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Geology 1100
Exam 1 Flashcards
48
Geology
Undergraduate 2
09/16/2010

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Term
Pangaea
Definition
The vast supercontinent that eventually drifted apart to slowly to create the current earth
Term
Continental Drift
Definition
The process of Pangaea breaking apart to form the current earth.
Term
Sea-Floor Spreading
Definition
Hess and Dietz proposed that as continents drift apart, a new ocean floor forms between them by a process described as S-FS. They suggested continents move toward each other when the old ocean floor between them sinks back down into the earth
Term
Subduction
Definition
The process of the ocean floor sinking back down into the sea-floor.
Term
Plates
Definition
20 Distinct pieces that move relative to each other under the earth.
Term
Plate Tectonics
Definition

Because there is a confirmed model of plate movement, this theory is called plate tectonics

Geologists view this as the grand unifying theory of geology, because it can successfully explain a great many geologic phenomena

Term
Wagner's Evidence for Continental Drift
Definition

The Fit of the Continents

Locations of Past Glaciations

The Distribution of Climatic Belts

The Distribution of Fossils

Matching Geologic Units

Term
Paleomagnetism
Definition
A record of the Earth's magnetic field in the past
Term
Magnetic Dipole
Definition
The earth's magnetic field is represented by this
Term
Magnetic Poles
Definition
The dipole intersects the earth at two points, known as the magnetic poles
Term
Magnetic Declination
Definition
The between the direction that a compass needle points and a line of longitude
Term
Magnetic Inclination
Definition
Angle between a magnetic field line and the surface of the earth at a given location
Term
Paleopole
Definition
The supposed position of the Earth's magnetic north pole in the past
Term
Apparent Polar-Wander Path
Definition

Successive positions of dated paleopoles on a map. These trace out a curving line.

EACH CONTINENT HAS A DIFFERENT APPARENT POLAR-WANDER PATH

Term
Bathymetry
Definition
Depth Variations
Term
Abyssal Plains
Definition
Broad, relatively flat regions of the ocean that lie at a depth of about 4-5 km below sea level
Term
Mid-Ocean Ridges
Definition
Elongated submarine mountain ranges whose peaks lie only about 2 to 2.5 km below sea level
Term
Trenches
Definition
Deep throughs that reach about 8-12 km of depth
Term
Volcanic Arcs
Definition
Curving chains of active volcanoes
Term
Seamounts
Definition
Isolated submarine mountains, which were volcanoes but no longer erupt
Term
Fracture Zones
Definition
Surveys reveal that the ocean floor is diced up by narrow bands of vertical cracks and broken-up rock. These lie roughly at right angles to mid-ocean ridges, effectively segmenting the ridges into small pieces.
Term
Magnetic Anomaly
Definition
Difference between the expected strength of the Earth's main dipole field at a certain location and the ACTUAL measured strength of the magnetic field at that location
Term
Marine Magnetic Anomalies
Definition
Distinct alternating bands due to magnetic reversals. Look like a candy cane if positive and negative were colored
Term
Magnetic Reversals
Definition
Times when the Earth's magnetic field flips from normal to reverse polarity and vice versa
Term
Magnetic-reversal Chronology
Definition
The history of magnetic reversals
Term
Lithosphere
Definition
Consists of the Crust and Top layer of the Upper Mantle. It is rigid, when a force pushes it, it breaks or bends
Term
Asthenosphere
Definition
Under the lithosphere, relative soft plastic toothpaste later composed of warmer mantle that can flow when acted on by force
Term
Lithosphere Plates
Definition
The plates of the earth
Term
Plate Boundaries
Definition
The breaks between the plates
Term
Active Margins
Definition
Plate boundaries
Term
Passive Margins
Definition
Not plate boundaries
Term
Plate Movement
Definition
Occurs at a rate of 1cm to 15 cm a year
Term
Divergent Boundaries
Definition
A boundary at which two plates move away from each other
Term
Convergent Boundaries
Definition
A boundary at which two plates move toward each other and one plate sinks beneath the other
Term
Transform Boundaries
Definition

Boundaries that move along side one another.

No new plate forms and no old plate is consumed.

Term
Black Smokers
Definition
Chimneys that spew hot, mineralized water that rose through cracks in the sea floor, after being heated by magma below the surface. The color comes from a suspension of tiny mineral grains that precipitate in the water a the water cools
Term
Wadati-Benioff Zone
Definition
The belt of earthquakes in a downgoing plate
Term
Triple Junctions
Definition
Places where three plate boundaries intersect
Term
Hot Spots
Definition
Volcanoes that exist at isolated points and are not a consequence of movement of a plate boundary.
Term
Mantle Plume
Definition
Column of very hot rock rising up through the mantle to the base of the lithosphere
Term
Hot-Spot Track
Definition
Chain of extinct volcanoes
Term
Rifting
Definition
Divergent boundaries form when a continent splits and separates into two continents
Term
Continental Rift
Definition
Linear Belt in which the continental lithosphere undergoes rifting
Term
Collision
Definition
When a piece of buoyant lithosphere such as a continent or island arc moves into the subduction zone
Term
Ridge-Push Force
Definition
Develops because mid-ocean ridges lie at a higher elevation than the adjacent abyssal plains of the ocean
Term
Slab-Pull Force
Definition
The force that subducting, downgoing plates apply to oceanic lithosphere at a convergent margin
Term
Relative Plate Velocity
Definition
The movement of plate A with respect to plate B
Term
Absolute Plate Velocity
Definition
Movement of both plates relative to a fixed point in the mantle
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