Relative and Absolute Dating PDF

RELATIVE AND ABSOLUTE DATING for Earth Science – Senior High School (Core Subject) Quarter 2 / Week 5  FOREWORD Dear students of Senior High School. Welcome back to this week’s self-learning kit where you will journey to the...

RELATIVE AND ABSOLUTE DATING for Earth Science – Senior High School (Core Subject) Quarter 2 / Week 5  FOREWORD Dear students of Senior High School. Welcome back to this week’s self-learning kit where you will journey to the new lesson. This learning kit will serve as a guide in understanding deeply the concepts on stratification and dating of rocks. In this learning kit you will gain knowledge in explaining the stratification or layering of rocks through the deposition, generally of sedimentary rocks. It will also broaden your ideas on the factors which cause the formation of layers of rocks and how rock stratification will be useful in understanding past environments. It will also describe the laws which help in explaining how rocks are formed and changed over time. Activities and post evaluation are included to make learning more fun and exciting. Furthermore, you will be able to know how the age of a fossil is determined and what principles are used to determine the age of a rock and a particular fossil. Hence, this learning kit will be your aid as you embark new scientific words, ideas and enrich your existing knowledge about scientific concepts. The author of this module has been an experienced teacher in the field of Biology and teaching core and applied subjects in the Senior High Curriculum. 2  OBJECTIVES: At the end of this module, you will be able to: 1. Explain how relative and absolute dating are used in determining the age of stratified rocks. 2. Describe different principles used in relative and absolute dating. 3. Value the importance of scientific developments in dating rock materials and discoveries of events both in the past and at present. LEARNING COMPETENCY: Describe the different methods (relative and absolute dating) to determine the age of stratified rocks (S11ES-IIh- i-36). 3 I. WHAT HAPPENED Let’s Warm Up: MATCH THEM UP! Directions. Match the pictures in column A to the items in column B which gives the correct idea by writing the letters only. Identify each item in column B either Relative Dating or Absolute Dating for column C. Write your answers in the notebook. Optional: Visit https://wordwall.net/resource/3277843 and enjoy the activity. 4 II. WHAT I NEED TO KNOW As an ordinary individual, we cannot tell, even hardly guess the age of a rock by looking at it. However, as it was mentioned earlier that geologists and paleontologists could give the ages of the objects or materials they discovered, and time of events that happened in the past considering that they were not present on that particular time of event. And so we ask, how were they able to determine the age of the rocks and fossils in general? Geologists often need to know the age of material that they find. Geologic age dating is assigning an age to materials. There are two types of age determinations. Geologists in the late 18th and early 19th century studied rock layers and the fossils in them to determine relative age. Relative dating is the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages like how many years ago the object was formed. It is like saying that your granny is older than you. The following are the principles in relative dating Stratigraphy is the science of understanding the variations in the successively layered character of rocks and their composition. These rocks may be sedimentary, volcanic, metamorphic or igneous (see Figure 1). Principle of Superposition: Nicolaus Steno, a Danish anatomist, geologist, and priest (1636 - 1686) observed the changes in a sequence of rock layers while working in the mountains of Italy. Steno's observations became known as the Law of Superposition which simply stated that in a sequence of sedimentary rock layers, each layer of rock is older than the layer above it and younger than the rock layer below it (see Figure 2). 