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Chapter 7

Name the 3 layers of the Earth:

1. CRUST
2. MANTLE
3. CORE

Composition of the Earth:

The lightest materials make up the outermost layer, and the densest materials make up the inner layers. This is because lighter materials tend to float up, while heavier materials sink

CRUST:

Outermost layer of the Earth

The CRUST is how thick?

5-100 km thick

Name the two types of crust:

1. CONTINENTAL CRUST
2. OCEANIC CRUST

The CONTINENTAL CRUST composition:

has a composition similar to granite and an average depth of 30 km thick.

The OCEANIC CRUST composition:

has a composition similar to basalt and is 5-8 km thick, but is denser than the continental crust.

MANTLE:

The layer between the Crust and Core. The Mantle is thicker than the crust and contains most of Earth's mass.

CORE:

Extends from the bottom of the Mantle to the center of the Earth. Geologist believe the Core is made mostly of iron.

Name the 5 main physical layers of the Earth:

1. LITHOSPHERE
2. ASTHENOSPHERE
3. MESOSPHERE
4. OUTER CORE
5. INNER CORE

LITHOSPHERE is :

The outermost rigid layer of the Earth. It is made up of two parts, the crust and the rigid upper part of the mantle. The lithosphere is divided into pieces called TECTONIC PLATES.

ASTHENOSPHERE is:

A soft layer of the mantle on which pieces of the lithosphere move. It is made of solid rock that, like putty, flows slowly (as fast as your fingernails grow). It is known as the "weak sphere".

MESOSPHERE is:

Beneath the Asthenosphere and is the strong lower part of the mantle. It extends down to the Earth's core and is known as the "middle sphere".

OUTER CORE is:

The liquid layer of the Earth's core that lies beneath the mantle and surrounds the inner core.

INNER CORE is:

The solid, dense center of our planet that extends from the bottom of the outer core to the center of the Earth.

TECTONIC PLATES are:

Pieces of the lithosphere that move around on top of the Asthenosphere

How many major TECTONIC PLATES are there?

10 - The Pacific Plate, North American Plate, Cocos Plate, Nazca Plate, South American plate, African Plate, Eurasian Plate, Indian Plate, Australian Plate and Antarctic Plate

Tectonic plates can be made up entirely of continental crust, or entirely of oceanic crust, or of both continental and oceanic crust. True or False?

True

Tectonic plates are all roughly the same size. True or False

False. They vary significantly in size.

Define SEISMIC WAVES:

They are vibrations that travel through the Earth. Depending on the density and strength of material they pass through, seismic wave travel at different speeds - faster through solid rock than through liquid. They use these waves to help determine the earth's composition. Seismic waves are also measured to see how strong an earthquake was.

CONTINENTAL DRIFT is:

The theory that continents can drift apart from one another and have done so in the past.

Alfred Wegener:

Wrote about his theory, Continental Drift.

PANGEA:

All the separate continents of today were once joined in a single landmass that was called Pangea, meaning "all earth" in Greek. There was one huge continents 245 million years ago, but have drifted to their current locations.

SEA-FLOOR SPREADING:

Process by which new oceanic lithosphere is created as older materials are pulled away.

Name 4 pieces of evidence to prove PANGEA/CONTINENTAL DRIFT

1. Same index fossils on different continents
2. Mountains line up
3. Glacier scars line up
4. They all fit together like a puzzle

PLATE TECTONICS is:

The theory that the Earth's lithosphere is divided into tectonic plates that move around on top of the asthenosphere.

PLATE MOTION is affected by:

Heat and gravity.

Name 3 ideas why plates move:

1. RIDGE PUSH
2. CONVECTION
3. SLAB PULL

CONVECTION happens when:

hot materials from the deep Earth rise while cooler material near the surface sinks. When warmer material cools, it becomes denser and begins to sink back down, dragging plates sideways.

RIDGE PUSH happens when:

The ocean lithosphere is higher than it is where it sinks beneath continental lithosphere, making oceanic plates slide down.

SLAB PULL happens when:

the denser oceanic lithosphere sinks and pulls the rest of the tectonic plate with it.

Name 3 tectonic plate BOUNDARIES:

1. CONVERGENT BOUNDARIES
2. DIVERGENT BOUNDARIES
3. TRANSFORM BOUNDARIES

Name the 3 types of CONVERGENT BOUNDARIES:

1. Continental/Continental Collisions
2. Continental/Oceanic Collisions
3. Oceanic/Oceanic Collisions

Define CONVERGENT BOUNDARIES:

When two tectonic plates push into one another.

Define SUBDUCTION ZONE:

The region where two plates collide causing the oceanic plates to sink down into the asthenosphere.

Define DIVERGENT BOUNDARIES:

When two tectonic plates move away from one another. Divergent boundaries are where new oceanic lithosphere forms. (it can happen on continents too).

Define TRANSFORM BOUNDARIES:

When two tectonic plates slide past each other horizontally. Because tectonic plates are not smooth, they grand and jerk as they slide, producing earthquakes. Ex. The San Andreas Fault in CA.

STRESS is:

The amount of force per unit area that is put on a given material

Name 3 things that deform the Earth's crust:

1. STRESS
2. FOLDING
3. FAULTING

Name 2 types of STRESS:

1. COMPRESSION
2. TENSION

COMPRESSION STRESS is:

When two plates collide. Ex. The Rocky Mountains

TENSION STRESS is:

When forces act to stretch an object and occurs at divergent plate boundaries.

FOLDING:

occurs when rock layers bend due to stress. The two most common types are anticlines and synclines. Monocline is when both sides are still horizontal, but there is a fold in the middle.

FAULT:

is the surface along which rocks break and slide past each other.

Name 3 types of Faults:

1. Normal Fault
2. Reverse Fault
3. Strike Slip Faults

NORMAL FAULT:

Causes the hanging wall to move down relative to the foot wall. Normally caused by tension that PULLS rocks apart.

REVERSE FAULT:

Causes the hanging wall to move up relative to the footwall. Normally caused by compression that PUSHES rocks together

STRIKE-SLIP FAULT:

Occurs when opposing forces cause rock to move horizontally.

Name 3 types of mountain building:

1. Folded Mountains
2. Fault-Block Mountains
3. Volcanic Mountains

FOLDED MOUNTAINS:

Form when rock layers are squeezed together and pushed upward.

FAULT-BLOCK MOUNTAINS:

Where tectonic forces put enough tension on the Earth's crust that lot of normal faults are created. Then the faulting causes large blocks of the Earth's crust to drop down relative to other blocks. Ex. The Tetons

VOLCANIC MOUNTAINS:

When oceanic and continental plates collide. Most volcanic mountains are formed in subduction zones and are the result of molten rock erupting onto the Earth's surface. Volcanic mountains are formed from new material being added to the Earth's surface.

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