Chapter 6 Lesson 2 PDF

Lesson 2 How Does Earth’s Crust Change? Ii Why It Matters... Scientists that study volcanoes are called volcanologists. They wear suits designed to protect them from the hot melted rock that flows out of volcanoes. When melted rock reaches Earth’s surface, it cools and hardens quickly. When a volcan...

Lesson 2 How Does Earth’s Crust Change? Ii Why It Matters... Scientists that study volcanoes are called volcanologists. They wear suits designed to protect them from the hot melted rock that flows out of volcanoes. When melted rock reaches Earth’s surface, it cools and hardens quickly. When a volcano erupts, Earth’s surface changes. Ii 0 CJ2 Chapter 6 PREPARE TO INVESTIGATE Inquiry Skill Use Models You can use a model of an object to better understand or describe how it works. Materials small plastic cup modeling clay grass, leaves, twigs red and yellow food coloring liquid dishwashing detergent dropper baking soda vinegar metric measuring cup plastic spoon goggles a Volcano Blast! procedure o Collaborate Work in small groups to build a volcano. Place a plastic cup on a flat surface. Use modeling clay to build a volcano around the cup. Leave an opening in the volcano, directly over the opening in the cup. Place grass, leaves, and twigs around 0 the sides of the volcano. Stand some of the twigs up to look like trees. Safety: Wear goggles during this activity. put 2 spoonfuls of baking soda 0 Carefully in the cup. Add 1 drop each of red and yellow food coloring. Use a dropper to add 6 drops of dishwashing detergent. Stir the mixture. STEP 4 o Observe Pour 125 mL of vinegar into a metric measuring cup. To cause your model volcano to “erupt,” slowly add the vinegar to the mixture. Record your observations in your Science Notebook. Conclusion 1. Use Models What happened to the grass, leaves, and twigs on the sides of the volcano during the eruption? 2. Hypothesize How do you think a teal lava flow would affect the land near a real volcano? Investigate More! Design an Experiment Use more modeling clay to change the shape of the volcano. Then cause the volcano to erupt again. How does the shape affect the lava flow? Changes in Crust VOCABULARY core crust earthquake fossil igneous rock mantle metamorphic rock mineral sedimentary rock p. C14 MAIN IDEA Earth is made of three layers. Earth’s surface may change slowly or quickly. p. C14 p. C21 p. C22 Earth’s Layers P Cl 8 p. C14 Earth is made of three layers. Imagine using a peach as a model of Earth. The skin of the peach represents the thin outermost layer of Earth, called the crust (kruhst). The fruit beneath the skin represents Earth’s mantle (MAN tl). The mantle is the middle layer of Earth. The pit of the peach represents the core (kohr), Earth’s deep innermost layer. Earth’s crust is most familiar to you. It is where humans and other organisms live. Underground caves and the bottom of the ocean are also part of the crust. p. Cl B p. C16 p. C18 READING SKILL Classify Use the chart to list and describe the main layers of Earth. - f:cir*:...i LI Earth’s crust is the layer of Earth on which we live. This cave is part of Earth’s crust. IL1I C14 Chapter 6 Lesson 2 1 JJL. ! I I ) The mantle is the thickest layer. It is made 0f rock. Some rock of the mantle is a thick fluid that will move when it is squeezed. The core extends to the center of Earth. It js made mostly of the metals iron and nickel. part of the core, called the inner core, is 5olid. The outer core is melted metal. You may wonder why some of the materials inside Earth are melted. The temperature of Earth increases toward the center. Deep inside Earth, it is hot enough to melt rock and metal. 5 CLASSIFY On which layer of Earth are living things found? Inside Crust The crust is Earth’s thin outer skin. Mantle The mantle is the thickest layer. Outer core The outer Core is melted metal. — Inner Core The inner core is like a solid metal ball. h The crust is much thicker under land than under the oceans. V Minerals Have you ever played a game to guess an unknown object? The first question you might ask is whether the object is an animal, vegetable, or mineral (MIHN ur uhi). A mineral is a material that is found in nature and that has never been alive. There are many kinds of minerals. Metals, such as gold and iron, are minerals. The graphite (GRAF yt) in your pencil is a mineral. Salt that you put on food is also a mineral. Minerals have certain properties that can be used to identify them. Color, hardness, and texture are some properties of minerals. Gold is yellow and shiny. Graphite is black, soft, and feels greasy. The mineral talc is so soft you can scratch it with a fingernail. ii CLASSIFY What properties can be used to classify minerals? Ii I Rock Gabbro is a rock that contains the minerals shown. is Mineral Pyroxenes are a hard, dark-green mineral, important rock-forming minerals. Mineral Olivine CC16 ‘, Chapter 6 Lesson 2 Mineral Feldspars