5  Source. Source: https://b.kisscc0.com/20180813/xce/kisscc0-law-of- https://www.slideshare.net/gauravhtandon1/stratigraphy superposition-geology-superposition-princip-superposition- 5b71941e55df49.5256776815341701423517.png Figure 1. Layering of rocks as described by Stratigraphy. Figure 2. Layering of rocks from oldest to youngest described by principle of superposition. Principle of Original Horizontality: Layers of rocks deposited from above, such as sediments and lava flows, are originally laid down horizontally. The exception to this principle is at the margins of basins, where the strata can slope slightly downward into the basin (see Figure 3). Principle of Lateral Continuity: Within the depositional basin, strata are continuous in all directions until they thin out at the edge of that basin. Of course, all strata eventually end, either by hitting a geographic barrier, such as a ridge, or when the depositional process extends too far from its source, either a sediment source or a volcano. Strata that are cut by a canyon later remain continuous on either side of the canyon (see Figure 4). Source: Source: https://b.kisscc0.com/20180813/xce/kisscc0-law-of- https://www.bing.com/images/search?q=principle+of superposition-geology-superposition-princip-superposition- +original+horizontality%3a&form=HDRSC3&first=1&sce 5b71941e55df49.5256776815341701423517.png nario=ImageBasicHover Figure 4. Layering of rocks from oldest to youngest Figure 3. Principle of Original horizontality describe by principle of superposition. statesPrinciple that layers ofof Cross- sediments deposited horizontally under action of gravity 6  Cutting Relationships: Deformation events like folds, faults and igneous intrusions that cut across rocks are younger than the rocks they cut across (see Figure 5). Principle of Inclusions: When one rock formation contains pieces or inclusions of another rock, the included rock is older than the host rock (see Figure 6). Source: http://geologikita.blogspot.com/2009/11/prinsip-dasar- Source: https://slideplayer.com/slide/10988275/ geologi-dalam-penentuan.html. Figure 6. Principle of inclusion Figure 5. Principle of cross-cutting relationship Principle of Fossil Succession: Evolution has produced a succession of unique fossils that correlate to the units of the geologic time scale. Assemblages of fossils contained in strata are unique to the time they lived and can be used to correlate rocks of the same age across a wide geographic distribution. Assemblages of fossils refer to groups of several unique fossils occurring together (see Figure 7). Source. https://www.google.com/search?q=index+fossils+table&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiktfGom4HrAh WzJaYKHTHYDwgQ_AUoAXoECA0QAw&biw=1349&bih=603#imgrc=GVKYlALKYRvjFM Figure 7. Principle of Fossil Succession. 7  Relative dating principles was how scientists interpreted Earth history until the end of the 19th Century. Because science advances as technology advances, the discovery of radioactivity in the late 1800s provided scientists with a new scientific tool called radioisotopic dating. Using this new technology, they could assign specific time units, in this case years, to mineral grains within a rock. These numerical values are not dependent on comparisons with other rocks such as with relative dating, so this dating method is called absolute dating. In other