1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu How to Use This Presentation To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. You may exit the slide show at any time by pressing the Esc key.

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chapter Presentation Transparencies Image and Math Focus Bank Bellringers Standardized Test Prep Visual Concepts Resources

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Rock and Fossil Record Table of Contents Section 1 Earth’s Story and Those Who First Listened Section 2 Relative Dating: Which Came First? Section 3 Absolute Dating: A Measure of Time Section 4 Looking at Fossils Section 5 Time Marches On Chapter F3

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Earth’s Story and Those Who First Listened Bellringer “The Present Is the Key to the Past.” This phrase was the cornerstone of the uniformitarianist theory developed by geologist James Hutton in the late 1700s. Write a few sentences in your science journal about how studying the present could reveal the story of Earth’s history. Use sketches to illustrate processes that occurred millions of years ago that you can still see today. Chapter F3

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Compare uniformitarianism and catastrophism. Describe how the science of geology has changed over the past 200 years. Explain the role of paleontology in the study of Earth’s history. Section 1 Earth’s Story and Those Who First Listened Chapter F3

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Uniformitarianism Scientist James Hutton, the author of Theory of the Earth, proposed that geologic processes such as erosion and deposition do not change over time. Uniformitarianism is the idea that the same geologic processes shaping the Earth today have been at work throughout Earth’s history. The next slide shows how Hutton developed the idea of uniformitarianism. Section 1 Earth’s Story and Those Who First Listened Chapter F3

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Earth’s Story and Those Who First Listened Chapter F3

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Uniformitarianism, continued Uniformitarianism Versus Catastrophism Hutton’s theories sparked a scientific debate by suggesting the Earth was much older than a few thousand years, as previously thought. A few thousand years was not enough time for the gradual geologic processes that Hutton described to have shaped the planet. Section 1 Earth’s Story and Those Who First Listened Chapter F3

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Uniformitarianism, continued A Victory for Uniformitarianism Catastrophism was geology’s guiding principle until the work of geologist Charles Lyell caused people to reconsider uniformitarianism. Lyell published Principles of Geology in the early 1830s. Armed with Hutton’s notes and new evidence of his own, Lyell successfully challenged the principle of catastrophism. Section 1 Earth’s Story and Those Who First Listened Chapter F3

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Modern Geology -- A Happy Medium During the late 20th century, scientists such as Stephen J. Gould challenged Lyell’s uniformitarianism. They believed that catastrophes occasionally play an important role in shaping Earth’s history. Today, scientists realize that most geologic change is gradual and uniform, but catastrophes that cause geologic change have occurred during Earth’s long history. Section 1 Earth’s Story and Those Who First Listened Chapter F3

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Uniformitarianism and Catastrophism Section 1 Earth’s Story and Those Who First Listened Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept Chapter F3

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Paleontology -- The Study of Past Life The history of the Earth would be incomplete without knowledge of the organisms that have inhabited our planet and the conditions under which they lived. The science involved with the study of past life is called paleontology. Paleontologist study fossils, which are the remains of organisms preserved by geologic processes. Section 1 Earth’s Story and Those Who First Listened Chapter F3

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Relative Dating: Which Came First? Bellringer Arrange the following sentences in a logical order to make a short story: I stood in the checkout line. I selected two apples. I walked home from the store. I gave the cashier money. I went to the store. The cashier gave me change. I was hungry. Write your story in your science journal. Chapter F3

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Explain how relative dating is used in geology. Explain the principle of superposition. Describe how the geologic column is used in relative dating. Identify two events and two features that disrupt rock layers. Explain how physical features are used to determine relative ages. Section 2 Relative Dating: Which Came First? Chapter F3

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Superposition Geologists try to determine the order in which events have happened during Earth’s history. They rely on rocks and fossils to help them in their investigation. The process of determining whether an event or object is older or younger than other events or objects is called relative dating. Section 2 Relative Dating: Which Came First? Chapter F3

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Superposition, continued Layers of sedimentary rock, such as the ones shown below, are stacked like pancakes. Section 2 Relative Dating: Which Came First? Chapter F3

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Superposition, continued As you move from the top to the bottom in layers of sedimentary rock, the lower layers are older. Superposition is a principle that states that younger rocks lie above older rocks, if the layers have not been disturbed. Section 2 Relative Dating: Which Came First? Chapter F3

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Principle of Superposition, continued Disturbing Forces Not all rock sequences are arranged with the oldest layers on the bottom and the youngest layers on top. Some rock sequences have been disturbed by forces within the Earth. These forces can push other rocks into a sequence, tilt or fold rock layers, and break sequences into moveable parts. Section 2 Relative Dating: Which Came First? Chapter F3

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Column The geologic column is an ideal sequence of rock layers that contains all the known fossils and rock formations on Earth, arranged from oldest to youngest. Geologists use the geologic column to interpret rock sequences and to identify the layers in puzzling rock sequences. Section 2 Relative Dating: Which Came First? Chapter F3

