Earth sciences Quarter 2 : Module 2, Lecture notes of Earth science

Download Earth sciences Quarter 2 : Module 2 and more Lecture notes Earth science in PDF only on Docsity! Earth Science Quarter 2 - Module 1 Weathering of Rocks RDorFrti Department of Education e Republic of the Philippines Earth Science- Grade 12 Alternative Delivery Mode Quarter 2 - Module 8: Weathering of Rocks First Edition, 2020 Republic Act 8293, section 176 states that: No copyright shall subsist in any work of the Government of the Philippines. However, prior approval of the government agency or office wherein the work is created shall be necessary for exploitation of such work for profit. Such agency or office may, among other things, impose as a condition the payment of royalty. Borrowed materials (i.e., songs, stories, poems, pictures, photos, brand names, trademarks, etc.) included in this book are owned by their respective copyright holders. Every effort has been exerted to locate and seek permission to use these materials from their respective copyright owners. The publisher and authors do not represent nor claim ownership over them. Published by the Department of Education — Division of Cagayan de Oro Schools Division Superintendent: Dr. Cherry Mae L. Limbaco, CESO V Development Team of the Module Author: Kim S. Casifio Reviewers: Jean S. Macasero,Ph.D EPS, Evelyn Q. Sumanda, Cely B. Labadan, PhD Illustrator and Layout Artist: Jessica Bunani Cunado, Bismark E. Labadan, Management Team Chairperson: Cherry Mae L. Limbaco, PhD, CESO V Schools Division Superintendent Co-Chairpersons: Alicia E. Anghay, PhD, CESE Assistant Schools Division Superintendent Members: Lorebina C. Carrasco, OIC-CID Chief Jean S. Macasero, EPS — Science Joel D. Potane, LRMDS Manager Lanie O. Signo, Librarian II Gemma Pajayon, PDO II Evelyn Q. Sumanda, School Head Cely B. Labadan, School Head Printed in the Philippines by Department of Education — Division of Cagayan de Oro City Office Address: Fr. William F. Masterson Ave Upper Balulang Cagayan de Oro Telefax: (08822)855-0048 E-mail Address: cagayandeoro.city@deped.gov.ph Perform the procedures below by carefully following each step. Exercise proper precaution in handling materials and/or equipment. After which, answer briefly the guide questions below based from the findings of your activity. bh Pour water in the glass jar. Make sure that it is only half-filled. Put the small and soft rock samples that you have prepared inside the glass jar then cover it tightly. 3. Shake the glass jar for about 2 minutes. (Be careful in shaking the glass. Make sure that the glass you are using is thick) 4. Remove the cover of the glass jar. Replace it with the piece of cloth tied at the brim of the bottle with the use of the rubber band. 5. Turn the glass jar upside down to empty the water in the bottle. 6. When the water is gone, remove the piece of cloth in the glass jar and examine the rock samples that you placed inside. N Questions: 1. What have you observed in your rock samples? 2. What do you think is the purpose of water in the activity? 3. What have you realized in this activity? What Is It WEATHERING The activity that you have performed is a demonstration of rock weathering. Were your rocks broken into pieces? What could have possibly cause it? Well, to understand further the process behind the activity, let us explore first the process of weathering. When rocks and minerals break down into pieces or dissolve, it is called weathering. Weathering happens not just on its own. This is possible through the following agents: water, ice, acids, salts, plants, animals, and changes in temperature. The more exposed the rock is to weathering, the more it becomes very vulnerable to breaking. For example, rocks buried beneath the surface are less vulnerable than those rocks on the surface areas because they are very exposed to agents like wind and water. Once rocks have been broken down into tiny pieces, a process called erosion transports them away into different areas. The process of weathering and erosion is responsible for the creation of some famous landmarks around the world like the Delicate Arch in Utah and Kapurpurawan Rock Formations in Ilocos Norte, Philippines. One of the most natural creation resulted from erosion is the canyon or a deep, narrow channel with steep sides. Figure 2: river canyon formed after years of weathering and erosion A river canyon is made when the pressure from a river cuts deep into the river bed. The sediments then from the river bed were carried downstream (erosion) which resulted to the creation of canyons. The river that lies down at the bottom of the canyon 2 is called entrenched river. What makes it different from other rivers is that the river from canyons do not change its course. For thousands of years weathering and erosion gradually and constantly change the landscape of Earth. Hence, no matter how hard the rock is it cannot resist the forces of nature-weathering and erosion TYPES OF WEATHERING Figure 1: Types of Weathering: Chemical Weathering vs. Physical Weathering The process of weathering is divided in 2 types-physical and chemical weathering. PHYSICAL WEATHERING Physical weathering, also known as mechanical weathering, takes place when rocks are broken into smaller pieces because of any natural or anthropogenic forces. This process only changes the physical appearance of the rock and does not alter any of its