magma
Molten rock generated from below Earth's crust, from which igneous rock is formed.
igneous rock
Rock that forms when magma rises to Earth's surface, cools, and solidifies.
weathering
The decomposition and disintegration of rocks and minerals at Earth's surface by chemical and physical processes.
sediment
Solid rock or mineral fragments that are transported and deposited by wind, water, gravity, or ice; that are weathered by natural forces, precipitated by chemical reactions, or secreted by organisms; and that accumulate in loose, unconsolidated layers.
sedimentary rock
Rock formed when sediment becomes cemented or compacted through the process of lithification.
metamorphic rock
A rock formed when igneous, sedimentary, or other metamorphic rock recrystallize in response to elevated temperature, increased pressure, chemical change, and/or deformation.
rock cycle
The sequence of events in which rocks are formed, destroyed, altered, and reformed by geological processes.
texture
The size, shape, and arrangement of minerals, grains, or crystals, in a rock.
extrusive igneous rock
Igneous rock formed from material that has erupted through the crust onto the surface of Earth; usually fine grained. Also called volcanic rock.
lava
Fluid magma that flows onto Earth's surface from a volcano or fissure. Also, the rock formed by solidification of the same material.
intrusive igneous rock
A rock formed when magma solidifies within Earth's crust, without erupting to the surface usually medium to coarse grained. Also called plutonic rock.
basement rock
The older igneous and metamorphic rock that lies beneath the thin layer fo sedimentary rocks and soil covering much of Earth's surface, forming the "___________" of the crust.
bedrock
The solid rock that lies beneath soil or unconsolidated sediments; it can be igneous, metamorphic, or sedimentary.
parent rock
Any original rock before it is changed by weathering, metamorphism, or other geological processes.
country rock
The older rock already in an area, cut into by a younger igneous intrusion or mineral deposit.
lithification
The process by which loose sediment is converted to solid rock.
precipitation
A chemical reaction that produces a solid rock, called precipitate, from a liquid solution.
pore space
The empty space between particles of rock, sediment, or soil.
compaction
Tight packing of sedimentary grains, usually resulting from the weight of overlying sediment, causing weak lithification and a decrease in porosity.
conglomerate
A classic sedimentary rock that consists of lithified gravel.
shale
A clastic sedimentary rock that consists of lithified tiny clay minerals and smaller amounts of quartz and organic particles. The organic material in ________ is the source of most oil and natural gas.
peat
A loose, unconsolidated, brownish mass of partially decayed plant matter; a precursor to coal.
carbonate rocks
Bioclastic sedimentary rocks composed of the carbonate minerals (minerals whose chemical elements include carbon and oxygen).
sedimentary structure
Any feature of sedimentary rock formed during deposition or by later sedimentary processes-for example, layering, ripple marks, or fossils.
bedding
Layering that develops as sediments are deposited; also called stratification.
cross-bedding
A sedimentary structure in which wind or water deposits small beds at an angle to the main sedimentary layering.
ripple marks
Small, parallel ridges and troughs formed in sediment by wind, water currents, or waves, which are often perserved when the sediment is lithified.
mud cracks
Irregular polygonal fractures that develop when mud dries, forming patterns that may be perserved when the mud is lithified.
fossil
The imprint, remains, or any other trace of a plant or animal perserved in rock.
metamorphism
The process by which rocks and minerals change form in response to changes in temperature, pressure, chemical conditions, and/or deformation.
metamorphic grade
The intensity of metamorphism that formed a rock; the maximum temperature and pressure attained during metamorphism.
foliation
The layering in micas and other minerals created by metamorphism.
slaty cleavage
A metamorphic foliation producing a parallel fracture pattern that cuts across original sedimentary bedding in micas or other metamorphic rocks.