Science Unit 2 Julianne 9th grade
Terms
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- CONTINENTAL DRIFT
- hypothesis stating that the continents once formed a single landmass, broke up and drifted to their present locations.
- PANGAEA
- Single landmass thought to have been the origin of all continents.
- PANTHALASSA
- Giant ocean surrounding Pangaea.
- MID-ATLANTIC RIDGE
- Undersea mountain range with a steep, narrow valley along its center.
- MID-OCEAN RIDGE
- System of undersea mountain ranges that wid around the earth.
- SEAFLOOR SPREADING
- Movement of the ocean floor away from either side of a mid-ocean ridge.
- PLATE TECTONICS
- Theory that the lithosphere is made up of plates that float on the asthenosphere and that the plates posibly are moved by convection currents.
- CONTINENTAL CRUST
- Material that makes up landmasses.
- LITHOSPHERE
- Thin outer shell of the earth consisting of the crust and the rigid upper mantle.
- ASTHENOSPHERE
- Zone of mantle beneath the lithosphere that consists of slowly flowing solid rock.
- DIVERGENT BOUNDARY
- Boundary formed by two lithospheric plates that are moving apart.
- RIFT VALLEY
- Steep, narrow valley formed as lithospheric plates separate.
- CONVERGENT BOUNDARY
-
Border formed by the direct collision of two lithospheric
plates - SUBDUCTION ZONE
- Region where one lithospheric plate moves under another.
- OCEAN TRENCH
- Deep valley in the ocean floor that forms along a subduction zone.
- ISLAND ARC
- A chain of volcanic islands formed when part of the subducted plate melts and the resulting molten rock rises to the surface along the trench
- TRANSFORM FAULT BOUNDARY
- Boundary formed where two lithospheric plates slide past each other
- CONVECTION CURRENT
- Movement in a fluid caused by uneven heating.
- THEORY OF SUSPECT TERRANES
- Theory that continents are a patchwork of pieces of land that have individual geologic histories.
- TERRANES
- Pieces of land with a geologic history distinct from that of the surrounding land.
- DEFORMATION
- Bending, tilting, and breaking of the earth's crust.
- ISOSTASY
- Balancing of the forces pressing up and down on the earth's crust.
- ISOSTATIC ADJUSTMENTS
- Up-and-down movements of the earth's crust to reach isostasy.
- STRESS
- Force that causes pressure in rocks of the earth's crust.
- STRAIN
- Change in shape and volume of rocks that occurs due to stress.
- COMPRESSION
- Stress that squeezes crustal rocks together.
- TENSION
- Stress that pulls rocks apart.
- SHEARING
- Stress that pushes rocks in opposite horizontal directions.
- FOLDING
- Permanent deformation or bending of a rock under stress.
- ANTICLINE
- Upcurved fold in horizontal rock layers.
- SYNCLINE
- Downcurved fold in horizontal rock layers.
- MONOCLINE
- Gently dipping bend in horizontal rock layers.
- FRACTURE
- Break in rock along which there is no movement.
- FAULT
- Break in rock along which rocks on either side of the break move.
- NORMAL FAULT
- Fault in which the hanging wall moves down relative to the footwall.
- FAULT PLANE
- Surface of a fault along which movement of rocks occurs.
- HANGING WALL
- Rock above a normal fault plane.
- FOOTWALL
- Rock below a fault plane.
- REVERSE FAULT
- Fault in which the hanging wall moves up relative to the footwall.
- THRUST FAULT
- Type of reverse fault in which the fault plane is nearly horizontal rathe4r than vertical.
- STRIKE-SLIP FAULT
- Fault in which the rock on either side of a fault plane slides horizontally.
- MOUNTAIN RANGE
- Group of adjacent mountains wiht the same general shape and structure.
- MOUNTAIN SYSTEM
- Group of adjacent mountain ranges.
- MOUNTAIN BELTS
- Group of large mountain systems.
- FOLDED MOUNTAIN
- Landform created when tectonic movements bend and uplift rock layers.
- PLATEAUS
- Large area of flat-topped rocks high above sea level.
