Chapter 8

List three pieces of evidence supporting plate movement:

* Fossil Distribution * Coastline Matching * Paleomagnetism

Describe divergent boundaries:

Linear features that exists between two tectonic plates that are moving away from each other.

Describe transform plate boundaries:

Places where plates slide sideways past each other. At transform boundaries lithosphere is neither created nor destroyed. Many transform boundaries are found on the sea floor, where they connect segments of diverging mid-ocean ridges. California's San Andreas fault is a transform boundary.

What is a fault?

A break in the rocks that make up the Earth's crust, along which rocks on either side have moved past each other.

What are earthquakes?

A sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action.

Compare these different types of volcanoes: Active volcanoes, Dormant volcanoes, Extinct volcanoes

Active Volcanoes: Volcanoes that has had at least one eruption during the past 10,000 years. An active volcano might be erupting or dormant. Dormant Volcanoes: Active volcanos that are not erupting, but supposed to erupt again. Extinct Volcanoes: Volcanoes that have not had an eruption for at least 10,000 years and is not expected to erupt again in a comparable time scale of the future.

Describe each of these layers: Core, Inner Core, and Outer Core

Core: The core is mostly iron metal. The core makes up about 31% of the Earth. Inner Core: The Earth's inner core is made up of iron and nickel, just like the outer core, however, the inner core is different. The inner core is so deep within the earth that it's under immense pressure. So much pressure that, even though it is so hot, it is solid. The inner core is the hottest part of the Earth, and, at over 5000 degrees C, is about as hot as the surface of the sun Outer Core: The Earth's outer core is made up of iron and nickel and is very hot (4400 to 5000+ degrees C). This is so hot that the iron and nickel metals are liquid! The outer core is very important to earth as it creates something called a magnetic field. The magnetic field the outer core creates goes way out in to space and makes a protective barrier around the earth that shields us from the sun's damaging solar wind.

What are volcanoes?

Mountains or hills, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust.

Compare the Oceanic Crust to the continental crust:

Oceanic Crust: Part of the Earth's crust that covers the ocean basins. It consists of dark-colored rocks made up of basalt. This rock is made up of silicon, oxygen, and magnesium. Continental Crust: Accounts for 40% of the surface of the Earth. It is made up of granite rock which is light in color. This rock is rich in constituents like silicon, aluminum, and oxygen.

Describe convergent plate boundaries:

Tectonic boundaries where two plates are moving toward each other. If the two plates are of equal density, they usually push up against each other, forming a mountain chain. If they are of unequal density, one plate usually sinks beneath the other in a subduction zone.

Why do tectonic plates move?

Tectonic plates move because they are floating on top of the liquid mantle. The mantle itself moves due to convection currents: hot rock rises, gives off some heat, then falls. This creates vast swirls of moving liquid rock under the crust of the earth, which jostles the plates of crust on top.

How is earth's magnetic field created by the core?

The Earth's magnetic field is believed to be generated by electric currents in the conductive material of its core, created by convection currents due to heat escaping from the core.

How are earthquakes measured?

The magnitude of an earthquake, usually expressed by the Richter Scale, is a measure of the amplitude of the seismic waves. The moment magnitude of an earthquake is a measure of the amount of energy released - an amount that can be estimated from seismograph readings.

Describe the mantle:

The mantle extends to a depth of approximately 1,800 miles (2897km), and is made of a thick, solid, rocky substance that represents about 85% of the total weight and mass of the Earth.

Define subduction zone:

The place where two lithospheric plates come together, one riding over the other. Most volcanoes on land occur parallel to and inland from the boundary between the two plates.

Define Lithosphere:

The rigid outer part of the earth, consisting of the crust and upper mantle.

Define asthenosphere:

The upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur.