  Fold (geology)
  The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in...
  
  .
• Hot springs
  Hot Springs
  Hot Springs may refer to:* Hot Springs, Arkansas** Hot Springs National Park, Arkansas*Hot Springs, California**Hot Springs, Lassen County, California**Hot Springs, Modoc County, California**Hot Springs, Placer County, California...
  
  - spring that is produced by the emergence of geothermally-heated groundwater from the Earth's crust.
• Hydrothermal vent
  Hydrothermal vent
  A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots. Hydrothermal vents exist because the earth is both...
  
  - fissure in a planet's surface from which geothermally heated water issues.
• Hypersaline - saltiness or dissolved salt content of a body of water.

I

• Ichnology
  Ichnology
  Ichnology is the branch of geology that deals with traces of organismal behavior, such as burrows and footprints. It is generally considered as a branch of paleontology; however, only one division of ichnology, paleoichnology, deals with trace fossils, while neoichnology is the study of modern traces...
  
  - branch of biology that deals with traces of organismal behavior.
• Igneous rock
  Igneous rock
  Igneous rock is one of the three main rock types, the others being sedimentary and metamorphic rock. Igneous rock is formed through the cooling and solidification of magma or lava...
  
  - rocks formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.
• Interbedded - beds (layers) of rock lying between or alternating with beds of a different kind of rock.
• Intrusion
  Intrusion
  An intrusion is liquid rock that forms under Earth's surface. Magma from under the surface is slowly pushed up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the rock slowly...
  
  - body of igneous rock that has crystallized from molten magma below the surface of the Earth.
• Island arc
  Island arc
  An island arc is a type of archipelago composed of a chain of volcanoes which alignment is arc-shaped, and which are situated parallel and close to a boundary between two converging tectonic plates....
  
  - chain of volcanic islands or mountains formed by plate tectonics as an oceanic tectonic plate subducts under another tectonic plate and produces magma.
• Isotope
  Isotope
  Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
  
  - different forms of an element each having different atomic mass (mass number).

J

• Join
  Join
  Join may refer to:* Join , to include additional counts or additional defendants on an indictment* Join , a least upper bound of set orders in lattice theory* Join , a type of binary operator...
  
  - discrete discontinuity surface without evidence of displacement. See also diaclase or bedding
  Bed (geology)
  In geology a bed is the smallest division of a geologic formation or stratigraphic rock series marked by well-defined divisional planes separating it from layers above and below. A bed is the smallest lithostratigraphic unit, usually ranging in thickness from a centimeter to several meters and...
  
  .
• Jurassic
  Jurassic
  The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
  
  - major unit of the geologic timescale that extends from about 199.6 ± 0.6 Ma (million years ago) to 145.4 ± 4.0 Ma, the end of the Triassic to the beginning of the Cretaceous.

K

• Kame
  Kame
  A kame is a geological feature, an irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depression on a retreating glacier, and is then deposited on the land surface with further melting of the glacier...
  
  - geological feature, an irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depression on a retreating glacier, and is then deposited on the land surface with further melting of the glacier.
• Karst
  KARST
  Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...
  
  - landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite.
• Kettle - fluvioglacial landform occurring as the result of blocks of ice calving
  Ice calving
  Ice calving, also known as glacier calving or iceberg calving, is a form of ice ablation or ice disruption. It is the sudden release and breaking away of a mass of ice from a glacier, iceberg, ice front, ice shelf, or crevasse...
  
   from the front of a receding glacier and becoming partially to wholly buried by glacial outwash.
• Kink
  Kink
  * A twist or bend in something such as rope, cable, hair or IG curveKink or KINK can refer to:* Kink , a colloquial term for non-normative sexual behavior...
  
  - tight curl, twist, or bend in a rock band. See also fold
  Fold (geology)
  The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of permanent deformation. Synsedimentary folds are those due to slumping of sedimentary material before it is lithified. Folds in rocks vary in...
  
  ing and buckling
  Buckling
  In science, buckling is a mathematical instability, leading to a failure mode.Theoretically, buckling is caused by a bifurcation in the solution to the equations of static equilibrium...
  
  .
• Kink band - an asymmetric, linear zone of deformation characterised by a tight curled, twisted, or bended rock band. Kink bands may also occur as conjugated sets.
• Klastos - (Greek: klastos= broken in pieces)composed of broken pieces of older rocks. Common term "Clastic".

