Plate Tectonics

convergent boundary

A tectonic plate boundary where two plates collide, come together, or crash into each other.

Pangaea

According to Wegener, the continents drifted together to form one landmass called Pangaea

The geological theory that states that pieces of Earth's crust are in constant, slow motion is called

continental drift

The process that powers plate tectonics is

convection

Wegener's theory that continents slowly moved over the Earth's surface became known as

drifting continents

A device that scientists use to map the ocean floor is

sonar

The transfer of heat by the direct contact of particles of matter is

conduction

The process that continually adds new material to the ocean floor is called

sea floor spreading

The single landmass that broke apart 250 million years ago was called Pangea

true

What are 3 kinds of evidence scientists have found to support ocean floor spreading?

1. Evidence from Molten Material The evidence from molten material was strange rocks shaped like pillows or like toothpaste squeezed from a tube. Such rocks form only when molten material hardens quickly after erupting under water. These rocks showed that molten material has erupted again and again along the mid-ocean ridge. 2. Evidence from Magnetic strips Scientists discovered that the rock that makes up the ocean floor lies in a pattern of magnitized strips the stripes hold a record of reversals in Earths magnetic field the rock material is cooled and hardned as the rock cooled the iron bits in side linded up in the direction of Earths magnetic poles using sencitive instreaments scientists recorded magnetic memory on both sides of the ridge they found that the strips on the rock that formed when earths magnetic field formed alternated with strips of rock that pointed south. 3. Evidence from drilling samples samples from the sea floor were brought up and scientists learned that the rocks farther away from the mid ocean ridge were the oldest and the ones closest were always the newest. This showed that sea floor spreading had actually taken place.

Explain Sea-Floor Spreading

1. Molten material erupts through the mid-ocean ridge. 2. The molten material hardens to form the rock of the ocean floor. 3. The older rock moves outward on both sides of the ridge.

**Convection current & what causes them?

A convection current is the flow that transfers heat within a fluid. Convection currents are caused by the combination of heating and cooling the fluid, changes in the fluid's density, and the force of gravity. Eg. heating soup on the stove. 1. Soup at bottom of the pot gets hot, expands, and becomes less dense. 2. The warm, less dense soup moves to the top of the pot over the cooler, denser soup. 3. Soup on top cools, gravity pulls it back down to the bottom of the pot where it's heated again. 4. This causes a constant flow of warm soup rising to the top of pot, and cooler denser soup goes to the bottom of pot. 5. Convection currents continue as long as heat is added. Without heat, convection currents will stop.

rift valley

A deep valley

**Granite

A rock that is usually light colored, igneous, has a coarse texture, and is found in the continental crust.

Continental drift

Alfred Wegener's idea that the continents slowly moved over earth's surface

The relatively soft layer of the mantle is the

Asthenosphere

**Compare and contrast the Asthenosphere with the Lithosphere

Asthenosphere: sits below the lithosphere. Is hotter, & under more pressure causing it to be less rigid than the lithosphere. The Asthenosphere is somewhat soft, and the Lithosphere is rigid like the crust. In Greek, Asthenosphere means "weak", and Lithosphere means "stone."

Describe the type of movement that occurs at each type of plate boundary.

At a divergent boundary two of Earths plates slide apart. At a converging boundary is when two plates come together and converge. At a transform boundary two plates slip past each other moving in opposite directions.

Compare and contrast the asthenosphere with the lithosphere.

Both: part of the mantle, are solid, Difference: Asthenosphere: softer/more flexible, thicker, hotter; Litho: rigid, outer part of the mantle, thinner, cooler

**Conduction

Conduction is the transfer of heat through a material, or between materials that are touching. Eg. A kettle of boiling water. The heated particles move from the kettle to the water, heating it up.

What are convection currents and what causes them?

Convection currents are the flow that transfers heat within a fluid.

**What causes convection currents in Earth's mantle?

Convection currents in Earth's mantle are caused by heat from the core and the mantle itself. The great heat and pressure in the mantle rock rise slowly from the bottom of the mantle toward the top. The hot rock eventually cools and sinks back through the mantle. This cycle of rising and sinking takes place over, and over.

Label the layers of Earth in order.

Crust, Mantle, Outer Core, Inner Core

**Density

Density is the measure of how much mass there is in a volume of a substance. eg. rock is denser than water because a given volume of rock has more mass than the same volume of water.

Direct evidence

Evidence from rocks collected by drilling into Earth

When two continental plates diverge a transform boundary forms.

False divergent boundary

The transfer of heat through space is called convection true or false

False radiation

**True/False? Radiation is the transfer of heat by the movement of a heated fluid

False. Convection currents transfer heat by the movement of heated fluid

**True/False? Density is a measure of how much heat there is in a volume of a substance

False. Density is the measure of how much mass there is in a volume of a substance.

How is the evidence from rock samples used to learn about earths interior?

Geologist's drill holes deep into the earth and bring up samples of rock. They use the rocks to make inferences about conditions deep inside earth.

How is the indirect evidence from seismic waves used to learn about the earths interior?

Geologists record the waves and study how they travel through Earth. The speed of the seismic waves and the paths they take reveal the structure of the planet.

**What are 2 types of evidence geologists use to learn about Earth's interior?

Geologists use direct evidence from rock samples, and indirect evidence from seismic waves to learn about the Earth's interior.

