Geology unit 2 exam

Weathering

The physical breakdown and chemical alteration of rocks and minerals at or near earths surface.

Parent Material

The material that is chemically and mechanically weathered to yield sediment and soil.

Erosion

The removal of weathered materials from their source area by running water, wind, glaciers, and waves.

Differential Weathering

Weathering that occurs at different rates on rocks, thereby, yielding an uneven surface.

Mechanical Weathering

Disaggregation of rocks by physical processes that yields smaller pieces that retain the composition of the parent material.

Frost Action

The disaggregation of rocks by repeated freezing and thawing of water in cracks and crevasses.

Talus

Accumulation of coarse, angular rock fragments at the base of a slope

Pressure Release

A mechanical weathering process in which rocks that formed under pressure expand on being exposed at the surface

Exfoliation Dome

A large, rounded dome of rock resulting when concentric layers of rock are stripped from the surface of a rock mass

Thermal Expansion and Contraction

A type of mechanical weathering in which the volume of rock changes in response to heating and cooling

Salt Crystal Growth

A mechanical weathering process in which salt crystals growing in cracks and pores disaggregate rocks.

Chemical Weathering

The decomposition of rocks by chemical alterations of parent material

Solution

A reaction in which the ions of a substance become dissociated in a liquid and the solid substance dissolves

Oxidation

The reaction of oxygen with other atoms to form oxides or if water is present, hydroxides

Hydrolysis

The chemical reaction between hydrogen ions and hydroxyl ions of water and minerals ions.

Spheroidal Weathering

A type of chemical weathering in which corners and sharp edges of rocks weather more rapidly than flat surfaces, thus yielding spherical shapes.

Regolith

The layer of unconsolidated rock and mineral fragments and soil that covers most of the land surface

Soil

Weathered materials containing water, air, and humus that can support vegetation

Soil Horizon

A distinct soil layer that differs from other soil layers in texture, structure, composition, and color.

Laterite

A red soil, rich in iron or aluminum, or both, resulting from intense chemical weathering in the tropics.

Soil Degradation

Any process leading to a loss of soil productivity, may involve erosion, chemical pollution, or compaction

Sediment

Loose aggregate of solids derived by weathering from pre-existing rocks, or solids precipitated from solution by inorganic chemical processes or extracted from solution by organisms.

Sedimentary Rock

Any rock composed of sediment, such as limestone and sandstone

Depositional Environment

Any site such as a floodplain or beach where physical

Lithification

The process of converting sediment into sedimentary rock by compaction and cementation

Compaction

Reduction in the volume of a sedimentary repost that results from its own weight and the weight of any additional sediment deposited on top of it

Cementation

The process whereby minerals crystallize in the pore spaces of sediment and bind the loose particles together

Detrital Sedimentary Rock

Sedimentary rock made up of the solid particles (detritus) of preexisting rocks

Chemical Sedimentary Rock

Sedimentary rock made up of minerals that were dissolved during chemical weathering and later precipitated from seawater, more rarely lake water, or extracted from solution by organisms.

Biochemical Sedimentary Rock

Any sedimentary rock produced by the chemical activities of organisms

Carbonate Rock

Any rock, such as limestone and dolostone, made up mostly of carbonate minerals

Evaporite

Any sedimentary rock, such as rock salt, formed by inorganic chemical precipitation of minerals from evaporating water.

Sedimentary Facies

Any aspect of a sedimentary rock unit that makes it recognizably different from adjacent sedimentary rocks of the same or approximately the same age

Marine Transgression

The invasion of a coastal area or a continent by the sea, resulting from a rise in sea level or subsidence of the land

Marine Regression

The withdrawal of the sea from a continent or coastal area, resulting in the emergence of the land as sea level falls or the land rises with respect to sea level

Sedimentary Structure

Any feature in sedimentary rock that formed at or shortly after the time of deposition, such as cross-bedding, animal burrows, and mud cracks

Strata

Refers to layering in sedimentary rocks

Bed

An individual layer of rock, especially sediment or sedimentary rock

Cross- bedding

A type of bedding in which layers are deposited at an angle to the surface on which they accumulate, as in sand dunes

Graded Bedding

Sedimentary layer in which a single bed shows a decrease in grain size from bottom to top

Ripple Mark

Wavelike structure produced in granular sediment, especially sand, by unidirectional wind and water currents or by oscillating wave currents

Mud Crack

A crack in clay-rich sediment that forms in response to drying and shrinkage

Fossil

The remains or traces of once-living organisms

Metamorphic Rock

Any rock that has been changed from its original condition by heat, pressure, and the chemical activity of fluids, as in marble and slate

Metamorphism

The phenomenon of rocks changing as a result of heat, pressure, and fluids, so that they are in equilibrium with a new set of environmental conditions

Heat

An agent of metamorphism

Lithostatic Pressure

Pressure exerted on rocks by the weight of overlying rocks.