L

• Lava
  Lava
  Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
  
  - molten rock expelled by a volcano during an eruption.
• Limestone
  Limestone
  Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
  
  - sedimentary rock composed largely of the mineral calcite (calcium carbonate: CaCO₃).
• Liquefaction
  Liquefaction
  Liquefaction may refer to:* Liquefaction, the general process of becoming liquid* Soil liquefaction, the process by which sediments become suspended* Liquefaction of gases in physics, chemistry, and thermal engineering* Liquefactive necrosis in pathology...
  
  - Soil liquefaction describes the behavior of soils that, when loaded, suddenly suffer a transition from a solid state to a liquefied state, or having the consistency of a heavy liquid.
• Loess
  Loess
  Loess is an aeolian sediment formed by the accumulation of wind-blown silt, typically in the 20–50 micrometre size range, twenty percent or less clay and the balance equal parts sand and silt that are loosely cemented by calcium carbonate...
  
  - fine, silty, pale yellow or buff in color, windblown (eolian) type of unconsolidated deposit.
• Lowland
  Lowland
  In physical geography, a lowland is any broad expanse of land with a general low level. The term is thus applied to the landward portion of the upward slope from oceanic depths to continental highlands, to a region of depression in the interior of a mountainous region, to a plain of denudation, or...
  
  - broad expanse of land with a general low level.

M

• Mafic
  Mafic
  Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term is a portmanteau of the words "magnesium" and "ferric". Most mafic minerals are dark in color and the relative density is greater than 3. Common rock-forming mafic minerals include olivine,...
  
  - a silicate mineral or rock that is rich in magnesium and iron.
• Magma
  Magma
  Magma is a mixture of molten rock, volatiles and solids that is found beneath the surface of the Earth, and is expected to exist on other terrestrial planets. Besides molten rock, magma may also contain suspended crystals and dissolved gas and sometimes also gas bubbles. Magma often collects in...
  
  - molten rock that sometimes forms beneath the surface of the earth (or any other terrestrial planet) that often collects in a magma chamber.
• Mantle
  Mantle (geology)
  The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....
  
  - highly viscous layer directly under the crust, and above the outer core.
• Marine terrace
  Marine terrace
  A marine terrace, coastal terrace, raised beach or perched coastline is a relatively flat, horizontal or gently inclined surface of marine origin, mostly an old abrasion platform which has been lifted out of the sphere of wave activity . Thus it lies above or under the current sea level, depending...
  
  - narrow flat area often seen at the base of a sea cliff caused by the action of the waves.
• Marl
  Marl
  Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
  
  - calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite.
• Mélange
  Mélange
  In geology, a mélange is a large-scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically consists of a jumble of large blocks of varied lithologies...
  
  - large scale breccia formed in the accretionary wedge above a subduction zone.
• Metamorphism
  Metamorphism
  Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
  
  - the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i.e. without melting.
• Micropaleontology
  Micropaleontology
  Micropaleontology is the branch of paleontology that studies microfossils.-Microfossils:...
  
  - branch of paleontology which studies microfossils.
• Mid-oceanic ridges - underwater mountain range, typically having a valley known as a rift running along its axis, formed by plate tectonics.
• Mineralization
  Mineralization (geology)
  In geology, mineralization is the hydrothermal deposition of economically important metals in the formation of ore bodies or "lodes".The first scientific studies of this process took place in Cornwall, United Kingdom by J.W.Henwood FRS and later by R.W...
  
  - hydrothermal deposition of economically important metals in the formation of ore bodies or "lodes".
• Molding
  Molding (process)
  Molding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model called a pattern....
  
  - process of manufacturing by shaping pliable raw material using a rigid frame or model called a mold.
• Moraine
  Moraine
  A moraine is any glacially formed accumulation of unconsolidated glacial debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past glacial maximum. This debris may have been plucked off a valley floor as a glacier advanced or it may have...
  
  - glacially formed accumulation of unconsolidated debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age.
• Mullion
  Mullion
  A mullion is a vertical structural element which divides adjacent window units. The primary purpose of the mullion is as a structural support to an arch or lintel above the window opening. Its secondary purpose may be as a rigid support to the glazing of the window...
  
  - a particuliar type of reworked boudin
  Boudinage
  thumb|Boudinaged quartz vein in shear foliation, Starlight Pit, Fortnum Gold Mine, Western Australia.Boudinage is a geological term for structures formed by extension, where a rigid tabular body such as a bed of sandstone, is stretched and deformed amidst less competent surroundings...
  
   (term likely derived from an architectural structure with the same name).

N

• Neogene
  Neogene
  The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...
  