words, absolute dating is determining the actual age of an event or object in years. It is like saying, you are 17 years old and your granny is 67 years old. With absolute age dating, you get a real age in actual years. There are several types of absolute dating but let us focus on a few of the common methods here. Absolute dating is based either on fossils which are recognized to represent a particular interval of time, or on radioactive decay of specific isotopes. Scientists often use radioactive isotopes (atoms of the same element that have a different number of neutrons) to find the absolute age of rocks and other materials. Fossils the age of sedimentary rock can be determined using fossils. Sedimentary rock layers and the fossils within them cannot be dated directly. But igneous rock layers on either side of a fossil layer can be dated radiometrically. Once the older and younger rock layers are dated, scientists can assign an absolute age range to the sedimentary rock layer containing the fossils. Index fossils are fossils used to estimate the absolute age of the rock layers in which they are found. Once the absolute age of an index fossil is known, it can be used to determine the age of rock layers containing the same fossil anywhere on Earth. Here are some characteristics of an index fossil: ✓ The organism from which it formed must have lived during a relatively short geologic time span. ✓ It must be relatively common and must be found over a large area. ✓ It must also have features that make them different from other fossils. 8  Table 1: Common Index Fossils Source:https://www.google.com/search?q=index+fossils+images&tbm=isch&ved=2ahUKEwiTm5f-m4HrAhX6zIsBHReCDCsQ2- cCegQIABAA&oq=index+fossils+images&gs_lcp=CgNpbWcQAzIECAAQGDoCCAA6BAgAEB46BggAEAUQHlDSoQRYvr0EYMi- BGgAcAB4AIABdYgBjg2SAQQ0LjEymAEAoAEBqgELZ3dzLXdpei1pbWfAAQE&sclient=img&ei=EygpX9PFJ_qZr7wPl4Sy2AI&bih=603&biw =1349#imgrc=PQuIG6FuycHcvM&imgdii=PL_PDg5a6BEU-M Index fossils act as markers for the time that the organisms were alive on Earth. Index fossils can also be used to date rocks in separate areas. The appearance of the same index fossil in rock of different areas shows that the rock layers formed at about the same time. Radioactive Decay and Half life The absolute age of rock can be determined using radioactive decay. Radioactive isotopes are isotopes that are unstable and break down into other isotopes by a process called radioactive decay (shown in the figure below). The radioactive isotope is called the parent isotope, and the stable isotope formed by its breakdown is called the daughter Source: https://www.google.com/search?q=half+life+geology&tbm=isch&ved=2ahUKEwjU0oCil77qAhVK isotope. bJQKHaD7CdEQ2- cCegQIABAA&oq=half+life+geology&gs_lcp=CgNpbWcQAzICCAAyAggAMgQIABAYMgQIABAY OgQIABBDUKYfWLQwYJI1aABwAHgAgAHhAYgBmwiSAQUwLjcuMZgBAKABAaoBC2d3cy13aXo taW1n&sclient=img&ei=igIGX9TlB8rY0QSg96eIDQ&bih=564&biw=1366#imgrc=717kWcBh3nkU HM&imgdii=DP-ZOv3_bKsFkM Figure 8: Radioactive Decay 9  Half-life is the time needed for half of a sample of a radioactive element to undergo radioactive decay and form daughter isotopes. After one half-life has passed, one-half of the parent isotope has changed into daughter isotopes (shown in table 2 below). Table 2: Isotopes and Half-life of some elements Source:https://www.google.com/search?q=half+life+geology&tbm=isch&ved=2ahUKEwjU0oCil77qAhVKbJQKHaD7CdEQ2- cCegQIABAA&oq=half+life+geology&gs_lcp=CgNpbWcQAzICCAAyAggAMgQIABAYMgQIABAYOgQIABBDUKYfWLQwYJI1aABwAHg AgAHhAYgBmwiSAQUwLjcuMZgBAKABAaoBC2d3cy13aXotaW1n&sclient=img&ei=igIGX9TlB8rY0QSg96eIDQ&bih=564&biw=1366 Finding the absolute age of a sample by determining the relative percentages of a radioactive parent isotope and a