Chapter 17 Plate Tectonics Quiz (Earth Science)

Magnetometer

A device that can detect small changes in magnetic fields-detect fields caused by ocean rocks

Isochron

An imaginary line on a map that shows points that have the same age.

Types of Convergent Boundaries

Continental-Continental: Form when two continental plates collide (this happens after an oceanic plate has converged with a continental plate) This form a vast mountain range. Oceanic-Oceanic: Subduction zone is formed when one plate descends below the other which create a trench and volcanic island that parallel to the trench. Oceanic-Continental: The oceanic plate descend below the continental plate and produces a trench and volcanic arc.

Tectonic plate

Huge pieces of crust and rigid upper mantle that fit together at their edges to cover Earth's surface.

Sonar

Measures water depth and map topography of ocean floor

Deep sea trenches

Narrow, elongated depression in the sea floor

Magnetic symmetry

Regions of normal and reverse polarity from stripes across the ocean floor parallel to the ocean ridges. The ages and width of the stripes match from one side of the ridges to the other.

Divergent Boundary

Regions where two tectonic plates are moving apart from each other. *Most divergent boundaries are found along the seafloor in RIFT VALLEY. *Characteristic: The formation of new crust, high hear flow, volcanism, and Earth quakes.

Using the data from the discoveries of the ocean rocks, sediments and magnetic field records, sea floor spreading was proposed.

Sea floor spreading is the theory that explains how new oceanic crust is formed at ocean ridges and destroyed in at deep sea trenches.

Slab pull

The tectonic process associated with convection currents in Earth's mantle that occurs as the weight of the subducting plate pulls the trailing lithosphere into a subduction zone.

Ridge push

The tectonic process associated with convection currents in Earth's mantle that occurs when the weight of an elevated ridge pushes an oceanic plate toward a subduction zone.

Plate tectonic

The theory that describes how tectonic plates move and shape Earth's surface. (Move in different directions and rates)

Convergent Boundary

Two tectonic plates move toward each others. *When two plates collide, the denser plate eventually descends below the other, less dense plate in a process called subduction.

What are common along the mid-ocean ridges?

Volcanoes and earthquakes

Continental Drift

Wegener's idea which proposed that Earth's continents had once been joined as a single landmass that broke apart and sent the continents adrift.

Magnetic reversal

When the flow in the outer core changes and magnetic field changes direction

Lines of evidence that led Wegener to suggest that Earth's continents have moved.

a. Evidence from rock formation: Layers of rocks are identical in other continents. b. Evidence from Fossils: Similar fossils of several different species have been found in different continents. c. Climate evidence: 1. different between where plants lived and where fossils were found. 2. Coal deposit (Found in Antarctica. Coal is formed from decomposing/compacted swamp plants. 3.Glacial deposits-found in Africa, India, South America. (Weird)

When lava solidifies, iron-rich minerals form and as they crystallize they

act like tiny compasses and align with Earth's magnetic fields

Earth has a magnetic field that is generated

by the flow of molten iron in the outer core.

The rising material in a convection current spreads out as it reaches the upper mantle and

causes both upward and sideways forces, which lift and split the lithosphere at divergent plate boundaries.

The downward part of a convection current occurs where a sinking force

pulls tectonic plates downward at convergent boundaries

Paleomagnetism

the Study of the history of Earth's magnetic fields.

Convection

the transfer of thermal energy by the movement of heated material from one place to another. *The mechanism that drives the movement of tectonic plates.

Convection in the mantle

which moves the crust and out-most part of of the mantle and transferring thermal energy from Earth's interior to its exterior.

Pangea

"All the Earth" *The super continent that was once adjoined. (Happen 200 million years ago)

Why continental drift was not accepted when it was first proposed?

1. Did not explain what pushed the land masses so far. 2. How were continents moving across solid crust/mantle?

Discoveries of ocean rocks and sediments

1. Rock ages vary and predictable (Younger near ridge, and older if it moves away) 2. Ocean sediments are a few hundred meters thick, on continents 20 km thick.