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Geologic Column Section 2 Relative Dating: Which Came First? Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept Chapter F3

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Disturbed Rock Layers Geologists often find features that cut across existing layers of rock. Geologists use the relationships between rock layers and the features that cross them to assign relative ages to the features and the layers. The features must be younger than the rock layers because the rock layers had to be present before the features could cut across them. Section 2 Relative Dating: Which Came First? Chapter F3

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Disturbed Rock Layers, continued Events That Disturb Rock Layers Geologists assume that the way sediment is deposited to form rock layers — in horizontal layers — has not changed over time. If rock layers are not horizontal, something must have disturbed them after they formed. The next slide describes four ways that rock layers may become disturbed. Section 2 Relative Dating: Which Came First? Chapter F3

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Disturbed Rock Layers, continued A fault is a break in the Earth’s crust along which blocks of the crust slide relative to one another. An intrusion is molten rock from the Earth’s interior that squeezes into existing rock and cools. Folding occurs when rock layers bend and buckle from Earth’s internal forces. Tilting occurs when internal forces in the Earth slant rock layers. Section 2 Relative Dating: Which Came First? Chapter F3

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Gaps in the Record -- Unconformities Missing Evidence Sometimes, layers of rock are missing, creating a gap in the geologic record. Missing rock layers create breaks in rock-layer sequences called unconformities. An unconformity is a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time. Section 2 Relative Dating: Which Came First? Chapter F3

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Unconformities Section 2 Relative Dating: Which Came First? Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept Chapter F3

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Unconformities Most unconformities form by both erosion and nondeposition, but other factors may be involved. To simplify the study of unconformities, geologists place them into three major categories: disconformities, nonconformities, and angular unconformities. Section 2 Relative Dating: Which Came First? Chapter F3

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Unconformities, continued Disconformities exist where part of a sequence of parallel rock layers is missing. Section 2 Relative Dating: Which Came First? Chapter F3

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Unconformities, continued Nonconformities exist where sedimentary rock layers lie on top of an eroded surface of nonlayered igneous or metamorphic rock. Section 2 Relative Dating: Which Came First? Chapter F3

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Unconformities, continued Angular Unconformities exist between horizontal rock layers and rock layers that are tilted or folded. Section 2 Relative Dating: Which Came First? Chapter F3

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Rock-Layer Puzzles Rock-layer sequences often have been affected by more than one geological event or feature. Section 2 Relative Dating: Which Came First? For example, intrusions may squeeze into rock layers that contain an unconformity, as shown at right. Chapter F3

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Rock-Layer Puzzles, continued Determining the order events that led to a sequence that has been disturbed by more than one rock- disturbing feature is like solving a jigsaw puzzle. Geologists must use their knowledge of the events that disturb rock-layer sequences to piece together the history of the Earth. Section 2 Relative Dating: Which Came First? Chapter F3

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Absolute Dating: A Measure of Time Bellringer Do the following statements describe relative or absolute age? 1. She is my younger sister. 2. He is 12 years old. Why do geologists use both absolute and relative dating to interpret the past? Why are both absolute and relative dates valid dates for geologists, and other earth scientists to use? Write a paragraph in your science journal. Chapter F3

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Describe how radioactive decay occurs. Explain how radioactive decay relates to radiometric dating. Identify four types of radiometric dating. Determine the best type of radiometric dating to use to date an object. Section 3 Absolute Dating: A Measure of Time Chapter F3

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radioactive Decay Absolute dating is any method of measuring the age of an event or object in years. To determine the absolute ages of fossils and rocks, scientists analyze isotopes of radioactive elements. Atoms of the same element that have the same number of protons but different numbers of neutrons are called isotopes. Section 3 Absolute Dating: A Measure of Time Chapter F3

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radioactive Decay, continued Most isotopes are stable, meaning that they stay in their original form. Other isotopes are unstable. Scientists call unstable isotopes radioactive. Section 3 Absolute Dating: A Measure of Time Chapter F3

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radioactive Decay, continued Radioactive isotopes tend to break down into stable isotopes of the same or other elements in a process called radioactive decay. Section 3 Absolute Dating: A Measure of Time Chapter F3

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radioactive Decay, continued Because radioactive decay occurs at a steady rate, scientists can use the relative amounts of stable and unstable isotopes present in an object to determine the object’s age. Section 3 Absolute Dating: A Measure of Time Chapter F3

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radioactive Decay, continued Dating Rocks — How Does It Work? In radioactive decay, an unstable radioactive isotope of one element breaks down into a stable isotope. The stable isotope may be of the same element or of a different element. The unstable radioactive isotope is called the parent isotope. The stable isotope produced by the radioactive decay of the parent isotope is called the daughter isotope. Section 3 Absolute Dating: A Measure of Time Chapter F3

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radioactive Decay, continued The rate of radioactive decay is constant, so scientists can compare the amount of parent material with the amount of daughter material to date rock. The more daughter material there is, the older the rock is. Section 3 Absolute Dating: A Measure of Time Chapter F3