Differential Pressure

Pressure that is not applied equally to all sides of a rock body

Fluid Activity

An agent of metamorphism in which water and carbon dioxide promote metamorphism by increasing the rate of chemical reactions

Contact (Thermal) Metamorphism

Metamorphism of country rock adjacent to a pluton

Aureole

A zone surrounding a pluton in which contact metamorphism took place

Dynamic Metamorphism

Metamorphism in fault zones, where rocks, are subjected to high differential pressure

Regional Metamorphism

Metamorphism that occurs over a large area, resulting from high temperatures, tremendous pressure, and the chemical activity of fluids within the crust

Index Mineral

A mineral that forms within specific temperature and pressure ranges during metamorphism

Foliated Texture

A texture in metamorphic rocks in which platy and elongated minerals are aligned in a parallel fashion

Non foliated Texture

A metamorphic texture in which there is a no discernible preferred orientation of minerals

Metamorphic Zone

The region between lines of equal metamorphic intensity known as isograds

Metamorphic Facies

A group of metamorphic rocks characterized by particular minerals that formed under the same broad temperature and pressure conditions

Earthquake

Vibrations caused by the sudden release of energy, usually as a result of displacement of rocks along faults

Elastic rebound theory

An explanation for the sudden release of energy that causes earthquakes when deformed rocks fracture and rebound to their original undeformed condition

Seismology

The study of earthquakes

Seismograph

An instrument that detects, records, and measures the various waves produced by earthquakes

Focus

The site within earth where an earthquake originates and energy is released

Epicenter

The point on Earths surface directly above and earthquakes focus

P-Wave

A compressional, or push-pull wave; the fastest seismic wave and one that can travel through solids, liquids, and gasses; also called a primary wave

S-Wave

A shear face that moves material perpendicular to the directions of travel, thereby producing shear stresses in the material it moves through; also known as secondary waves S- waves travel only through solids

Rayleigh Wave (R-Wave)

A surface wave in which individual particles of material move in an elliptical path within a vertical plane oriented in the direction of wave movement

Love Wave (L-Wave)

A surface wave in which the individual particles of material move only back and forth in a horizontal plane perpendicular to the direction of wave travel

Intensity

The subjective measure of the kind of damage done by an earthquake, as well as people's reaction to it

Modified Mercalli Intensity Scale

A scale with values from I to XII used to characterize earthquakes based on damage.

Richter Magnitude Scale

An open-ended scale that measures the amount of energy released during an earthquake

Magnitude

The total amount of energy released by an earthquake and its source

Tsunami

A large sea wave that is usually produced by an earthquake, but can also result from submarine landslides and volcanic eruptions.

Discontinuity

A boundary across which seismic wave velocity or direction of travel changes abruptly, such as the mantle- core boundary

P-Wave Shadow Zone

An area between 103 and 143 degrees from an earthquake focus where little P-wave energy is recorded by seismographs

S- Wace Shadow Zone

Those areas more than 103 degrees from an earthquake focus where no S-waves are recorded

Mohorovicic Discontinuity (Moho)

The boundary between Earths crust and mantle

Geothermal Gradiant

Earth's temperature increase with depth; it averages 25 degrees celsius/ km near the surface but varies from area to area

Strike

The direction of a line formed by the intersection of an inclined plane and a horizontal plane

Dip

A measure of the maximum angular deviation of an inclined plane from horizontal

Fold

A type of geologic structure in which planar features in rock layers such as bedding and foliation have been bent

Anticline

A convex upward fold in which the oldest exposed rocks coincide with the fold axis and all strata dip away from the axis

Syncline

A down arched fold in which the youngest exposed rocks coincide with the fold axis and all strata dip toward the axis

Dome

A rather circular geologic structure in which all rock layers dip away from a central point and the oldest exposed rocks are in the dome's center

Basin

A circular fold in which all strata dip inward toward a central point and the youngest exposed strata are in the center

Fault

A fracture along which rocks on opposite sides of the fracture have moved parallel with the fracture surface

Fault Plane

A fault surface that is more or less planar

Hanging wall block

The block of rock that overlies a fault plane

Footwall block

The block of rock that lies beneath a fault plane

Dip-slip fault

A fault on which all movement is parallel with the dip of the fault plane

Normal Fault

A dip slip fault on which the hanging wall block has moved downward relative to the footwall block

Reverse fault

A dip slip fault on which the hanging wall block has moved upward relative to the footwall block

Thrust Fault

A type of reverse fault in which a fault plane dips less than 45 degrees

Strike-slip fault

A fault horizontal movement of blocks of rock on opposite sides of a fault plane

Oblique-slip fault

A fault showing both dip-slip and strike-slip movement