Unit 6 Earth’s Dynamic Interior

Structure of the Earth The Earth is made up of 3 main layers: Core Mantle Crust Mantle Crust Outer core Inner core

The Crust This is where we live The Earth’s Crust is made of Continental and Oceanic Continental Crust thick (10-70 km) - buoyant (less dense than oceanic crust) -Older than Oceanic crust Oceanic Crust - thin (~7 km) - dense (sinks under continental crust) - Younger than Continental Crust

Seismic wave an elastic wave in the earth produced by an earthquake Reflecting off plate boundaries and refract

Mantle is the middle layer inside the Earth below the crust About 85 % of Earth’s volume Dense because of heavy elements Divided into three parts

Mantle’s three parts The rigid outer part of the Earth Lithosphere Asthenosphere mesosphere The rigid outer part of the Earth Crust + Upper Mantle = Lithosphere Layer below Lithosphere Largest layer of Mantle Above the outer core

Core=inner core + outer core solid  Made of iron has a radius of about 760 miles  fluid made of iron and nickel  about 2,200 km (1,400 mi) thick

6.2 Tectonic Plates If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.

Plate Tectonics The Earth’s crust is divided into plates which move in different directions This plate motion causes them to collide, pull apart, or scrape against each other Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. Tectonic = deformation of the crust because of plate interaction

Plate Tectonics

Fault crack in the Earth’s crust where plates slide Causes the boundaries between tectonic plates

Epicenter the point on the earth's surface directly above the center of an earthquake

Continental Margin is the shallow water area near the continent Has 3 different features:  continental rise  continental slope continental shelf

6.3 Plate interactions

Effects of Plate Tectonics Landforms caused by plate tectonics: a. rift valleys (divergent boundaries) b. mountain ranges (continental-continental convergent boundaries) c. volcanoes (oceanic-continental convergent boundaries) d. faults (transform boundaries)

Causes of Plate Tectonics Convection Current is the force of plate tectonics hot, plastic-like material from the mantle rises to the lithosphere moves horizontally cools sinks back to the mantle These currents provide enough energy to move the plates in the lithosphere

Mantle Convection   is the slow creeping motion of Earth’s solid mantle caused by convection currents carrying heat from the interior to the planet's surface Hot material rises to the crust, cools and sinks to be reheated and rise again

Plate Boundaries Convergent Boundaries Transform Boundaries There are 3 different plate boundaries: Divergent Boundaries Convergent Boundaries Transform Boundaries

Divergent Boundaries = the boundaries between 2 plates that are diverging, or moving away from each other.

Convergent Boundaries = the boundaries between 2 plates that are converging, or moving towards each other. There are 3 types of convergent boundaries: An ocean floor plate collides with a less dense continental plate. An ocean floor plate collides with another ocean floor plate. A continental plate collides with another continental plate.

Subduction zone takes place at convergent boundaries one plate moves under another and is forced or sinks due to gravity

 Oceanic-Continental Oceanic-Oceanic   Continental-Continental

Transform Fault Boundaries = the boundaries between 2 plates that are sliding horizontally past one another.

Oceanic trench a long, narrow, deep depression in the ocean floor running parallel to a plate boundary identifies a subduction zone

Slab pull = the motion of a tectonic plate caused by its subduction The motion is driven by the weight of cold, dense plates sinking into the mantle at oceanic trenches

Ridge push There are mountain ridges in the ocean. Gravity pulls them down This causes an outward force on the sides called ridge push

6.4 Natural Hazards

Lava Hot molten ( semi-fluid ) rock coming out of a volcano

seismograph an instrument that measures and records details of earthquakes, such as force and duration