stable daughter isotope is called radiometric dating. Igneous rocks are the best types of rock samples to use for radiometric dating. When igneous rocks form, minerals in them often contain only a parent isotope and none of the daughter isotope. Scientists use many different isotopes for radiometric dating. The type of isotope used depends on the type of material being dated. The half-life of the isotope used is also very important. It cannot be too short or too long compared to the age of the sample. Radiocarbon dating is a method used for dating wood, bones, shells, and other organic remains. All living things have a constant ratio of radioactive carbon- 14 to carbon-12. Once a plant or an animal dies, no more carbon is taken in. The ratio between the isotopes changes because carbon-14 undergoes radioactive decay. Radiocarbon dating can be used to date organic matter only. This method is used to date things that lived in the last Source: https://opentextbc.ca/chemistry/chapter/21-3- 45,000 years. radioactive-decay/ Figure 9: Radioactive decay in plants and animals 10  Performance Task Apply the principles in determining the age of the rock using relative dating method. Copy and answer in your notebook. A. Directions: Determine the age of the given layers of the rocks as shown in the Relative Age Rock Diagram below by indicating numbers 1-10 in the empty circles (1 being the bottom layer). B. Directions. Read the guide questions below. Refer to your labeled answers in part A. In accomplishing part B, write the answers in your notebook. 1. What layer number is the first? ____ Color? ______ 2. What layer number is the last? ____ Color? ______ 3. What layer number is the “oldest” in the sequence? _____ Color? ______ 4. What is the overall sequence of events if there was no disturbance (from the oldest to youngest)? Write the number and color sequence. ________________________________________________________________________ ________________________________________________________________________ ________________________________________________ 11 III. WHAT I HAVE LEARNED Part 1. Identification Directions. Study how to determine the relative age of rock diagram below. List the rock layers in order at the bottom of the diagram on the lines provided from most recent at the top to the oldest at the bottom. Answer in your notebook. Source:https://www.sciencelearn.org.nz/resources/1486-absolute- dating#:~:text=Geologists%20often%20need%20to%20know,geological%20events%20in%20time%20order List the rocks from oldest to most recently formed. Most recent rock formed: _______________________ _______________________ _______________________ _______________________ _______________________ _______________________ Oldest rock: _______________________ Part 2. Short answer. Directions. Write your own understanding in 3-4 sentences of the following terms. You will be rated using the rubric provided. 1. Absolute dating 2. Principle of Superposition 3. Radiocarbon dating 4. Index fossils 5. Principle of Original Horizontality 6. 12 Rubrics: 4 3 2 1 Presented an idea but Presented a strong Presented a may not reflect Does not present an understanding of the understanding of the understanding of the idea of the topic topic topic topic The errors in punctuation, Spelling and Spelling and There are many errors in capitalization and punctuation are all punctuation are mostly spelling, capitalization spelling disrupt correct correct and punctuation understanding of the topic 13 REFERENCES Absolute dating. Retrieved June 30, 2020 from https://geo.libretexts.org/Bookshelves/Geology/Book%3A_An_Introductio n_to_Geology_(Johnson%2C_Affolter%2C_Inkenbrandt%2C_and_Mosher) /07%3A_Geologic_Time/7.02%3A_Absolute_Dating