composition. The following processes below contributes to the physical weathering of rocks: 1. Frost wedging happens when water gets inside the cracks of rocks. The water inside the rock freezes which cause the crack's expansion. The cracks get deepen and more water enters and freezes. The alternate freezing and thawing episodes breaks the rock into small pieces along the joint lines. Rock wth rack "asad pe AG as — ree” ap aa } Figure 3: Process of Frost wedging 3 2. Abrasion takes place when rocks wear away because of constant collision of loose particles 3. Biological activity is sometimes considered a different type of weathering, biological weathering. However, many still acknowledges it as part of physical weathering as the process only changes the physical appearance of rocks. Biological activity includes plants and animals as agents of weathering. For example, when roots of plants grow, they exert more pressure to rocks which causes them to slowly break. Animals like rabbits can move rock fragments to the surface as they dig into soil. Rocks get to be more exposed to more weathering. 4. Salt crystal growth is another factor of physical disintegration of rocks. The force exerted by salt crystal, formed when water evaporates from the rock's pores or cracks, causes the rock to fall apart. CHEMICAL WEATHERING Chemical weathering on the other hand changes the composition or molecular structure of the rock. For example, when carbon dioxide from the air or soil combines with water, this can dissolve the rock. The process itself is called carbonation. Carbonation produces a weak acid, called carbonic acid. Other processes of chemical weathering includes the following: Erosion because It has 2 types with the following differences SPO Each of these types have __ the following branches | JL What I Can Do Activity 5: Weathering Around Me Direction: Read the statement below and write your answer on the space provided. 34 Check your house for any weathering or eroding edges or surfaces. Is the structure foundation of your house strong or weak? Support your answer SUMMARY Rocks are hard, compact and solid. Once these rocks are exposed to cet in the environment , they continuously break into small pieces and this progé called weathering. Different factors act constantly of rocks to break and change them to soil. These factors include heat, air, water, plants, animals and man. Erosion transports the broken pieces of rocks into different areas. Physical weathering also known as mechanical weathering is the breaking of the physical properties of rocks or disaggregation. Chemical weathering is the breaking of rocks due to the change of its composition Breaking of rocks through physical weathering involves the following processes: frost wedging, abrasion, biological activity, and salt crystal growth. On the other hand, chemical weathering may involve the following processes: hydrolysis, oxidation, dissolution, and microbial activity. Assessment: (Post-Test) Pretest: MULTIPLE CHOICE: Directions: Read each item carefully and choose the letter of the correct answer. Use separate answer sheet of paper. 1. Which of the following human activities results to breaking down of rocks? A. driving B. mining C. hiking D. fishing 2. How do roots of plant break down rocks? A. Roots split the rocks apart. B. Roots heat the rocks causing them to break. C. Roots leave materials on the rocks which causes it to rust. D. Roots lose its main composition because of roots’ absorption capability. 3. How does temperature break down rocks? A. Rocks break when it is cooled. B. Rocks break when it is heated. C. Rocks break when it is not exposed to water. D. Rocks break when it is heated and then cooled. 4. Some animals like the rabbits and moles dig up soil for shelter or to find food. How do their activity contribute to the breaking down of rocks? A. The digging of those animals breaks the rocks into small pieces. B. Small rocks are being exposed to sunlight. C. Animals stay in the dug holes and causes the rising of temperature inside. D. The food that these animals bring underground causes the breaking of rocks. 5. This process happens when water, people, animals wear away bits of rocks. A. fermenting B. Mountain building C. weathering D. erosion 6. Which of these is NOT not an example of physical weathering? B. frost wedging B. oxidation C. salt crystal growth D. abrasion 7. Which of these rocks is most likely to be damaged by acid rain? A. Limestone B. Granite C. Gabbro D. Pumice 8. Which of the following is a major factor of the creation of canyons? A. Water B. oxygen C. carbon dioxide _ D. iron 9. What type of rock is made when tiny particles of other rocks settle at the bottom of the bodies of water? A. Igneous B. Sedimentary C. Metamorphic 10. The following are types of chemical weathering EXCEPT for A. abrasion —_B. oxidation C. hydrolysis D. dissolution 11. Which of the following happens during frost wedging? A. Water sips on the cracks of the rocks and then it freezes. B. Water causes the rock to have smooth surface. C. Water breaks the rock into pieces because of its direct impact. D. Water creates cracks into the rocks. 12. Which of the following element causes the rusting of rocks? A. Hydrogen B. calcium C. iron D. oxygen 13. What happens during chemical weathering? A. Components of related rocks react to each other. B. Exposure of rocks to friction from winds exposes it and breaks it down.