- FAULT-BLOCK MOUNTAINS
- Mountain formed where faulting breaks the earth's crust into large blocks and the blocks are uplifted and tilted.
- GRABEN
- Long, narrow valley formed by faulting and downward slippage of a crustal block.
- VOLCANIC MOUNTAIN
- mountain formed when molten rock erupts onto the earth's surface.
- DOME MOUNTAIN
- Landform created when molten rock pushes up rock layers on the earth's surface and the layers then are worn away in places, leaving
- EARTHQUAKE
- Vibration of the earth's crust.
- ELASTIC REBOUND THEORY
- Theory that rocks that are strained past a certain point will fracture and spring back to their original shape.
- AFTERSHOCK
- tremor that follows and is smaller than a major earthquake.
- FOCUS
- Area along a fault at which slippage first occurs, initiating an earthquake.
- EPICENTER
- Point on the earth's surface directly above the focus of an earthquake.
- PACIFIC RING OF FIRE
- Major earthquake zone that forms a ring around the Pacific Ocean.
- FAULT ZONE
- Group of interconnected faults.
- P-WAVE
- Primay wave; the fastest wave generated by an earthquake and the first to be recorded by a seismograph.
- S-WAVE
- Secondary wave; a wave generated by an earthquake and the second to be recorded by a seismograph.
- L-WAVE
- Surface or long wave; the slowest wave generated by an earthquake and the last to be recorded by a seismograph.
- SEISMOGRAPH
- Instrument used to detect and record seismic waves.
- MICROQUAKE
- Earthquake with a magnitude less than 2.5 on the Richter scale.
- MERCALLI SCALE
- Scale that expresses the intensity of an earthquake with a Roman numeral and a description.
- INTENSITY
- Amount of damage caused by an earthquake.
- TSUNAMI
- Giant ocean wave tht often occurs after a major earthquake with an epicenter on the ocean floor.
- VOLCANO
- Lava and tephra built up on the earth's sufrace around a vent.
- LAVA
- Magma that reaches the earth's surface.
- VOLCANISM
- An activity that includes the movement of magma toward or onto the earth's surface.
- SEISMIC GAP
- Zone of rock in which a fault is locked and unable to move and in which no major earthquake has occurred for at least 30 years.
- MAGMA
- Liquid rock produced deep inside the earth.
- FISSURE
- Crack in a rock surface through which lava flows.
- HOT SPOT
- Area of volcanism within a lithospheric plate.
- MAFIC LAVA
- Dark-colored lava rich in magnesium and iron.
- FELSIC LAVA
- Silica-rich lava.
- PAHOEHOE
- solidified mafic lava with a wrinkled surface.
- AA
- Jagged chunks of lava formed by rapid cooling on the surface of a lava flow.
- PILLOW LAVA
- Lava that flows our of fissures on the ocean floor and cools rapidly in rounded shapes.
- TEPHRA
- Also called pyroclastic material, all the rock fragments ejected from a volcano.
- PYROCLASTIC MATERIAL
- Also called tephra, all of the rock fragments ejectged from a volcano.
- VOLCANIC ASH
- Tephra particles between 0.25 and 2 mm in diameter.
- VOLCANIC DUST
- Tephra particles less than0.25 mm in diameter.
- VOLCANIC BOMB
- Large spindle-shaped clot of lava thrown out of a volcano.
- VOLCANIC BLOCK
- The largest tephra, formed from solid rock blasted from a fissure.
- SHIELD CONE
- Volcanic deposit of hardened lava with a broad base and gentle slopes.
- CINDER CONE
- Steep-sloped deposit of solid fragments ejected from a volcano.
- COMPOSITE CONE
- Also called stratovolcano, steep-sloped volcanic deposit with alternating layers of hardened lava flows and tephra.
- STRATOVOLCANOES
- Also called a composite cone, steep-sloped volcanic deposit with alternating layers of hardened lava flows and tephra.
- CRATER
- Funnel-shaped pit at the top of a volcanic cone.
- CALDERA
- Large basin-shaped depressionformed when an explosion destroys the upper part of a volcanic cone.