chapter 17 study guide

Mid-Atlantic Ridge is an example of?

Mid-Atlantic ridge is convergent boundaries.

Plate tectonics

States that Earth's crust and rigid upper mantle are broken into enormous slabs called plates.

List two major flaws of Wegener's theory.

1. He could not satisfactorily explain what was causing the continents to move. 2. He also proposed that the continents were plowing through a stationary ocean floor.

Pangaea

Ancient land mass made up of all the continents that began to break apart about 200 million years ago.

seafloor spreading

Hess's theory that new ocean crust is formed at mid-ocean ridges and destroyed at deep-sea trenches; occurs in a continuous cycle of magma intrusion and spreading.

rift valley

Long narrow depression that forms when continental crust begins to separate at a divergent boundary.

Deep-sea trench

Long, relatively narrow depression in the seafloor that can extend for thousands of kilometers, is the deepest part of the ocean basin, and is found primarily in the Pacific Ocean.

Boundaries

Man-made or naturally created lines dividing parts of the earth's surface (i.e. political units, coast lines)

divergent boundaries

Place where two of earth's tectonic plates are moving apart; is associated with volcanism, earthquakes, and high heat flow, and is found primarily on the seafloor.

convergent boundary

Place where two of earth's tectonic plates are moving toward each other, is associated with trenches, islands arcs, and folded mountains.

transform boundaries

Place where two tectonic plates slide horizontally past each another that is characterized by long faults and shallow earthquakes.

Where are most divergent boundaries found?

Primarily on the seafloor,is where divergent boundaries are found.

subduction

Process by which one tectonic plate slips beneath another tectonic plate.

theory of plate tectonics

States that earth's crust and upper mantle are broken into plates, which are huge rock slabs that move in different directions and at different rates over earth's surface.

paleomagnetism

Study of earth's magnetic record using data gathered from iron-bearing minerals in rocks that have recorded the orientation of earth's magnetic field at the time of their formation.

What is the best know transform boundary?

The best know trans form boundary is where two tectonic plates slide horizontally past each another.

List three types of data that Wegener used to support his hypothesis.

Three types of data that wegener used to support his hypothesis is

convection

Transfer of energy by the flow of a heated substance.

continental drift

Wegner's hypothesis that earth's continents were joined as a single land mass, called Pangaea, that broke apart about 200 million years ago and slowly moved to their present positions.

Two important topographic features of the ocean floor are:

rough and irregular with high mountains and deep impressions.

Ocean Ridges

the undersea mountain chains that are formed when magma oozes up and solidifies between tectonic plates that are moving apart.