Absolute dating. Retrieved July 1, 2020 from https://www.sciencelearn.org.nz/resources/1486-absolute- dating#:~:text=Geologists%20often%20need%20to%20know,geological% 20events%20in%20time%20order Common Isotope pairs chart. Retrieved July 2, 2020 from https://www.google.com/search?q=half+life+geology&tbm=isch&ved=2 ahUKEwjU0oCil77qAhVKbJQKHaD7CdEQ2- cCegQIABAA&oq=half+life+geology&gs_lcp=CgNpbWcQAzICCAAyAgg AMgQIABAYMgQIABAYOgQIABBDUKYfWLQwYJI1aABwAHgAgAHhAYgB mwiSAQUwLjcuMZgBAKABAaoBC2d3cy13aXotaW1n&sclient=img&ei=igI GX9TlB8rY0QSg96eIDQ&bih=564&biw=1366#imgrc=717kWcBh3nkUHM&im gdii=DP-ZOv3_bKsFkM Dating fossils- how are fossils dated? Retrieved July 2, 2020 from https://www.fossilera.com/pages/dating- fossils#:~:text=Absolute%20Dating- ,Absolute%20dating%20is%20used%20to%20determine%20a%20precise%2 0age%20of,rocks%20they%20are%20found%20in. Geologic dating explained. Retrieved June 30, 2020 from https://www.kidsdiscover.com/teacherresources/geologic-age-dating- explained/ Index Fossils illustration. Retrieved July 6,2020 from https://www.google.com/search?q=index+fossils+images&tbm=isch&ved =2ahUKEwiTm5f-m4HrAhX6zIsBHReCDCsQ2- cCegQIABAA&oq=index+fossils+images&gs_lcp=CgNpbWcQAzIECAAQ GDoCCAA6BAgAEB46BggAEAUQHlDSoQRYvr0EYMi- BGgAcAB4AIABdYgBjg2SAQQ0LjEymAEAoAEBqgELZ3dzLXdpei1pbWfAA QE&sclient=img&ei=EygpX9PFJ_qZr7wPl4Sy2AI&bih=603&biw=1349#imgrc =PQuIG6FuycHcvM&imgdii=PL_PDg5a6BEU-M Introduction Stratigraphy. Retrieved July 6, 2020 from http://www.sepmstrata.org/page.aspx?pageid=15#:~:text=Stratigraphy% 20is%20the%20science%20of,%2C%20volcanic%2C%20metamorphic%20o r%20igneous. Law of cross-cutting relationships image. Retrieved July 6, 2020 from https://imnh.iri.isu.edu/exhibits/online/geo_time/geo_principles.htm 14 Principle of inclusion image. Retrieved July 7, 2020 from https://www.google.com/search?q=principle+of+inclusion+geology&tb m=isch&ved=2ahUKEwjg8MSonb3qAhWGAaYKHdEBCOQQ2- cCegQIABAA&oq=principle+of+inclusion&gs_lcp=CgNpbWcQARgBMgII ADICCAAyAggAMgIIADICCAAyAggAMgIIADICCAAyAggAMgIIADoECA AQQzoFCAAQsQNQjqeTCliw35MKYIP0kwpoAHAAeASAAYcDiAH9HZIBCD AuMjQuMi4xmAEAoAEBqgELZ3dzLXdpei1pbWewAQA&sclient=img&ei=q oIFX-DzKoaDmAXRg6CgDg&bih=613&biw=1366#imgrc=jhYXBRL4SOjCAM Principles of Geology. Retrieved July 6, 2020 from https://timescavengers.blog/introductory-material/geologic- time/principles-of-geology/ Principle of Succession illustration. Retrieved July 7, 2020 from https://www.google.com/search?q=index+fossils+table&source=lnms&tb m=isch&sa=X&ved=2ahUKEwiktfGom4HrAhWzJaYKHTHYDwgQ_AUoAXoE CA0QAw&biw=1349&bih=603#imgrc=GVKYlALKYRvjFM Radioactive decay and half-life table. Retrieved July 6, 2020 from https://www.google.com/search?q=half+life+geology&tbm=isch&ved=2 ahUKEwjU0oCil77qAhVKbJQKHaD7CdEQ2- cCegQIABAA&oq=half+life+geology&gs_lcp=CgNpbWcQAzICCAAyAgg AMgQIABAYMgQIABAYOgQIABBDUKYfWLQwYJI1aABwAHgAgAHhAYgB mwiSAQUwLjcuMZgBAKABAaoBC2d3cy13aXotaW1n&sclient=img&ei=igI GX9TlB8rY0QSg96eIDQ&bih=564&biw=1366 Radiocarbon dating illustration. Retrieved July 6, 2020 from https://chem.libretexts.org/Courses/Furman_University/CHM101%3A_Che mistry_and_Global_Awareness_(Gordon)/05%3A_Basics_of_Nuclear_Scie nce/5.07%3A_Calculating_Half-Life Relative and absolute dating. Retrieved June 29, 2020 from https://opentextbc.ca/chemistry/chapter/21-3-radioactive-decay/ Relative and absolute dating. Retrieved June 29, 2020 https://geo.libretexts.org/Bookshelves/Geology/Book%3A_An_Introductio n_to_Geology_(Johnson%2C_Affolter%2C_Inkenbrandt%2C_and_Mosher) /07%3A_Geologic_Time/7.01%3A_Relative_Dating#3 Steno’s Law of Stratigraphy illustration. Retrieved July 6, 2020 from https://kids.britannica.com/students/assembly/view/199325 Stratigraphy image. Retrieved July 6, 2020 from