are common minerals in Earth’s crust. Titanium is a lightweight metal used in eyeglass frames and airplanes. titanium L. Quartz is used in the glass that covers this watch and in the parts that help it run. ZinCite used to make sunscreen. bauxite I quartz ij Talc, the softest mineral, is used to make talcum powder. zincite Aluminum comes from the mineral bauxite. talc How Rocks Form Rocks make up Earth’s crust. Rock is a solid material made of minerals. A rock may contain one mineral or several minerals. The rock contains quartz, feldspar, mica, and hornblende. Rocks are grouped according to how they are formed. There are three kinds of rock. Igneous rock (IHG nee uhs rahk) forms when melted rock from inside Earth cools and hardens. Sedimentary rock (sehd uh MEHN tuh ree rahk) forms when sediment, or sand and small bits of stone are glued, together. Metamorphic rock (meht uh MAWR fihk rahk) forms when other rocks are changed by heat and pressure. Each type cemented, or of rock has specific traits. Traits of Rocks r Ii ii Igneous Sedimentary Metamorphic obsidian red sandstone slate I Rock J Texture glassy, smooth, no grains gritty, medium grains smooth, small grains, wavy bands Color black red-brown dark gray Layering no yes yes — C18 Chapter 6 Lesson 2 Th Types of Rocks Sedimentary Rock Igneous If melted rock cools inside Earth’s crust, it hardens slowly. Then large mineral grains form. If rock cools on Earth’s surface, it hardens quickly. Then, if mineral grains form, they are small. I Sedimentary rock forms from layers of sediment that are deposited, usually on the bottom of rivers, lakes, and oceans. The layers become pressed together, and they harden to form rock. You can often see layers of different colors in sedimentary rocks. Metamorphic Metamorphic rock forms when rock inside Earth is heated and squeezed. Although the heat and pressure are not enough to melt the rock, they change it into a different kind of rock. Sedimentary I. p I I What determines whether a rock is classified as igneous, sedimentary, or metamorphic? 0 ‘N- CLASSIFY (;9l Slow Changes Did you ever build a sand castle on the beach, only to have waves wash it away? Water changes Earth’s crust by breaking down rocks and carrying them away. Unlike sand washing away at the beach, the process of breaking down rock is slow. Wind carrying sand can also break down rock. Wind, which is moving air, blows against rock. Over time, the sand it carries wears the rock away. Ice changes the shape of Earth’s surface, too. A glacier is a large mass of slowmoving ice. Glaciers carrying small rocks grind down large rocks. As glaciers move over some rocks, they pick up the rocks. When the glacier stops moving or melts, it drops the rocks. The sedimentary rock layers of the Grand Canyon formed over millions of years. V C20 Chapter 6 Lesson 2 A The action of water on rock causes changes to the rock over time. !,J Changes A When a volcano erupts, new landforms may form and old ones may be destroyed. Although it is rare to feel them move, parts of Earth’s crust are always moving. A crack in the crust, called a fault (fawlt), may form where the crust moves. When parts of the crust move against each other, tress can build up. Over time, the stress can become so it that the crust suddenly snaps back. An earthquake TH kwayk) is caused by a sudden movement of large [tlOflS of rock beneath Earth’s surface. Earthquakes LSe rapid changes to Earth’s surface. Mountains can n’i as the crust bends, folds, and is pushed up. If two sections of crust pull apart, melted rock may A Lava forms new e to the is rock surface. At the surface, this melted crust when it cools 1 lava. A volcano (vahi KAY noh) is an opening in and hardens. CfllSt through which hot ash, gases, and melted rock from deep inside Earth to the surface. What are two causes of rapid changes th’5 surface? C21 I Fossils and Earth’s Past A fossil (FAHS uhl) is the remains of a once-living plant or animal. Fossils can tell stories about living things of long ago and how they have changed over time. Fossils can also tell what Earth’s surfac e was like long ago. Scientists study fossils to find clues about the environment in which the fos sil plant or animal once lived. For examp le, fossils of trees and a fly found near the South Pole have helped scientists understand that this area was once mu ch warmer than it is today. By examining fossils of plants or animals that no longer exist, scientists can tell what they looked like. By learning the age of the rock layers aro und a fossil, they can tell when the plant or animal that formed the fossil lived. CLASSIFY, How can scientists use a fossil to tell when an animal once lived? A living thing dies and is buried under layers of sand and soil. Over a long period of time, the sand and soil harden and turn into rock. Most fossils form from living things tha t had hard parts, such as bones, shells, and woo d. V As the crust moves, rock