EES 104 - Test 2 Review: Sedimentary, Metamorphic, Structural Geology, and Volcanism

Comprehensive vocabulary flashcards reviewing Sedimentary Rocks, Metamorphism, Structural Geology, and Volcanism for Test 2 in EES 104.

Weathering

The breakdown and alteration of rocks and minerals at or near Earth's surface through physical and chemical processes.

Erosion

The process by which weathered rock and mineral fragments are loosened and removed from their original site.

Sediment Transportation

The movement of detached sediment particles over distance by dynamic geologic agents such as water, wind, glacial ice, or gravity.

Deposition

The settling out or resting of transported sediment particles into a depositional environment when flow velocity or transport energy decreases.

Lithification

The conversion of unconsolidated sediments into solid sedimentary rock via compaction and cementation.

Detrital (Clastic) Sediments

Sediments made up of solid mineral and rock fragments produced by the mechanical breakdown and weathering of preexisting rocks.

Chemical Sediments

Sediments formed from dissolved ions that precipitate out of water solutions through chemical reactions or biochemical activity, such as limestone.

Sediment Texture

The descriptive physical properties of sediment grains, including grain size, rounding, and sorting, used to characterize detrital sediments.

Grain Size vs. Flow Velocity Relationship

Fast-flowing transport agents deposit coarse sediment grains, whereas slow-moving water deposits fine grains; grain sizes progressively decrease downstream with greater transport distance.

Rounding

The degree of smoothing and abrasion of sharp edges and corners on sediment grains, which increases with greater distance of transport.

Sorting

The degree of uniformity in the size of sediment grains in a deposit; wind produces very well-sorted deposits, whereas glacial ice produces poorly sorted till.

Sediment Maturity

A measure of the textural and compositional evolution of sediment, indicating long transport distances and prolonged weathering away from its source rock.

Compaction

The squeezing together of sediment particles under the weight of overlying layers, which reduces pore space and expels trapped water.

Cementation

The crystallization of dissolved minerals within the remaining pore spaces between sediment grains, binding them into solid sedimentary rock.

Primary Sedimentary Structures

Geologic features that develop in sediments during or immediately following deposition, such as bedding planes.

Secondary Sedimentary Structures

Features formed in sedimentary deposits after deposition has ended, such as desiccation cracks and trace fossils like dinosaur footprints.

Symmetric Wave Ripples

Bidirectional ripple bedforms produced by the oscillating, back-and-forth motion of water waves.

Asymmetric Current Ripples

Unidirectional ripple bedforms that reveal the specific flow direction of moving water or wind.

Desiccation Cracks

Secondary sedimentary fracture patterns that form when wet, muddy sediments shrink and crack as they dry out.

Protolith

The original parent rock that undergoes physical and chemical changes in the solid state to become a metamorphic rock.

Recrystallization

A metamorphic process wherein existing mineral grains change size and shape without changing their chemical composition or mineral identity.

Recombination

A metamorphic process where chemical components in the protolith react under heat and pressure to synthesize entirely new mineral species.

Foliated Metamorphic Rock

A metamorphic rock exhibiting a repetitive planar fabric, layering, or mineral banding developed through recombination under differential stress.

Non-foliated Metamorphic Rock

A metamorphic rock lacking a planar or banded texture, commonly produced by the recrystallization of monomineralic parent rocks, such as quartzite from sandstone or marble from limestone.

Confining Pressure

Equal, uniform stress applied to a rock in all directions from the weight of surrounding and overlying rock.

Differential Stress

Unequal directional forces applied to a rock body, resulting in compression, tension, or shearing.

Contact Metamorphism

Localized metamorphism driven predominantly by high temperatures from an intruding body of molten magma into adjacent country rock.

Cataclastic Metamorphism

Metamorphism resulting from mechanical shearing and intense crushing of rocks along active fault zones without high temperatures.

Regional Metamorphism

Widespread metamorphism driven by both high differential stresses and high temperatures over vast areas, typically at convergent tectonic boundaries.

Hydrothermal Metamorphism

Chemical alteration of rocks resulting from the circulation of hot, ion-rich water solutions through fractures.

Metamorphic Grade Sequence

The progressive order of foliated metamorphic rocks from lowest to highest metamorphic grade: slate, phyllite, schist, gneiss, and migmatite.

