April18th, 2008 BellRinger Objectives Homework Examples 1, 2, 3 pgs 95-97 in PSAE Coach book Objectives Describe the structure of Earth Explain how Earths dynamic processes create a changing landscape Homework What type of evidence was necessary to prove that Pangea existed?

April 21st, 2008 BellRinger Objectives Homework Complete questions on pg 102, 103, & 105 Objectives Explain how Earths dynamic processes create a changing landscape Homework Complete MC questions. This will be graded!!

Chapter 28 THE CHANGING EARTH

The Layers of Earth

The Layers of Earth Crust- a thin surface covering the Earth. 2 kinds: Oceanic & Continental What is a crack in the crust called?? Mantle- a thick molten layer between the core and the crust Outer Core- molten iron, nickel, and oxygen Inner Core- solid iron and nickel The core’s temperature ranges between 2,000 oC and 5,000 oC…hot, hot, hot!

Rock Cycle pg 103

Igneous Rocks Form at the surface from lava and inside the crust from magma that has cooled Rocks that cool slowly are rougher in texture Rocks that cool fast have smoother textures

Igneous Rock

Basalt

Granite

Sedimentary Rocks From as a result of weathering and erosion Formed by processes mainly at the Earth’s surface

Metamorphic Rocks Form under conditions of extreme pressure and temperature Any type of rock can change to metamorphic under these conditions

The Surface of Earth Is there a pattern??? YES!!!

Continental Drift How is this possible? The idea that the continents were once one landmass; a “super-continent” named Pangea How is this possible?

mantle convection Heat transferred from the core to the mantle produces a slow convection of the material in the mantle Thermal Convection Demo

Sea Floor Spreading Mid-Ocean Ridges: mountain ranges on the ocean floor The closer you get to a ridge, the younger the ocean floor. Scientists concluded that the “new” land must be coming up through the ocean ridges

The Theory Of Plate Tectonics Explanation of how continents move Earth's outer layer is made up of tectonic plates, which are moving explains the how and why behind mountains, volcanoes, and earthquakes What is the area called where 2 plates meet?

Plate Boundaries

Divergent Plate Boundaries Plates are moving apart, allowing molten material to rise up and create new crust Mid-ocean ridges Sites of earthquakes and volcanoes

Convergent Plate Boundaries Occurs when two plates approach each other Subduction: one plate slides under another Often the site of volcanoes Collision can also occur between approaching plates Mountains form

Convergent Plates Subduction: Collision:

Transform Plate Boundaries Occurs when 2 plates slide past each other No crust is created or destroyed Earthquakes What “famous” transform plate boundary is located in the US?

Review of Boundaries Define each term. Have the students as a class mimic the movement of divergent, convergent, and transform boundaries using their hands. Use the hyperlinks as visuals while discussing each type of plate boundary.

Facts & Figures: Earthquakes Largest EQ recorded in the US: 9.2 Largest in world: 9.5 500,000 detectable EQ’s each year. More damage is caused indirectly from the EQ, not the EQ itself. 10,000 EQ’s will develop in southern California this year. However, most will not be felt Powerful EQ’s rocked the Midwest in the 1800’s. One recorded a magnitude of over 8 and caused church bells to ring in Boston Massachusetts Deadliest EQ: China in 1557, killing 830,000 people

Earthquakes Defn: Vibrations of the earth’s crust from the movement of plates along faults As plates move, they stretch/compress, and stress builds up When the rocks break or change shape, they release stored energy in the form of movement LIKE A RUBBER BAND! This creates seismic waves that move through Earth

Earthquakes

Seismic Waves Body Waves Surface Waves originate from the center of an EQ 2 kinds: P waves & S Waves Surface Waves – Move along the surface of the Earth

Measuring Earthquakes Richter scale: Related to the amplitude of the seismic waves More accurate for earthquakes that are near Mercalli scale: Uses 12 descriptive categories that describe the damage caused by earthquakes

Where do Earthquakes Occur? Along plate boundaries, faults

Earthquakes in the US: SAN ANDREAS FAULT A well known transform boundary where the Pacific plate and North American plate meet Average rate of motion across the San Andreas Fault is 2 in./yr. (3 million years L.A. will be next to S.F.)

Earthquakes in the US: OTHER FAULT LINES Do EQ’s occur anywhere else in the US? YES!...it’s been a while, but there are other fault lines in the US. New Madrid fault in Midwest 250 miles long Last major EQ in 1895 Eastern US Last major EQ in 1886 Why would an EQ be so damaging in these areas today?

Where do Volcanoes Occur? Most volcanic activity is associated with plate boundaries.

Where do Volcanoes Occur? Most Volcanoes occur within the Ring of Fire!

Additional Sites of Volcanoes Subducting plates beneath the ocean floor can create an island arc. This is how the Hawaiian Islands were formed.

Mount Vesuvius

Mount St. Helens