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Weathering

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The disintegration and decomposition of rock at or near the surface of the Earth

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Chemical Weathering

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The processes by which the internal structure of a mineral is altered by theremoval and/or addition of elements

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Mechanical Weathering

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The physical disintegration of rock, resulting in smaller fragments

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Frost Wedging

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The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices

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Sheeting

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A mechanical weathering process that is characterized by the splitting off of slablike sheets of rock

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Exfoliation Dome

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A large, dome shaped structure, usually composed of granite, that is formed by sheeting

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Dissolution

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A common form of chemical weathering, it is the process of dissolving into a homogeneous solution, as when an acidic solution dissolves limestone

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Oxidation

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The removal of one or more electrons from an atom. So named because elements commonly combine with oxygen

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Hydrolysis

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A chemical weathering process in which minerals are altered by chemically reacting with water and acids

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Spheroidal Weathering

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Any weathering process that tends to produce a spherical shape from an initially blocky shape

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Differential Weathering

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The variation in the rate and degree of weathering caused by such factors as mineral makeup, degree of jointing, and climate

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Regolith

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The layer of rock and mineral fragments that nearly everywhere covers Earth's land surface

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Soil

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A combination of mineral and organic matter, water,and air; the portion of the regolith that supports plant growth

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Humus

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Organic matter in soil that is produced by the decomposition of plants and animals

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Parent Material

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The material on which a soil develops

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Horizon

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A layer in a soil profile

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Soil Profile

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A vertical section through a soil, showing the succession of the horizons and the underlying parent material

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Eluviation

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A washing out of fine soil components from the A horizon by downward- percolating water

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Leaching

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The depletion of soluble materials from the upper soil by downward -percolating water

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Solum

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The O,A,and B horizons in a soil profile. Living roots and other plant and animal life are largely confined to this zone

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Soil Taxonomy

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A soil classification system that consists of six hierarchical categories, based on observable soil characteristics. The system recognizes 12 soil orders

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Sedimentary Rocks

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Rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified

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Detrital Sedimentary Rocks

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Rocks that form from the accumulation of materials that originate and are transported as solid particles derived from both mechanical and chemical weathering

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Chemical Sedimentary Rocks

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Sedimentary rock consisting of material that was precipitated from water by either inorganic or organic means

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Organic Sedimentary Rocks

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Sedimentary rock composed of organic carbon from the remains of plants that died and accumulated on the floor of a swamp . Coal is the primary example

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Fissility

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The property of splitting easily into thin layers along closely spaced, parallel surfaces, such as bedding planes in shale

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Sorting

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The degree of similarity in particle size in sediment or sedimentary rock

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Biochemical

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A type of chemical sediment that forms when material dissolved in water is precipitated by water-dwelling organisms. Shells are the most common examples

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Evaporites

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A sedimentary rock formed of material deposited from solution by evaporation of the water

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Salt Flats

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A white crust on the ground that is produced when water evaporates and leaves behind its dissolved materials

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Diagenisis

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A collective term for all the chemical,physical, and biological changes that take place after sediments are deposited and during and after lithification

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Lithification

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The process, generally involving cementation and/or compaction, of converting sediments to solid rock

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Compaction

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A type of lithification in which the weight of overlying material compresses more deeply buried sediment. It is most important in the fine-grained sedimentary rocks such as shale

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Cementation

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One way in which sedimentary rocks are lithified. As material precipitates from water that percolates through the sediment, open spaces are filled and particles are joined into a solid mass

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Clastic Texture

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A sedimentary rock texture consisting of broken fragments of preexisting rock

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Nonclastic Texture

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A term for the texture of sedimentary rocks in which the minerals form a pattern of interlocking crystals

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Crystalline

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(Texture same as Nonclastic) Any natural solid with an ordered, repetitive atomic structure

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Environment of Deposition (Sedimentary Environment)

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A geographic setting where sediment accumulates. Each site is characterized by a particular combination of geologic processes and environmental conditions

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Facies

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A portion of rock until that possesses a distinctive set of characteristics that distinguishes it from other parts of the same unit

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Strata (Beds)

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Parallel layers of sedimentary rock

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Bedding Planes

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A nearly flat surface that separates two beds of sedimentary rock. Each bedding plane marks the end of one deposit and the beginning of another having different characteristics

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Cross-Bedding

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A structure in which relatively thin layers are inclined at an angle to the main bedding. Cross-bedding is formed bu currents of wind or water

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Graded Beds

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A sediment layer characterized by a decrease in sediment size from the bottom to the top

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Ripple Marks

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Small waves of sand that develop on the surface of a sediments layer by the action of moving water or air

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Mud Cracks

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A feature in some sedimentary rocks that forms when wet mud dries out, shrinks, and cracks

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Fossils

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The remains of organisms preserved from the geologic past

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Parent Rock

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The rock from which a metamorphic rock formed

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Metamorphism

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The changes in mineral composition and texture of a rock subjected to high temperatures and pressure within earth