  - a geologic period starting 23 million years ago and lasting either until today or ending 2.6 million years ago with the beginning of the Quaternary.
• Normal fault - Dip-slip faults can be sub-classified into the types "reverse" and "normal". A normal fault occurs when the crust is extended. Alternatively such a fault can be called an extensional fault. The hanging wall moves downward, relative to the footwall.

P

• Plate tectonics
  Plate tectonics
  Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
  
  (from the Greek
  Greek language
  Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
  
    τέκτων; tektōn, meaning "builder" or "mason") describes the large scale motions of Earth
  Earth
  Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
  
  's lithosphere
  Lithosphere
  The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...
  
  .
• Pelite
  Pelite
  Pelite is old and currently not widely used field terminology for a clayey fine-grained clastic sediment or sedimentary rock, i.e. mud or mudstone. It is equivalent to the Latin-derived term lutite. More commonly, metamorphic geologists currently use pelite for a metamorphosed fine-grained...
  
  - (Greek Pelos, Clay) - a descriptive name for a clastic rock with a grain size of less than 1/16 mm (originally sand or silt).
• Plumose -
• Porphyry
  Porphyry (geology)
  Porphyry is a variety of igneous rock consisting of large-grained crystals, such as feldspar or quartz, dispersed in a fine-grained feldspathic matrix or groundmass. The larger crystals are called phenocrysts...
  
  -
• Psammite
  Psammite
  Psammite is a general term for sandstone. It is equivalent to the Latin-derived term arenite. Also, it is commonly used in various publications to describe a metamorphosed sedimentary rock with a dominantly sandstone protolith. In Europe, this term was formerly used for a fine-grained, fissile,...
  
  - (Greek Psammos, Sand) - a general term for a sandstone, most often used to describe a metamorphosed rock unit with a dominantly sandstone protolith.

Q

• Quaternary
  Quaternary
  The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
  
  - The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows after the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present.

R

• Reverse fault - Dip-slip faults can be sub-classified into the types "reverse" and "normal". A reverse fault (or thrust fault) occurs when the crust is compressed. The hanging wall moves upward, relative to the footwall.

S

• Sediment trap
  Sediment trap (geology)
  In geology, a sediment trap is any topographic depression where sediments substantially accumulate over time. The size of a sediment trap can vary from a small lagoon to a large basin such as the Persian Gulf....
  
  - a depression where sediments substantially accumulate over time.
• Shale
  Shale
  Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
  
  - a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.
• Shear zone
  Shear zone
  A shear zone is a very important structural discontinuity surface in the Earth's crust and upper mantle. It forms as a response to inhomogeneous deformation partitioning strain into planar or curviplanar high-strain zones. Intervening blocks stay relatively unaffected by the deformation...
  
  - a tabular to sheetlike, planar or curviplanar zone composed of rocks that are more highly strained than rocks adjacent to the zone. See also Fault.
• Slickenside
  Slickenside
  thumb|Slickensides on a sample of sandstone of the [[Juniata Formation]], from an outcrop on [[U.S. Route 322|Rt 322]] northeast of State College, Pennsylvania250px|thumb|left|How slickenfibre steps form and show sense of movement on a fault...
  
  - a smoothly polished surface caused by frictional movement between rocks along the two sides of a fault. This surface is normally striated in the direction of movement.
• Schist
  Schist
  The schists constitute a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is...
  
  - group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. In the French, schist must be understood as shale
  Shale
  Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
  
  .
• Soil liquefaction
  Soil liquefaction
  Soil liquefaction describes a phenomenon whereby a saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid....
  
  - process describing the behavior of soils that, when loaded, suddenly suffer a transition from a solid state to a liquefied state, or having the consistency of a heavy liquid.
• Stylolite
  Stylolite
  Stylolites are serrated surfaces at which mineral material has been removed by pressure dissolution, in a process that decreases the total volume of rock. Insoluble minerals like clays, pyrite, oxides remain within the stylolites and make them visible...
  
  - an irregular discontinuity or non-structural fracture in limestone and other sedimentary rocks. Stylolites result from compaction and pressure solution during diagenesis.

T

• Tethys Ocean
  Tethys Ocean
  The Tethys Ocean was an ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.-Modern theory:...
  
  - (Greek: Τηθύς) - ocean that existed between the continents of Gondwana and Laurasia during the Mesozoic era before the opening of the Indian Ocean.

U

• Urchin
  Sea urchin
  Sea urchins or urchins are small, spiny, globular animals which, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. They inhabit all oceans. Their shell, or "test", is round and spiny, typically from across. Common colors include black and dull...
  