containing the fossil is slowly brought closer to the surface. C22 Chapter 6 Lesson 2 Review 11 o MAIN IDEA What are Earth’s three layers? Minerals can be classified according to their color, hardness, and texture. I I -‘ $ The three types of rocks are igneous, sedimentary, and metamorphic. Slow and rapid changes take place on Earth’s surface. OVOCABULARY How do igneous rocks form? Give an example of an igneous rock. o READING SKILL: Classify What are three kinds of rocks? o CRITICAL THINKING: Analyze Which kind of rock is most likely to contain fossils? Why? o INQUIRY SKILL: Use Models What materials could you use to model the layers of Earth? Explain your choices. TEST PREP Which of the following is NOT a mineral? for O0000 WRITING A. granite Home and School Persuasive Suppose you find a deep, rocky canyon with a stream at the bottom. Do you suppose the canyon was created by gradual changes, or by a sudden change? Write a persuasive essay to explain your choice. Be sure to include detailed evidence. B. graphite C. gold D. feldspar 2 Tech no logy Visit www.eduplace.com/scpI to find out more about changes in Earth’s crust. SOCIAL STUDIES Historical Interview At 5:1 2 A.M., on April 1 2, 1 906, one of the worst earthquakes in American history Shook San Francisco. Write a news broadcast as if You were a reporter at the scene. L C23 Readers’ Theater Volcano Visit Watching Lava Form Land What does lava look like? The Mendez family is about to find out. They are hiking near Kilauea (kee law AY uh), an active volcano in Hawaii Volcanoes National Park. Lava is erupting from a vent on the southeast side of the volcano. A park ranger is leading them to the perfect viewing spot. k Alana Smith: park ranger I. Andre: age 8 Kim: age JO Margaret Mendez: mother of Andre and Kim Bill Kato: volcanologist Chapter 6 Lesson 2 6. V READING OQO anger Smith: OK, we’re almost at the lava flow. Is everybody ready to walk out to the observation area? Kim: I can’t wait to see real lava! How close will we be? Andre: Are you sure we’ll be safe? anger Smith: Just follow me. I’ve been leading tours here for 15 years. You’ll be a safe distance from the flow. But you’ll still feel the lava’s heat and smell volcanic gases. Andre: Wow, it’s hotter already. Is it always like this? Ranger Smith: It’s extra hot today because there’s a big flow from a vent on the southeast side of the volcano. Kim: But I thought lava burst out of the big hole at the top. Ranger Smith: That big hole, or crater, is called a caldera (kal DAIR uh). Lava did flow from the caldera in 1983, when Kilauea started erupting. But lava also flows from the volcano’s vents, tubes, and small craters. Hawaiian volcanoes are famous for smooth, gentle flows. They’re called pahoehoe (puh HOH eh hoh eh) flows. Pahoehoe is a Hawaiian word for “runny.” Margaret Mendez: That lava looks like a river of fire! Kim: How hot is it? Ranger Smith: When lava erupts, it’s temperature is about 1,100 degrees Celsius. Andre: Hey, something smells terrible! What is that? tAndre pinches his nose.] ,r -___ — Ranger Smith: That’s sulfur dioxide, a volcan ic gas. It helps make lava erupt. Kim: How? PACIFIC OCEAN Ranger Smith: Combined with the pressure and heat inside Earth, it pushes the lava up and out of the surface. Margaret Mendez: Ipointing] Who’s that man in the astronaut suit? LEnter Mr. Kato] Ranger Smith: That’s Bill Kato. He’s a vol canologist. Bill works at the volcano observatory. He we ars that heat-resistant suit and face mask when he works close to lava. Hi, Bill. What are you working on tod ay? Bill Kato: Aloha, Ranger. I’ve been collecti ng lava samples and measuring craters. I’m lookin g for clues that will help predict eruptions. The more that scientists know about volcanoes, the safer people wil l be. Margaret Mendez: Oh, wow! The sight of that lava flowing to the sea is breathtaking! C26 Chapter 6 Lesson 2 s a lot of steam down by the water. How come? There’ tAdre When the hot lava touches the cool water, it KatO BW clouds of steam. creates big, puffy been studying lately, Bill? aflg Smith: What else have you the volcano fll Kato: Well, I’m writing a report on how In the past 20 years, Kilauea has has affected our coastline. Hawaii. added almost 550 acres of land to the Big Island of That’s nearly 550 football fields! Margaret Mendez: How does that happen? Bill Kato: When flowing lava cools, it hardens and forms new crust on Earth’s surface. When the lava flows down to the ocean, it extends the coastline and makes the island bigger. Ranger Smith: Well, it’s getting late, and we have a long walk back. We’d better get going, folks. Thanks for all the info, Bill! Bill Kato: Anytime. Aloha! Ranger Smith, Margaret Mendez, Andre, and Kim: Aloha! 1. READING CHECK From what parts of a volcano might lava erupt? 2. WRITE ABOUT IT Describe what happens when lava flows into the ocean. 3. TALK ABOUT IT Discuss why volcanologists study volcano activity.