Structural Geology

The study of the three-dimensional geometry, deformation, architecture, and origin of rock structures formed by tectonic forces.

Stress

The magnitude of force applied per unit area to a rock body.

Strain

The resulting deformation, distortion, or change in size and shape of a rock body caused by applied stress.

Elastic Deformation

A reversible type of deformation where a rock deforms under stress but recovers its original shape once the applied stress is removed.

Brittle Deformation

Permanent deformation where rock fractures, breaks, or faults under stress, typically at shallow depths and low temperatures.

Ductile Deformation

Permanent deformation where rock bends, flows, or folds without breaking, typically occurring at elevated temperatures and confining pressures.

Contour Interval

The specific vertical difference in elevation between adjacent contour lines on a topographic map.

Strike

The compass bearing of a horizontal line formed by the intersection of an inclined planar rock surface with a horizontal reference plane.

Dip

The angle of maximum tilt of an inclined rock layer measured downward from the horizontal plane, oriented perpendicular to the strike.

Anticline

An up-arched rock fold formed by compressional stress in which the oldest rock layers occupy the central core of the structure.

Syncline

A down-warped trough fold formed by compressional stress in which the youngest rock layers occupy the central core of the structure.

Plunging Fold

A fold whose hinge line or axis is inclined relative to the horizontal plane rather than running horizontally.

Geologic Dome

A three-dimensional upward crustal upwarping analogous to a circular anticline, where rock layers dip radially outward and the oldest rocks are in the center.

Geologic Basin

A three-dimensional bowl-shaped downwarping analogous to a circular syncline, where rock layers dip inward and the youngest rocks are at the center.

Joint

A fracture or crack in a rock along which no significant displacement or motion has taken place.

Fault

A fracture in rock along which there has been observable displacement and movement of the opposing blocks.

Dip-slip Fault

A fault where displacement occurs predominantly parallel to the dip direction of the fault plane, moving vertically up or down.

Strike-slip Fault

A fault formed under shearing stress where displacement is predominantly horizontal, parallel to the strike of the fault plane.

Normal Fault

A dip-slip fault produced by tensional stress in which the hanging wall block slides downward relative to the footwall block.

Reverse Fault

A dip-slip fault produced by compressional stress in which the hanging wall block moves upward relative to the footwall block.

Horsts and Grabens

Structural crustal blocks bounded by normal faults under tensional stress, where horsts represent uplifted blocks and grabens represent downdropped fault blocks.

Viscosity

A physical fluid property representing internal resistance to flow; silica-rich, cooler magmas possess high viscosity, whereas hotter, silica-poor magmas have low viscosity.

Mafic Magma

A hot, low-viscosity, silica-poor magma that typically drives non-explosive, effusive volcanic eruptions.

Felsic Magma

A cooler, high-viscosity magma containing the highest silica content, responsible for violent and explosive volcanic eruptions.

Effusive Eruption

A relatively non-violent volcanic eruption dominated by the calm outpouring of fluid, low-viscosity lava flows.

Explosive Eruption

A violent volcanic eruption driven by the expansion of trapped gases inside highly viscous, silica-rich magma.

Pyroclastic Flow

A rapidly moving, extremely hot, and lethal avalanche of incandescent gas, ash, and volcanic rock fragments traveling down a volcano's slopes.

Lahar

A destructive volcanic mudflow or debris flow generated when volcanic debris and ash mix with water from rain or melted snow and ice.

Tephra

All fragmented rock material ejected into the air by an explosive volcanic eruption regardless of size.

Pahoehoe Lava

A basaltic lava flow characterized by a smooth, billowy, or ropey surface texture formed from fluid lava.

Aa Lava

A basaltic lava flow characterized by a rough, jagged, and blocky surface texture formed as cooling lava fragments.

Shield Volcano

A massive, broad, and gently-sloping volcano built by successive layers of low-viscosity basaltic lava erupted effusively.

Stratovolcano (Composite Cone)

A large, steep-sided volcano constructed of alternating layers of intermediate-to-felsic lava flows, volcanic ash, and pyroclastic debris.

Cinder Cone

A small, steep-sided volcano formed by the rapid accumulation of loose pyroclastic fragments (cinders) around a single volcanic vent.

Volcanic Dome

A steep-sided, rounded mound formed when highly viscous, silica-rich felsic lava slowly oozes out and plugs a volcanic vent.