earth science

rock

a naturally occurring, solid mass or hard bundle made of one or more minerals

rock cycle

a continuous, repeating process by which rocks on Earth change from one type into another

magma

an extremely hot mixture of molten or semi-molten rock, minerals, and dissolved gases

lava

molten or semi-molten rock that has erupted onto the surface of the Earth from a volcano or fracture in the crust

igneous rock

a type of rock formed when hot, melted rock cools down and turns solid

weathering

the breaking down of rocks, soils, and minerals on Earth's surface into smaller pieces or new substances

sediment

loose solid particles—such as rocks, minerals, or the remains of living things—that have been broken down

sedimentary rock

types of rock formed when pieces of older rocks, minerals, or living things settle in layers and are pressed and glued together over time

metamorphic rock

a type of rock that forms when an existing rock is changed deep underground by extreme heat and pressure without actually melting

intrusive igneous rock

a type of rock that forms when molten magma cools and solidifies slowly beneath the Earth's surface

extrusive igneous rock

a type of rock that forms when melted rock (lava) cools and hardens on the Earth's surface

texture

the size, shape, and arrangement of mineral grains, crystals, or particles that make up a rock or soil

granitic composition

a light-colored, coarse-grained igneous rock makeup that is rich in silica, potassium, sodium, and aluminum, and dominated by the minerals quartz and feldspar

basaltic composition

a dark-colored, fine-grained volcanic material that is rich in iron and magnesium and low in silica

andesitic composition

a type of volcanic rock or magma that is intermediate in its chemical makeup

erosion

the natural process of wearing away rock and soil and moving those pieces to a new location

deposition

the process where moving water, wind, ice, or gravity drops off bits of rock, soil, and sand in a new location

compaction

the process where the weight of overlying layers squeezes sediments together, reducing their volume and pushing out trapped water and air from the spaces between grains

cementation

the geological process where dissolved minerals precipitate out of groundwater and act as a natural glue, binding loose sediment grains together into solid rock

clastic sedimentary rock

a type of rock made from broken pieces (called clasts) of older, pre-existing rocks and minerals that have been pressed and glued together

chemical sedimentary rock

a type of rock that forms when minerals dissolved in water crystallize and settle out of solution

biochemical sedimentary rock

a type of rock that forms when living organisms extract dissolved minerals from water to build shells, bones, or tissues, which then accumulate and harden into stone after the organisms die

metamorphism

the process where an existing sedimentary rock changes into a new type of rock deep underground due to intense heat and pressure, without actually melting

contact metamorphism

happens when hot, molten magma bakes the nearby, cooler sedimentary rock, changing its mineral crystals and texture without melting it

regional metamorphism

a geological process where intense heat and pressure over a large area transform an existing sedimentary rock into a new metamorphic rock

hyrothermal solution

hot, mineral-rich water moving through the Earth's crust

foliated metamorphic rock

a rock that developed a layered or banded appearance because directed pressure squeezed and aligned its mineral crystals

nonfoliated metamorphic rock

a type of changed rock that does not have visible layers or bands