https://www.google.com/search?q=stratigraphy&tbm=isch&ved=2ahUK Ewjb9ZHjnL3qAhWHzYsBHex7C1cQ2- cCegQIABAA&oq=stratigraphy&gs_lcp=CgNpbWcQAzICCAAyAggAMgII ADICCAAyAggAMgIIADICCAAyAggAMgIIADICCAA6BggAEAcQHjoGCA 15  AQChAYUPLUCFjV1whgkt8IaABwAHgAgAF8iAHkApIBAzAuM5gBAKABAa oBC2d3cy13aXotaW1n&sclient=img&ei=GYIFX5uFCoebr7wP7PetuAU&bih =613&biw=1366#imgrc=LVaHiLC6Ymp5DM Stratigraphy image. Retrieved July 7, 2020 from https://www.google.com/search?q=stratigraphy&tbm=isch&ved=2ahUK Ewjb9ZHjnL3qAhWHzYsBHex7C1cQ2cCegQIABAA&oq=stratigraphy&gs_lc p=CgNpbWcQAzICCAAyAggAMgIIADICCAAyAggAMgIIADICCAAyAgg AMgIIADICCAA6BggAEAcQHjoGCAAQChAYUPLUCFjV1whgkt8IaABwAH gAgAF8iAHkApIBAzAuM5gBAKABAaoBC2d3cy13aXotaW1n&sclient=img &ei=GYIFX5uFCoebr7wP7PetuAU&bih=613&biw=1366#imgrc=l9YnnfU4mT _dTM&imgdii=FcQpxnmUmfDdZM The Law of Superposition image. Retrieved July 7, 2020 from https://www.google.com/search?q=stratigraphy&tbm=isch&ved=2ahUK Ewjb9ZHjnL3qAhWHzYsBHex7C1cQ2cCegQIABAA&oq=stratigraphy&gs_lc p=CgNpbWcQAzICCAAyAggAMgIIADICCAAyAggAMgIIADICCAAyAgg AMgIIADICCAA6BggAEAcQHjoGCAAQChAYUPLUCFjV1whgkt8IaABwAH gAgAF8iAHkApIBAzAuM5gBAKABAaoBC2d3cy13aXotaW1n&sclient=img &ei=GYIFX5uFCoebr7wP7PetuAU&bih=613&biw=1366#imgrc=l9YnnfU4mT _dTM&imgdii=FcQpxnmUmfDdZM 16  ACKNOWLEDGMENT Division of Negros Oriental SENEN PRISCILLO P. PAULIN, CESO V Schools Division Superintendent FAY C. LUAREZ, TM, EDD, PHD OIC-Assistant Schools Division Superintendent Acting CID Chief NILITA L. RAGAY, EDD OIC-Assistant Schools Division Superintendent ROSELA R. ABIERA Education Program Supervisor – (LRMDS) ARNOLD R. JUNGCO PSDS – Division Science Coordinator MARICEL S. RASID Librarian II (LRMDS) ELMER L. CABRERA PDO II (LRMDS) BERNADETTE NOVEM I. SARDON Writer NOELYN E. SIAPNO Lay-out Artist _____________ ALPHA QA TEAM LIEZEL A. AGOR MARY JOYCEN A. ALAM-ALAM EUFRATES G. ANSOK JR. JOAN Y. BUBULI LIELIN A. DE LA ZERNA THOMAS JOGIE U. TOLEDO BETA QA TEAM JOAN Y. BUBULI LIELIN A. DE LA ZERNA MIEL C. PACULANANG ARJIE T. PALUMPA DISCLAIMER The information, activities and assessments used in this material are designed to provide accessible learning modality to the teachers and learners of the Division of Negros Oriental. The contents of this module are carefully researched, chosen, and evaluated to comply with the set learning competencies. The writers and evaluator were clearly instructed to give credits to information and illustrations used to substantiate this material. All content is subject to copyright and may not be reproduced in any form without expressed written consent from the division. 17 SYNOPSIS Geologic age dating is assigning an age to rocks and other organic materials. There are two types of age determinations- relative and absolute dating. Relative dating is the process of determining if one rock or geologic event is older or younger than another, without knowing their specific ages. While absolute dating is determining the actual age of an event or object in years. There are guiding principles in determining the age of rocks in relative dating. These are the law of superposition, original horizontality, cross-cutting relationships, lateral continuity, inclusions of rocks and fossil succession. Some of the methods also used are absolute dating- radioactive decay, index fossils, determining half- life, and the commonly used carbon dating. ABOUT THE AUTHOR BERNADETTE NOVEM I. SARDON is a licensed Professional Teacher. She is a graduate of University of San Carlos with the degree of Bachelor of Science in Biology. She is currently teaching at San Miguel National High School as a Senior High teacher, at the same time the Teacher-in-Charge of the same school. She has earned units in Masters in Biology and Master of Education major in Guidance and Psychology. 18