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[edit]Facies - The sum of the lithological and faunal characters of a sediment is its facies. Lithological facies involves composition, grain size, texture, colour, as well as such mass characteristics as current bedding, nature of stratification, ripple marks etc. Similarly metamorphic facies involves the degree of crystallisation and the mineral assemblage in a group of metamorphic rocks.Fanning - rock deformation related to shear stressFault - discrete planar rock fracture, which shows evidence of a displacement (the throw of the fault). 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.Fels - Massive metamorphic rock lacking schistosity or foliation.Felsic - silicate minerals, magmas, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Light minerals (Quartz & Feldspar) >60% - Acid. [Granite (Rhyolite), Adamellite (Rhyo-dacite), Granodiorite (Dacite)]. Mnemonic adjective for igneous rock having light coloured minerals in its mode. From Feldspar and Silica. Opposite to Mafic.Ferricrete - conglomerate consisting of surficial sand and gravel cemented into a hard mass by iron oxide derived from oxidation of percolating solution of iron salts. A ferruginous duricrust.Ferromagnesian mineral - iron/magnesium bearing mineral, such as augite, hornblende, olivine or biotite.Fission track dating - a method that uses tracks that are visible under the microscope to date minerals.Flandrian transgression -Fold - 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 - parallel alignment of textural and structural features of a rock.Fossil - mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms.Fossiliferous - bearing, or being composed of fossils in rocks or strata.Fracture - 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 - process whereby a liquid turns to a solid when cold enough.G[edit]Gabbro - 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.Geosyncline - A mobile down-warping of the crust of the earth, either elongate or basin-like, measured in scores of kilometres, which is subsiding as sedimentary and volcanic rocks accumulate to thicknesses of thousands of metres.Glass - 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.Glauconite - Hydrated silicate of potassium and iron, a green mineral that forms on submerged banks. Its occurrence in sands and sandstones is considered an indication of accumulation under marine conditions.Gneiss - Coarse-grained, pale-coloured gneissose rock, containing abundant feldspar