Download Rock Cycle Vocabulary

Rock Cycle Vocabulary
Rock Cycle: A series of processes that form igneous, sedimentary, and metamorphic rocks
Rock: Mixture of one or more types of minerals
Intrusive igneous rock: rock formed by magma that cools below Earth's surface
Extrusive igneous rock: rock formed by lava that cools on Earth's surface
Igneous rock: rock formed by magma that cools below Earth's surface
Igneous rocks:
Kinds of Igneous Rocks: Igneous Rocks are formed by crystallization from a liquid, or magma.
They include two types
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Volcanic or extrusive igneous rocks form when the magma cools and crystallizes on the
surface of the Earth
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Intrusive or plutonic igneous rocks wherein the magma crystallizes at depth in the Earth.
Magma is a mixture of liquid rock, crystals, and gas. Characterized by a wide range of
chemical compositions, with high temperature, and properties of a liquid.
Igneous rocks are those which crystallize from a silicate or other type of “magma” (molten
rock) either deep underground or near the surface.
Igneous rocks which form deep underground are called “plutonic” and igneous rocks which
occur near or at the surface are called “volcanic”.
Igneous rocks are composed mostly of crystals. It is the size of the crystals, called “grain size”,
which provides an important clue as to the origin of the igneous rock in a plutonic or volcanic
setting.
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Fast cooling on the surface results in many small crystals or quenching to a glass. Gives
rise to aphanitic texture (crystals cannot be distinguished with the naked eye), or
obsidian (volcanic glass).
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Slow cooling at depth in the earth results in fewer much larger crystals, gives rise to
phaneritic texture.
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Porphyritic texture develops when slow cooling is followed by rapid cooling.
Phenocrysts = larger crystals, matrix or groundmass = smaller crystals.
The general color of igneous rocks can also be used to identify the rocks. Charts based on color,
composition and texture
Sediments: small particles of mud, sand, or rock caused by rock weathering or erosion
Erosion: the wearing away of land surfaces
Weathering: the breakup of rocks from chemical reaction or mechanical agents
Sedimentary rock: rock formed when particles recombine into a new solid (Examples)
Limestone: Consists of carbonate minerals, primarily calcite and dolomite. Other
impurities can be abundant, such as quartz, clays, feldspar, or pyrite. Forms by different
processes in marine environment, shallow water and can contain abundant fossils.
Shale: Fine-grained rock formed by compaction of mud, silt and sand. Characterized by
fine laminate
Siltstone: Coarser-grained than shale in grain size. --Similar to shale in composition,
except for higher quartz content.
Sandstone: Medium-grained- consisting largely of quartz (85-90%) and various
impurities, some of which provide the cementing agent to bind the quartz grains together.
Conglomerate: Consists of gravel in a fine-grained matrix of sand, silt or other
particles. The gravel “clasts” may be round or angular, and are generally at least 2 millimeters in
diameter.
Coal: Consists of 50 – 70% carbonaceous - material derived from plants.
Compaction: sediments compress and form rock
Cementation: sediments compress and form rock
Chemical sedimentary rock: rock formed from dissolved minerals that become concentrated
when water evaporates
Metamorphic rock: rock formed when rock is changed by heat and/or pressure
Form by re crystallization of either igneous or sedimentary rocks. This happens when the
temperature, pressure or fluid environment change and a rock changes its form (e.g. limestone
turns to marble).
The range of temperatures for metamorphism is 150C up to the melting temperature.
The type of rock formed is controlled by the parent rock and the pressure/temperature
conditions.
Metamorphism causes growth of new minerals, rotation or deformation of mineral grains, and re
crystallization of minerals. The cycle is completed when the rocks melt again and become
magma.
Metamorphic Rocks (Examples)
Slate: Fine-grained and formed from shale---Characteristic breakage into slabs due to
slatey cleavage.
Phyllite: Fine-grained and contains very small flakes of sericite and chlorite, visible only
with a hand lens or by using a microscope. Characteristic “sheen” along cleavages,
Schist: Strongly foliated and containing larger crystals due to strong re crystallization.
Gneiss: Very coarse-grained, usually banded to some extent, and usually with a relatively
strong foliation.
Marble: Consists of re crystallized calcite or dolomite and forms from limestone.
Quartzite: Consists of re crystallized quartz and forms from sandstone.
Hornfels: Consists of re crystallized calcite and/or quartz and new minerals formed from
impurities
Foliated: texture of metamorphic rock whose grains are in parallel bands
Non-foliated- texture of metamorphic rock not in parallel bands
Elastic sediments: made of particles of various sized carried in suspension by wind, water or
ice. Sand is an example of an elastic rock.
Chemical sediments: precipitated from water. Halite (salt) is an example of a chemical rock.
Organic sediments: precipitated or accumulated by biological means. Many plants and animals
--- hard parts made for example of calcite and leave organic sediments behind. Limestone is an
example of organic sediment.
Fossils: the remains, impressions, or other evidence of the existence of plants and animals
preserved in rock
EARTH SYSTEMS- GEOLOGY
Aquifer an underground rock formation where water collects
Artesian water: ground water that is under pressure when tapped by a well and is able to rise
above the level at which it is first encountered
Condensation: The process by which water vapor changes from a gas to a liquid.
Drainage Area: The part of the aquifer where runoff water goes into streams and flows to the
recharge zone
Erosion: the process in which a material is worn away by a stream of liquid (water) or air
Evaporation the process of liquid water becoming water vapor, including vaporization from
water surfaces, land surfaces, and snow fields, but not from leaf surfaces
Impermeable layer: layer of solid material, such as rock or clay, which does not allow
water to pass through
Percolation: Water trickling downward through the cracks in rocks and pores in soil
Permeability: the ability of a material to allow the passage of a liquid, such as water through
rocks. Permeable materials, such as gravel and sand, allow water to move quickly through them
Rock Cycle: A series of processes that form igneous, sedimentary, and metamorphic rocks
Runoff: Water that is applied to the soil too quickly or for too long a time and thus
runs off and is wasted; does not get absorbed by soil
Saturated: An area of rock that is soaked with water
Surface water: water that is on the Earth's surface, such as in a stream, river, lake, or reservoir
Unsaturated: The zone immediately below the land surface where the pores contain both water
and air, but are not totally saturated with water. These zones differ from an aquifer, where the
pores are saturated with water.