Everybody Read to Find Out: • How the layers of the earth are ordered and what the names of the layers are
EARTH • The center of the earth consists of hot rock and is called the inner core (solid iron and nickel). • There is also an outer core (liquid iron and nickel). • The next level is hot, molten rock called mantle. • The layer that we walk on is the crust.
EARTH • The Crust • The earth’s outer layer of rock • 5-20 MILES THICK!! • Has mountains, ocean floor, volcanoes, and continents
EARTH 2. The Mantle • The second layer between the crust and outer core • Is solid rock except for the part next to the crust, where there is thick liquid • 1,800 MILES THICK!!
EARTH • The Outer Core • The outer part of the core is liquid and HOT! • It gets hotter the deeper you go (around 9,000 degrees F in the center—your oven only goes to about 600 degrees F). • It’s so hot that rock melts. Melted rock is called MAGMA. • 1,400 MILES THICK!
EARTH • The Inner Core • 800 MILES TO CENTER! • Shaped like a ball, or sphere. • Solid
Everybody read to find out: • What makes the earth’s crust move • The definition of plate tectonics • What forces act on Earth’s crust (P. C-18-C-21)
The inside of the earth is very hot, and it always releases a lot of energy. Effects Cause This energy causes things to move in the earth (rocks, plates, etc.) The earth has many different landforms. They include mountains, hills, rivers, canyons, plateaus, and many other things.
Plate Tectonics • Plate Tectonics a. Explains how plates (large bodies of rock) move slowly around the earth on partly melted rock • Plates a. A large section of the earth’s crust that moves as one unit b. There are 8 large plates and several smaller plates.
Plate Tectonics As these plates float, they move in three different ways. Each way that they move has a special name associated with the boundary where two plates meet. Fault -- the place where two plates meet. Types of plate movement: 1. Convergent -- where two plates move together 2. Divergent – where two plates are drifting apart. 3. Sliding – where the plates slide past one another.
Volcanoes • What are they? a. An opening in the earth’s surface. • How do they form? a. Magma (melted rock) from the mantle sometimes pushes upward. b. The crust usually blocks it, but sometimes it seeps through cracks in the crust. When it builds up inside a “magma chamber”, the pressure starts to increase and then---BAM!!!
3.What happens after they erupt? a. The magma explodes through a main vent in the volcano. b. A deep hole called a crater is often left on top of the volcano. c. The erupting magma is called lava. d. Gases, volcanic bombs, ash, and melted rock also burst from inside the volcano. e. The lava layers and ash layers build up around the outside of the volcano. 4. Interesting Facts: a. Hawaii was formed by volcanoes erupting in the Pacific Ocean. b. The two types of volcanoes are erupting and oozing. c. Lava can flow up to 50 mph but usually just flows 10 mph.
Connecting Learning • Do you think Pangaea once existed? Why or why not? • Use the diagram on p. 21. In which direction does each of the continents seem to be moving? How might Earth look several million years from now? • Look at the map of the earthquakes and volcanoes and Earth’s plates (p. 22). What do you notice? • What are you wondering now?
Earthquakes • What causes earthquakes? • a. Sudden shifts in the earth’s rock layers cause earthquakes • 2. The focus, or epicenter, is where the earthquake begins. • During an earthquake, the plates might: • a. Meet in a rubbing way (shoulder to shoulder)--sliding • b. Spread away from each other (divergent) • c. Meet in a pushing way (subduction)-- convergent
4. New plates can be created during an earthquake (especially at mid-ocean ridges). 5. A seismograph is used to measure earthquakes. a. The Richter scale is used to give them a number. b. People cannot feel earthquakes between a 1-2 on the scale. c. An earthquake that receives a 7-8 destroys buildings. • Earthquakes a. Shake and destroy land, homes, and buildings b. Create land by creating mountains and valleys
3 Different Types of Rocks Scientists classify rocks in 3 main groups based on how they were formed. 1. Igneous Rocks (Fact: Igneous means “fiery”) a. How they form: When magma reaches the surface, it becomes lava. b. This hot, molten rock cools and hardens to form igneous rock. c. Characteristics: Igneous rocks vary in size, shape, color, and texture. Examples: basalt, pumice, obsidian
Sedimentary Rocks a. Form in water from “sediment”, which is grains and bits of rock that were created by erosion or weathering. b. Fact: The sediment builds up over many years and becomes cemented together to form sedimentary rock. c. Characteristics: These rocks are layered. The layers tell the story about how the rock was formed. They can also have fossils, which tell a story, too! d. Examples: sandstone, limestone, shale, and conglomerate
Metamorphic Rocks (means “change”) a. Formed from another rock by heat and pressure. b. Usually form beneath the earth’s crust (which means they often heat up and become magma again—it’s a cycle—the Rock Cycle!) c.Fact: Both igneous and sedimentary rocks can change into metamorphic rocks. d. Characteristics: These rocks are usually harder than the rocks that they were at first. e. They may have “bands” which look like stripes or layers from different minerals pressed together by the heat and pressure. Examples: gneiss, slate, schist
Rocks and Minerals • Minerals are made up of elements and compounds. • Rocks are made up of minerals. • As minerals form, their atoms and molecules form patterns that are crystal shapes.
4. Scientists identify minerals by: • luster (how light bounces off of it) • streak (color of powder left when a mineral is rubbed against a surface) • hardness (Moh’s Hardness Scale) • cleavage (how a mineral breaks apart) • density • color
Weathering and Erosion • Physical (mechanical) weathering happens when the earth’s crust is exposed to water, air, and changes in temperature. a. Rocks can wear away, making smaller rock pieces, or sediments. b. Freezing water expands, or takes up more space and can cause rocks to crack. • Chemical weathering happens when gases in the air chemically react with other elements and minerals. a. Acid rain can dissolve limestone rocks.
Erosion a. Is the carrying away of weathered rock by gravity, water, wind, and ice b. Erosion can wash away boulders and mountains! Examples: soil washed onto the sidewalk, crumbling rocks on buildings, holes in the road, cracked sidewalks, plants/roots growing by sidewalks, muddy streams
Examples of Erosion and Weathering • Sea cliffs form when a rocky shore erodes at approximately the same rate throughout an area. This results in a steep walled structure. The cliff moves landward as the waves attack its base.
Examples of Erosion and Weathering • A gully caused by severe rainstorms.