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Mineralogy

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The study of minerals

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Metamorphic Grade

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The degree to which a parent rock changes during metamorphism. It varies from low grade (low temp low pressure) to high grade (high temp high pressure)

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Recrystallization

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The formation of new mineral crystals in a rock that tend to be larger than the original crystals

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Confining Pressure

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Stress that is applied uniformly in all directions

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Differential Stress

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Forces that are unequal in different directions

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Compressional Stress

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Differential stress that shortens a rock body

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Texture

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The size, shape, and distribution of the particles that collectively constitute a rock

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Foliation

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A term for linear arrangement of textural features often exhibited by metamorphic rocks

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Rock Cleavage

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The tendency of rocks to split along parallel, closely spaced surfaces. These surfaces are often highly inclined to the bedding planes in the rock

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Slaty Cleavage

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A type of foliation that is characteristic of slates, in which there is a parallel arrangement of fine-grained metamorphic minerals

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Schistosity

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A type of foliation that is characteristic of coarser-grained metamorphic rocks. Such rockshave a parallel arrangement of platy minerals such as the micas

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Gneissic Texture (Gneissic Banding)

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A texture of metamorphic rocks in which dark and light silicate minerals are separated, giving the rock a banded appearance

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Nonfoliated

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Metamorphic rocks that do not exhibit foliation

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Porphyoblastic Texture

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A texture of metamorphic rocks in which particularly large grains (porphyroblasts) are surrounded by a fine-grained matrix of other minerals

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Contact (Thermal) Metamorphism

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Changes in rock caused by the heat from a nearby magma body

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Aureole

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A zone or halo of contact metamorphism found in the country rock surrounding an igneous intrusion

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Hydrothermal Metamorphism

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Chemical attractions that occur as hot, ion-rich water circulates through fractures in rock

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Burial Metamorphism

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Low-grade metamorphism that occurs in the lowest layers of very thick accumulation of sedimentary rocks

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Subduction Zone Metamorphism

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High pressure, low temperature metamorphism that occurs where sediments are carried to great depths by a subducting plate

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Regional Metamorphism

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Metamorphism associated with large-scale mountain building

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Impact (Shock) Metamorphism

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Metamorphism that occurs where when meteorites strike Earth's surface

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Index Mineral

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A mineral that is a good indicator of the metamorphic environment in which it formed. Used to distinguish different zones of regional metamorphism

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Migmatite

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A rock exhibiting both igneous and metamorphic rock characteristics. Such rocks may form when light-colored silicate minerals melt and then crystallize, while the dark silicate minerals remain solid

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Metamorphic Facies

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A group of associated minerals that are use d to establish the pressure and temperatures at which rocks undergo metamorphism

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Numerical Date

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The number of years that have passed since an event occurred

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Relative Date

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A process of determining the chronological order of events by placing rocks and structures in their proper sequence or order

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Principle of Superposition

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A principle which states that in any undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below

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Principle of Original Horizontality

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A principle by which layers of sediment are generally deposited in a horizontal or nearly horizontal position

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Principle of Lateral Continuity

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The principle of lateral continuity states that layers of sediment initially extend laterally in all directions; in other words, they are laterally continuous

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Principle of Cross-Cutting Rrelationships

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The principle of cross-cutting relationships states that an igneous intrusion is always younger than the rock it cuts across

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Inclusion

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In mineralogy, an inclusion is any material that is trapped inside a mineral during its formation (rock with the intrusion in it is younger than the adjacent rock)

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Conformable

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Of, relating to, or being rock or sediment strata that were deposited either adjacent to each other or in vertical sequence without interruption by a disruptive or altering process such as erosion or folding

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Uncomformity

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A surface between successive strata representing a missing interval in the geologic record of time, and produced either by an interruption in deposition or by the erosion of depositionally continuous strata followed by renewed deposition

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Angular Unconformity

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An unconformity in which the older strata dip at a different angle (usually steeper) than the younger strata

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Disconformity

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Unconformity between parallel beds or strata

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Nonconformity

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A type of unconformity in which rocks below the surface of unconformity are either igneous or metamorphic

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Fossils

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The remains of organisms preserved from the geologic past

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Paleontology

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The study of life of the past as recorded by fossil remains

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Correlation

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The determination of the equivalence or contemporaneity of geologic events in separated areas

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Principle of Fossil Succession

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The principle of faunal succession, also known as the law of faunal succession, is based on the observation that sedimentary rock strata contain fossilized flora and fauna, and that these fossils succeed each other vertically in a specific, reliable order that can be identified over wide horizontal distances

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Index Fossil

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a fossil that is useful for dating and correlating the strata in which it is found

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Fossil Assemblage

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The overlapping ranges of a group of fossils (assemblage) collected from a layer. By examining such an assemblage, the age of the sedimentary layer can be established

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Radioactivity

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spontaneous disintegration or decay of the nucleus of an atom by emission of particles, usually accompanied by electromagnetic radiation

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Radiometric Dating

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Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they formed

