Earth's Internal Heat - Sorsogon National High School PDF

**Sorsogon National High School** **SELF-DIRECTED LEARNING ACTIVITY SHEET IN EARTH AND LIFE SCIENCE (MODULE 6)** Name of Learner: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Grade Level & Section: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ **I. LEARNING OBJECTIVES** - *des...

**Sorsogon National High School** **SELF-DIRECTED LEARNING ACTIVITY SHEET IN EARTH AND LIFE SCIENCE (MODULE 6)** Name of Learner: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Grade Level & Section: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ **I. LEARNING OBJECTIVES** - *describe where the Earth's internal heat comes from. (S11/12ES-Ib-14)* **II. PRESENTATION OF THE LESSON:** Earth's internal structure is divides into layers based on the differences in chemical composition and on the basis of changes in physical properties. Compositionally, Earth is divided into a thin outer crust, a solid, rocky mantle and a dense core. - **Layers defined by Composition** - *Crust:* a thin rocky outer layer that varies in thickness. It is estimated to extend roughly 7 km in oceanic regions and continental crust averages for about 8-40 km and reaches as far as 70 km in mountainous regions. Crust are further separated into two regions (a) oceanic crust and (b continental crust. a. Oceanic crust- a basaltic composition with a density about 3.0g/cm^3^ and it is believed to be younger (180 million years or less) than the continental crust. b. Continental crust- found in the upper region of the crust and composed of granitic rocks and lower crust is more akin to basalt. It has a density for about 2.7g/cm^3^ and can be as old as 4 billion years. - *Mantle:* can be found below the crust to a depth of 2900 kilometers. And uppermost mantle is composed mostly of igneous rock peridotite and changes at greater depths. - *Core:* can be found below mantle and its sphere has a radius of 3486 kilometers with composition mostly of an iron-nickel alloy. It has a density of nearly 11g/cm^3^. - **Layers defined by Physical Properties** - *[Lithosphere]*- found in crust and uppermost mantle (about 100km thick) and commonly cool, rigid and solid. - *[Asthenosphere]*- found beneath the lithosphere and upper mantle and can reach to a depth of about 660 kilometers. It is commonly displayed as soft and weak layer that is easily deformed. - *[Lower Mantle]*- more rigid layer and can extend for about 660 to 2900 km. In this layer rocks are very hot and capable of gradual flow. - *[Inner Core]*- behaves like a solid and its sphere has a radius of 1216 km. - *[Outer core]*- has a liquid layer and can be as thick as 2270 km. Convective flow of metallic iron generates Earth's magnetic field. - [Discovering Earth's Layers] - Moho: separates crust from underlying mantle. And velocity from seismic waves increases abruptly below 50km of depth. - Crust: early recordings of seismic data and drilling technology indicate that the continental crust is mostly made of lighter, granitic rocks. - Mantle: composition is more speculative and some of the lava that reaches Earth's surface comes from asthenosphere within. - Core: Earth's core is thought to be mainly dense iron and nickel, similar to metallic meteorites. The surrounding mantle is believed to be composed of rocks similar to stony meteorites. **Mechanisms of Plate Motion** - Scientist generally agree that convection occurring in the mantle is the basic driving force for plate movement. Convection currents in the mantle provide the basic driving forces for plate motions. - A ***convection current*** is the continuous flow that occurs in a fluid because of differences in density. On the other hand, ***convection flow*** is the motion of matter resulting from changes in temperature. - The hot, but solid rock of mantle behaves in plastic way- that is, it can flow slowly over geologic times. - The heat sources for mantle convection include energy released by radioactive isotopes in the mantle and heat from the core itself. - In the process called *whole mantle convection*, rock rises from the lower mantle toward the top of the mantle, then sinks back down. This process takes millions of years. **Causes of Plate Motion** The sinking of cold ocean lithosphere directly drives the motions of mantle convection through slab-pull and ridge-push. Some scientists think mantle plumes are involved in the upward flow of rock in the mantle. a. **[Slab-pull]** is a mechanism that contributes to plate motion in which cool, dense oceanic crust sinks into the mantle and "pull" the trailing lithosphere along. It is thought to be primary downward arm of convective flow in the mantle. The addition of force coming from gravity pulls old ocean lithosphere, which is relatively cold and dense, down into the deep mantle. b. **[Ridge-push]** causes oceanic lithosphere to slide down the sides of the oceanic ridge under the pull of gravity. It may contribute to plate motion, an example of this is when stiff ocean lithosphere slides down the asthenosphere that is elevated near mid-ocean ridges. c. **[Mantle plumes]** are masses of hotter-than-normal mantle material that ascend toward the surface, where they may lead to igneous activity. The unequal distribution of heat within Earth causes the thermal convection in the mantle that ultimately drives plate motion. **III. LEARNING TASKS:** A. Practice Task 1. Use the figure of Earth's structure to write the letter(s) that represents each of the following layers. mantle \_\_\_\_\_ continental crust \_\_\_\_ oceanic crust \_\_\_\_\_ core \_\_\_\_ inner core \_\_\_\_ asthenosphere \_\_\_\_\_ outer core \_\_\_\_\_\_ lithosphere \_\_\_\_\_\_ B. Practice Task 2. Sequencing: After you read, complete the sequence of layers in Earth's interior.  **IV. GENERALIZATION:** Choosing from the list of key terms, furnish the most appropriate response for the following descriptions. \_\_\_\_\_\_\_\_1. soft, weak rock with some melting. \_\_\_\_\_\_\_\_2. liquid iron-nickel alloy that generates Earth's magnetic field \_\_\_\_\_\_\_\_3. cool, rigid crust and uppermost mantle. \_\_\_\_\_\_\_\_4. solid iron-nickel alloy **V. EVALUATION:** 1\. Choose the letter of the basic force that drives plate tectonics. 2\. What happens to the material involved during convection? 3\. A \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ is the continuous flow that occurs in a heated fluid because of differences of temperature and density. 4\. the mechanism called \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ causes oceanic lithosphere to slide down the sides of oceanic ridge. 5\. The mechanism that is the main downward component of mantle convection is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. 6\. Is the following sentence true or false? The upward flow of material in the mantle convection consists of mantle plumes of rising hot rock. \_\_\_\_\_\_ 7\. The feature in the diagram below where rock is coolest and most dense is the a\. lower mantle b. descending oceanic plate c\. rising plume d. oceanic ridge 8\. Circle the letter of the statement that best describes the whole-mantle convection model. a\. Rock magnetism changes as rock layers melt under heat and pressure. b\. Hot oceanic lithosphere descends into the mantle, and cold mantle plumes heat toward the surface. c\. Hot mantle plumes move heat toward the surface d\. Convection in Earth's molten outer core transfers heat directly to the lithosphere. 9\. What causes thermal convection in the mantle? \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 10\. What causes thermal convection in the mantle? \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ **Prepared by BRYAN PHILIP J. BEJERANO, Special Science Teacher I** **Language Critic: FRANCOIS L. DETERA, Master Teacher I** **Content Editors: FRANCOIS L. DETERA, Master Teacher I** **ANNE E. MANCIA, Assistant School Principal II for Academics** **MARILYN B. DIVINA, School Principal I**