Layers of the EARTH CRUST 5 to 25 miles thick and up to 1,600 F MANTLE 1,800 miles thick and up to 8,000 F OUTER CORE 1,400 miles thick and up to 11,000 F INNER CORE 800 miles thick and up to 13,000 F

The Crust Outer layer km thick 2 types of crust –O–Oceanic (very dense, made of basalt) –C–Continental (less dense, made of granite)

Oceanic and Continental Crust

The Mantle Middle layer Very thick layer

The Core Made mostly of iron 1/3 of the earth’s mass Very hot

Earth’s Layers How are the earth’s layers similar to an egg? Shell=crust Egg white=mantle Yolk=core

Physical Structure of the Earth (5 Layers) Lithosphere- rigid outer layer (crust) Asthenosphere- solid rock that flows slowly (like hot asphalt) Mesosphere- middle layer Outer Core- liquid layer Inner Core- solid, very dense

How is heat transferred? There are three types of heat transfer: radiation conduction convection

Convection currents in the earth’s mantle occur in the _______. Asthenosphere

What part of Earth’s interior is like the soup in a pot? The asthenosphere is like the soup in the pot.

What part is like the burner on the stove? The core and mantle are like the burner on the stove

Describe how convection currents form in Earth’s asthenosphere. Heat from Earth’s core and mantle cause hot columns of mantle material to rise slowly in the asthenosphere At the top of the asthenosphere, hot material spreads and forces the cooler material to sink This cycle has continued for more than four billion years

Tectonic Plates Earth’s crust is broken into about 19 pieces These plates move on top of the asthenosphere

A Theory of Plate Motion

Plates A section of the lithosphere that slowly moves, carrying pieces of continental and oceanic crust The plates fit closely together along cracks in the crust Plates carry the continents or parts of the ocean floor, or both

Plate Tectonics A geological theory that states that pieces of Earth’s crust are in constant, slow motion, driven by convection currents in the mantle Convection Currents: The movement of a fluid, caused by differences in temperature, that transfers heat from one part of the fluid to another

How can Earth’s plates move? The plates of the lithosphere float on the top of the asthenosphere Convection currents rise in the asthenosphere and spread out beneath the lithosphere Geologists believe this causes plate movement

As plates move, they ____, ____, or ____ past each other, producing spectacular changes in the earth’s surface. collide pull apart grind These changes include ____, ____, ____, and ____. volcanoes mountain ranges deep-sea trenches earthquakes

What are Earthquakes? The shaking or trembling caused by the sudden release of energy Usually associated with faulting or breaking of rocks Continuing adjustment of position results in aftershocks

The Focus and Epicenter of an Earthquake The point within Earth where faulting begins is the focus, or hypocenter The point directly above the focus on the surface is the epicenter

Body Waves: P and S waves Body waves –P or primary waves fastest waves travel through solids, liquids, or gases compressional wave, material movement is in the same direction as wave movement –S or secondary waves slower than P waves travel through solids only shear waves - move material perpendicular to wave movement

Surface Waves: R and L waves Surface Waves –Travel just below or along the ground’s surface –Slower than body waves; rolling and side-to-side movement –Especially damaging to buildings

EARTHQUAKES Faults A break in the Earth’s crust where slabs of rock slip past each other

What are the three types of plate boundaries? Transform Boundaries Divergent Boundaries Convergent Boundaries Each type of plate boundary, there is a different type of plate movement

Transform Boundaries A plate boundary where two plates move past each other in opposite directions Crust is neither created nor destroyed

What Earth changing event occurs on a transforming boundary? Earthquakes frequently occur at transform boundaries

Divergent boundaries A plate boundary where two plates move away from each other Most divergent boundaries occur at the mid-ocean ridge Divergent boundaries that occur on land are called rift valleys Example: Great Rift Valley (South Africa) – A 3,000 km crack in the earth

Most divergent boundaries occur at the ____. mid-ocean ridge

Convergent Boundaries A plate boundary where two plates move toward each other Collisions can occur between: – oceanic crust and oceanic crust – oceanic crust and continental crust – continental crust and continental crust

What occurs when plates carrying oceanic crust collide? The more dense plate dives back into the mantle (subduction) The collision between oceanic plates causes deep- ocean trenches

What occurs when plates carrying oceanic and continental crust collide? The more dense oceanic crust sinks and plunges (subducts) beneath the less dense continental crust The collision between oceanic plates and continental plates can cause a volcanic eruption

What occurs when plates carrying continental crust collide? Plates crash head – on causing mighty mountain ranges

Sea-Floor Spreading Sea-floor spreading: The process by which molten material adds new oceanic crust to the ocean floor

What is the process of sea-floor spreading? At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge. Over tens of millions of years, the process continues until the oldest ocean floor collides with the continental crust The more dense oceanic crust subducts (sinks) back into the mantle at a deep- ocean trench

The Theory of Continental Drift

Pangaea The name of the single landmass that broke apart 200 million years ago and gave the rise to today’s continents

Continental Drift A hypothesis that the continents slowly move across Earth’s surface

What is Wegener’s theory of continental drift? Continental drift is the hypothesis that all the continents had once been joined together in a single landmass The continents have slowly moved apart over Earth’s surface

Evidence From Landforms A mountain range in South Africa lines up identical with mountain ranges in Argentina (South America) Evidence From Fossils Glossopteris fossils have been found in rocks in Africa, South America, Australia, India, and Antarctica unexpectedly Seeds could not have travel that far over the oceans to reach other continents Evidence Temperature The Island of Spitsbergen (Artic Ocean) has evidence of tropical plants Deep scratches in rocks were found in South Africa These scratches support evidence of glaciers

What is a Volcano?  A volcano is a mountain that forms when magma reaches the surface of the Earth.  Magma rises because it is less dense than the solid rock around it.

What are the parts of a Volcano? 1.VENT- the vent is the opening from which lava flows. Dust, ash, and rock particles can also be thrown out of the vent!

2. Crater- the top of the volcano. It is a funnel shaped pit. It is formed when the material explodes out of the vent!

3. Volcanic cone- is the pile of lava, dust, ashes, and rock around the vent. It can be found in different shapes!

Types of Volcanoes There are 3 types of Volcanoes: Shield Cinder Cone Composite They are classified by how they form.

Shield Volcano Is wide and somewhat flat. It forms from a quiet eruption. Lava flows out quietly and for great distances.

Cinder Cone Volcano  Has tall, very steep sides.  Has explosive eruptions.  This eruption produces a lot of cinder and ash.

Composite Volcano  Form from explosive eruptions.  Produce a lot of lava and ash.  Is small, with steep sides.

TYPES OF ROCKS Igneous Sedimentary Metamorphic

IGNEOUS ROCKS Formed from molten material including volcanic lava, ash, or bombs as well as magma below Earth’s surface

TYPES OF IGNEOUS ROCKS GRANITE BASALT

SEDIMENTARY ROCKS Made of layers that have been pressed or cemented together Pebbles, sand, silt, or clay are sediments Shells and bones can also be sediments

TYPES OF SEDIMENTARY ROCKS SHALE LIMESTONE COAL

METAMORPHIC ROCKS Rocks that are changed by intense heat and pressure while inside Earth’s surface Igneous, sedimentary, and even metamorphic rocks can be changed into different metamorphic rocks

TYPES OF METAMORPHIC ROCKS SLATEMARBLE

Guide For Reading: What is Wegener’s theory of continental drift? Continental drift is the hypothesis that all the continents had once been joined together in a single landmass The continents have slowly moved apart over Earth’s surface