  - or sea urchin - small, spiny, globular animal belonging to the class of Echinoidea. Urchins inhabit all oceans. Their shell, or "test", is round and spiny, typically from 3 to 10 centimetres (1.2 to 3.9 in) across.
• Urgonian -

V

• Variscan orogeny
  Variscan orogeny
  The Variscan orogeny is a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica and Gondwana to form the supercontinent of Pangaea.-Naming:...
  
  - or Hercynian orogeny - is a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea.
• Vein
  Vein
  In the circulatory system, veins are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart...
  
  -
• Verging -
• Vitrinite
  Vitrinite
  Vitrinite is one of the primary components of coals and most sedimentary kerogens. Vitrinite is a type of maceral, where "macerals" are organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass . It is derived from the cell-wall material or...
  
  -
• Vug
  Vug
  Vugs are small to medium-sized cavities inside rock that may be formed through a variety of processes. Most commonly cracks and fissures opened by tectonic activity are partially filled by quartz, calcite, and other secondary minerals. Open spaces within ancient collapse breccias are another...
  
  -

W

• Wenlock
  Wenlock
  Wenlock may refer to:Places* Little Wenlock, Shropshire, England* Wenlock Edge, limestone escarpment near Much Wenlock* Much Wenlock, Shropshire, England** Wenlock ** Much Wenlock and Severn Junction railway...
  
  -
• Wiggle
  Wiggle
  Wiggle may refer to:*The Wiggle, a bike route in San Francisco that avoids steep grades*The Wiggles, an Australian children's band*Wiggle , an album by Screeching Weasel*Wiggle , a children's book by Doreen Cronin and Scott Menchin...
  
  - wave-shaped recorded log
  Log
  Log, LOG, or LoG may refer to:*Wooden log, also known as timber, wood from trees used for construction, fuel, or wood pulp for paper production...
  
  profiles.
• Wolframite
  Wolframite
  Wolframite WO4, is an iron manganese tungstate mineral that is the intermediate between ferberite and huebernite . Along with scheelite, the wolframite series are the most important tungsten ore minerals. Wolframite is found in quartz veins and pegmatites associated with granitic intrusives...
  
  - (Fe,Mn)WO₄ - an iron manganese tungstate mineral.

X

• Xenotime
  Xenotime
  Xenotime is a rare earth phosphate mineral, whose major component is yttrium orthophosphate . It forms a solid solution series with chernovite- and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium...
  
  - a rare earth phosphate mineral, whose major component is yttrium orthophosphate (YPO₄).
• XRD - X-ray diffraction - a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and diffracts into many specific directions.
• XRF
  X-ray fluorescence
  X-ray fluorescence is the emission of characteristic "secondary" X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays...
  
  - X-ray fluorescence - the emission of characteristic "secondary" (or fluorescent) X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays. The phenomenon is widely used for elemental analysis and chemical analysis of minerals.
• Xyloid coal - also known as lignite, often referred to as brown coal, is a soft brown fuel with characteristics that put it somewhere between coal and peat.

Y

• Yellow cake - or Yellowcake
  Yellowcake
  Yellowcake is a kind of uranium concentrate powder obtained from leach solutions, in an intermediate step in the processing of uranium ores. Yellowcake concentrates are prepared by various extraction and refining methods, depending on the types of ores...
  
   (also called urania) - a kind of uranium concentrate powder obtained from leach solutions, in an intermediate step in the processing of uranium ores.
• Young's modulus
  Young's modulus
  Young's modulus is a measure of the stiffness of an elastic material and is a quantity used to characterize materials. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law holds. In solid mechanics, the slope of the stress-strain...
  
  - in solid mechanics, Young's modulus, also known as the tensile modulus, is a measure of the stiffness of an isotropic elastic material. It is defined as the ratio of the uniaxial stress over the uniaxial strain in the range of stress in which Hooke's Law
  Hooke's law
  In mechanics, and physics, Hooke's law of elasticity is an approximation that states that the extension of a spring is in direct proportion with the load applied to it. Many materials obey this law as long as the load does not exceed the material's elastic limit. Materials for which Hooke's law...
  
   holds.
• Ypresian
  Ypresian
  In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....
  
  - In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between ~56 Ma and ~49 Ma (million years ago).

Z

• Zeolite
  Zeolite
  Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrik Cronstedt, who observed that upon rapidly heating the material stilbite, it produced large amounts of steam from water that...
  
  - microporous, aluminosilicate minerals commonly used as adsorbent.
• Zircon
  Zircon
  Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. A common empirical formula showing some of the range of substitution in zircon is 1–x4x–y...
  
  - a zirconium silicate mineral belonging to the group of nesosilicates. Its corresponding chemical formula is ZrSiO₄.