Rocks & The Rock Cycle

rock

Earth material made of a mixture of one or more minerals, glass, minerialoids, or organic matter

The Rock Cycle

the processes by which, over many years, Earth's materials form and change back and forth among igneous rocks, sedimentary rocks, and metamorphic rocks

igneous rock

rock formed by the cooling and hardening of molten material from a volcano or from deep inside the Earth

sedimentary rock

rock formed when fragments of rocks, minerals, and/or organic matter are compacted or cemented together or precipitated out of solution

metamorphic rock

rock formed from sedimentary, igneous, or other metamorphic rock due to increases in heat or pressure

lava

molten rock from a volcano flowing onto Earth's surface

intrusive igneous rock

igneous rock formed when magma cools below Earth's surface; generally has large mineral grains

extrusive igneous rock

igneous rock formed when magma extrudes onto Earth's surface and cools as lava; has a fine-grained texture

mafic magma

magma rich in iron and magnesium, and lower amounts of silica; forms a dense, dark-colored rock when it cools and hardens (sometimes referred to as basaltic magma)

felsic magma

magma rich in silica and oxygen, and lower amounts of iron and magnesium; forms a light-colored rock when it cools and hardens (sometimes referred to as granitic magma)

foliated texture

a type of metamorphic rock texture created where mineral grains flatten and line up in parallel bands

nonfoliated texture

a type of metamorphic rock texture created where mineral grains change, grow, and rearrange, but don't form bands

sediments

loose materials such as rock fragments, mineral grains, and bits of plants and animals that have been transported by wind, water, or glaciers

compaction

a sedimentary rock-forming process that occurs when layers of small sediments become compressed by the weight of layers above them

cementation

a sedimentary rock-forming process in which large sediments are glued together by mineral deposited between the sediments

organic matter

any material that originated as plant or animal tissue; decaying animals or plants that become sediment and a part of soils

evaporite

A chemical sedimentary rock consisting of minerals precipitated by evaporating waters, especially salt and gypsum.

precipitate

a chemical sedimentary rock that forms when minerals settle out of a liquid mixture and then compact into solid rock

regional metamorphism

a change in the texture, structure, or chemical composition of a rock due to changes in temperature and pressure over a large area, generally as a result of tectonic forces.

contact metamorphism

a change in the texture, structure, or chemical composition of a rock due to contact with magma.

batholith

largest intrusive igneous rock body that forms when magma being forced upward toward Earth's crust cools slowly and solidifies underground

breccia

sedimentary rock made up of rock fragments with sharp edges

chemical sedimentary rock

sedimentary rock that forms when minerals precipitate from a solution or settle from a suspension.

clastic sedimentary rock

sedimentary rock that forms when fragments of preexisting rocks are compacted or cemented together

concretion

nodule of rock with a different composition from that of the main rock body

conglomerate

a sedimentary rock composed of rounded gravel-size particles

dike

igneous rock feature formed when magma is squeezed into a vertical crack that cuts across rock layers and hardens underground

fossil

the trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock

laccolith

when magma pushes up the earth's surface and cools forming a dome

lava plateau

a wide, flat landform that resutls from repeated nonexplosive eruptions of lava that spead over a large area

metamorphism

to change form

organic sedimentary rock

sedimentary rock that forms from the remains of plants or animals

porphyritic texture

an igneous texture consisting of large crystals embedded in a matrix of much smaller crystals

sill

igneous rock feature formed when magma is squeezed into a horizontal crack between layers of rock and hardens underground

stock

Irregularly shaped pluton that is similar to a batholith but smaller, generally forms 10-30 km beneath Earth's surface, and cuts across older rocks.

stratification

stacks of sedimentary rock layers, built up by deposition of silt and other materials over time

volcanic neck

solid igneous core of a volcano left behind after the softer cone has been eroded