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Half-Life

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is the time required for the amount of something to fall to half its initial value

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Radiocarbon Dating

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Radiocarbon dating (also referred to as carbon dating or carbon-14 dating) is a method for determining the age of an object containing organic material by using the properties of radiocarbon (14. C), a radioactive isotope of carbon

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Geologic Time Scale

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is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships between events that have occurred throughout Earth's history

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Eon

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the largest unit in the geologic time scale

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Phanerozoic

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is a period of geological history that spans 542 million years (abundant fossil evidence)

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Era

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a long and distinct period of history with a particular feature or characteristic

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Paleozic

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was a time of dramatic geological, climatic, and evolutionary change (b/w Precambrian and Mesozoic 542-251 million years ago)

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Mesozoic

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The dinosaurs and the mammals appeared during the Triassic period, roughly 225 million years ago. The dinosaurs went extinct 65 million years ago. The Mesozoic Era lasted about 180 million years, and is divided into three periods, the Triassic, the Jurassic, and the Cretaceous

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Cenozoic

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The Cenozoic period began about 65 million years ago with the extinction of the dinosaurs and continues through the present. The Cenozoic is divided into just two time periods: the Tertiary, and the Quaternary

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Period

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Basic unit in geologic time that is a subdivision of an era

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Epoch

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Subdivision of a period

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Archean

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First eon of the Precambrian time. Preceding the Proterozoic. B/w 4.5 and 2.5 billion years ago

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Proterzoic

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Following the Archean and preceding the Phanerozoic. B/w 2500 and 542 million years ago

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Precambrian

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All time prior to the Phanerozoic eon. Encompasses the Archean and Proterzoic eons

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Deformation

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the action or process of changing in shape or distorting, especially through the application of pressure

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Rock Structure (Geologic Structure)

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All features created by deformation

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Confining Pressure

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Stress that is applied uniformly in all directions

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Differential Stress

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Forces that are unequal in different directions

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Compressional Stress

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Differential stress that shortens a rock body

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Tensional Stress

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Force per unit area acting on any surface within a solid

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Shear

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a strain in the structure of a substance produced by pressure, when its layers are laterally shifted in relation to each other (stress causes two layers to slide past one another)

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Strain

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irreversible change in the shape and size of a rock body caused by stress

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Elastic Deformation

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A temporary shape change that is self-reversing after the force is removed, so that the object returns to its original shape

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Brittle Deformation

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Generally, rocks respond to stress in one of two ways: they break, or they bend. When a rock breaks, it is called brittle deformation

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Ductile Deformation

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When rocks bend or flow, like clay, it is called ductile deformation

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Joint

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Fracture in rock with which there has been no movement

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Fault

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A break in a rock mass along which movement has occured

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Fold

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A bent layer or series of layers that were originally horizontal

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Anticline

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Fold in a sedimentary strata that resembles an arch

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Syncline

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Linear downfold in strata; opposite of Anticline

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Dome

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Roughly circular upfolded structure

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Basin

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Circular downfolded structure

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Monocline

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One limbed texture in a strata. The strata are usually flat-lying or very gently dipping on both sides of the monocline

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Fault

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A break in a rock mass along which movement has occured

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Dip-Slip Fault

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A fault in which the movement is parallel to the dip of the fault

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Hanging Wall Block

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The rock surface immediately above a fault

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Footwall Block

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The rock surface below a fault

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Fault Scarp

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A cliff created by movement along a fault. Represents the exposed surface of the fault prior to modification by weathering and erosion

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Normal Fault

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A fault in which the rock above the fault plane has moved down relative to the rock below

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Fault- Block Mountain

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A mountain that has formed by the displacement of rock along a fault

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Horst

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An elongate, uplifted block of crust bounded by faults

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Graben

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A valley formed by the downward displacement of a fault-bounded block

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Half- Graben

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A tilted fault block in which the higher side is associated with mountainous topography and the lower side is a basin that fills with sediment

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Detachment Fault

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A nearly horizontal fault that may extend for hundreds of kilometers below the surface. Such a fault represents a boundary between rocks that exhibit ductile deformation and rocks and rocks that exhibit brittle deformation

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Reverse Fault

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A fault in which the material above the fault plane moves up in relation to the material below

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Thrust Fault

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A low angle reverse fault

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Klippe

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A remnant or an outlier of a thrust sheet that was located by erosion

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Strike- Slip Fault

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A fault along which movement occurs horizontally

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Transform Fault

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Major spike strip fault that cuts through lithosphere and accommodates motion between two plates

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Joint

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Fracture in rock with which there has been no movement

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Oblique- Slip Fault

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A fault that exhibits both dip-slip and strike -slip movement

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Strike

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The compass direction of the line of intersection created by dipping bed or fault and a horizontal surface. A strike is always perpendicular to the direction of dip

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DIp

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The angle at which a rock layer or fault is inclined from the horizontal. The direction of dip is at a right angle to the strike

Geology Test 2- Paula Anderson – Flashcards

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