According to Wegener, how do mountains form?

He proposed that when continents collide, their edges crumple and fold. The folding action pushed up huge mountains.

**The movement of energy from a warmer object to a cooler object is called?

Heat Transfer

What causes convection currents in the Earth's mantle

Heat from the core and mantle.

Sea-Floor Spreading

In Sea-Floor-Spreading, the sea-floor spreads apart along both sides of a mid-ocean ridge as new crust is added to the ocean floor. As a result, the ocean floors move like conveyor belts carrying the continents along with them

Where does sea-floor spreading begin?

It begins at a mid-ocean ridge

Subduction of the ocean floor takes place at

Mid-ocean ridges

All the continents were once joined together in a super continent called

Pangea

What are plates

Plates are a section of the lithosphere that slowly moves over the asthenosphere carrying peices of continental and oceanic crust.

**Pressure

Pressure is the result from a force pressing on an area. Because of the weight of the rock above, pressure inside Earth increases as you go deeper.

**The transfer of energy through empty space is called?

Radiation

**Radiation

Radiation is the transfer of energy through space. Heat transfer by radiation takes place with no direct contact between a heat source and an object. Eg. The heat you feel from getting into a pool heated by the sun's rays.

What are two types of evidence geologists use to learn about Earth's interior?

The Types of evidence they use are indirect evidence from seismic waves and direct evidence from rock samples.

**Basalt

The crust beneath the ocean is called oceanic crust.A dark, dense, igneous rock with a fine texture, found in oceanic crust.

**Crust: What do you find on the crust?

The crust is the layer of rock that forms the Earth's outer skin. The crust is the layer of solid rock that includes both dry land & the ocean floor. You'll find rocks & mountains, soil & water on the crust.

**List Earth's 3 main layers

The crust, mantle, & core

**What are the 4 layers of the Earth's Interior?

The crust, the mantle, the outer core, & the inner core. These layers vary greatly in size, composition, temperature, & pressure.

Where would you expect to find the oldest rock on the sea floor.

The farthest away from a mid-ocean ridge.

In which layer are the Lithosphere & Asthenosphere found

They are found in the Mantle

**Mantle

The layer of hot rock between the crust and the core. The mantle is nearly 3,000km thick.

What happens to oceanic crust at a deep ocean trench

The oceanic crust sinks into the deep ocean trench.

subduction

The process by which ocean floor sinks beneath a deep-ocean trench and back into the mantle.

What are the three types of plate boundaries

The three types of plate boundaries are Divergent boundaries convergent boundaries and transform boundaries.

**Convection

The transfer of heat by the movement of fluids (liquid or gases). During convection, heated particles begin to flow, and this flow transfers heat from one part of the fluid to another. Eg. A pot of boiling water

How do rocks along the central valley of the mid-ocean ridge provide evidence of sea floor spreading.

They provide evidence of seafloor spreading because the oldest rocks are the farthest away and the newer ones are the closest so they are the new floor pushing away the old rocks.

What do scientists think causes movement in the Earth's plates

They think that convection currents cause movement in the Earth's plates.

Breaks in Earth's crust where rocks have slipped past each other are called

Transform boundaries

**Seismic waves

Vibrations that travel through Earth carrying the energy released during an earthquake

two plates collide with each other at

a convergent boundary

Fault

a crack in the earth's crust

andesite

a dark gray volcanic rock

deep-ocean trench

a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle

What is a deep ocean trench

a deep valley along the ocean floor where oceanic crust slowly sinks toward the mantle; a convergent boundary

**Inner core

a dense ball of solid iron and nickel at the center of Earth. The dense ball is caused by extreme pressure.

sonar

a device that determines the distance of an object under water by recording echoes of sound waves

**Outer core

a layer of molten (liquid) iron and nickel that surrounds the inner core of Earth

Divergent boundary

a plate boundary where two plates move away from each other

Transform boundary

a plate boundary where two plates move past each other in opposite directions

**Lithosphere

a rigid layer made up of the uppermost part of the mantle and the crust.

Plate

a rigid layer of the Earth's crust that is believed to drift slowly

Fossil

a trace of an ancient organism that has been preserved in rock

scientific theory

a well-tested concept that explains a wide range of observations

Mid-ocean ridge

an undersea mountain chain where new ocean floor is produced; a divergent plate boundary

Slow movements of mantle rock called radiation transfer heat in the mantle

false

Mid-ocean ridges are places where oceanic crust sinks back to the mantle

false deep ocean trenches

Density is a measure of how much heat there is in a volume of a substance

false mass

A is any trace of an ancient organism preserved in rock.

fossil

Indirect evidence

from seismic waves

A chain of Underwater mountains along which sea-floor spreading occurs is a

mid-ocean ridge

A is a deep valley on land that forms along a divergent boundary

rift valley

The process by which the ocean floor sinks into the mantle is called

subduction

**Asthenosphere

the soft layer of the mantle on which the lithosphere sits.

In your own words what is the theory of plate tectonics

the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle

Plate tectonics

the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle

A scientific is a well-tested concept that explains a wide range of observations

theory

**True/False: Conduction is heat transfer by the direct contact of particles of matter.

true

Continental crust is made of rocks such as granite true or false

true