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radiometric Dating Determining the absolute age of a sample, based on the ratio of parent material to daughter material is called radiometric dating. If you know the rate of decay for a radioactive element in a rock, you can figure out the absolute age of the rock. Section 3 Absolute Dating: A Measure of Time Chapter F3

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radiometric Dating, continued A half-life is the time needed for half of a sample of a radioactive substance to undergo radioactive decay. After every half-life, the amount of parent material decrease by one-half. Section 3 Absolute Dating: A Measure of Time Chapter F3

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Radiometric Dating Scientists use different radiometric-dating methods based on the estimated age of an object. There are four radiometric-dating techniques. Potassium-Argon Method Potassium-40 has a half- life of 1.3 billion years, and it decays leaving a daughter material of argon. This method is used mainly to date rocks older than 100,000 years. Section 3 Absolute Dating: A Measure of Time Chapter F3

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Radiometric Dating, continued Uranium-Lead Method Uranium-238 is a radioactive isotope with a half-life of 4.5 billion years. Uranium-238 decays in a series of steps to lead-206. The uranium-lead method can be used to date rocks more than 10 million years old. Section 3 Absolute Dating: A Measure of Time Chapter F3

44. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Radiometric Dating, continued Rubidium-Strontium Method The unstable parent isotope rubidium-87 forms a stable daughter isotope strontium-87. The half-life of rubidium-87 is 49 billion years. This method is used for rocks older than 10 million years. Section 3 Absolute Dating: A Measure of Time Chapter F3

45. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Radiometric Dating, continued Carbon-14 Method Carbon is normally found in three forms, the stable isotopes carbon-12 and carbon-13, and the radioactive isotope carbon-14. Living plants and animals contain a constant ratio of carbon-14 to carbon-12. Once a plant or animal dies, no new carbon is taken in. The amount of carbon-14 begins to decrease as the plant or animal decays. Section 3 Absolute Dating: A Measure of Time Chapter F3

46. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Radiometric Dating, continued The half-life of carbon-14 is 5,730 years. The carbon-14 method of radiometric dating is used mainly for dating things that lived within the last 50,000 years. Section 3 Absolute Dating: A Measure of Time Chapter F3

47. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Radiometric Dating Section 3 Absolute Dating: A Measure of Time Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept Chapter F3

48. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer Describe the fossil record of your own life that might be found 65 million years from now. What items, or artifacts, might be likely to survive? What kinds of things would decay and disappear? Do you think your fossil record would produce an accurate picture of your life? What might be missing? Write your description in your science journal. Section 4 Looking at Fossils Chapter F3

49. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Describe five ways that different types of fossils form. List three types of fossils that are not part of organisms. Explain how fossils can be used to determine the history of changes in environments and organisms. Explain how index fossils can be used to date rock layers. Section 4 Looking at Fossils Chapter F3

50. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fossilized Organisms The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock is called a fossil. Fossils are most often preserved in sedimentary rock, but other materials can also preserve evidence of past life. Section 4 Looking at Fossils Chapter F3

51. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fossilized Organisms, continued Fossils in Rocks When an organism dies, it either begins to decay or is consumed by other organisms. Sometimes dead organisms are quickly buried by sediment, which slows down decay. Shells and bones are more resistant to decay than soft tissues, so when sediments become rock, the harder structures are more commonly preserved. Section 4 Looking at Fossils Chapter F3

52. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fossilized Organisms, continued Fossils in Amber Organisms occasionally become trapped in soft, sticky tree sap, which hardens and becomes amber. Insect fossils have often been preserved in this way, but frogs and lizards have also been found in amber. Section 4 Looking at Fossils Chapter F3

53. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fossilized Organisms, continued Petrifaction is a process in which minerals replace and organism’s tissues. One form of petrifaction is called permineralization, a process in which the pore space in an organism’s hard tissue is filled up with mineral. Replacement is a process in which an organism’s tissues are completely replaced by minerals. Section 4 Looking at Fossils Chapter F3

54. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fossilized Organisms, continued Fossils in Asphalt There are places where asphalt wells up at the Earth’s surface. These thick, sticky pools can trap and preserve organisms. Frozen Fossils Since cold temperatures slow down decay, many types of fossils have been found preserved in ice. Section 4 Looking at Fossils Chapter F3

55. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Other Types of Fossils Trace Fossils are naturally preserved evidence of animal activity. Preserved animal tracks are an example of a trace fossil. Other types of trace fossils include preserved burrows or shelters that were made by animals, and coprolite, which is preserved animal dung. Section 4 Looking at Fossils Chapter F3

56. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Other Types of Fossils, continued Molds and Casts are two more examples of fossils. A mold is a mark or cavity made in a sedimentary surface by a shell or other body. A cast is a type of fossil that forms when sediments fill the cavity left by a decomposed organism. Section 4 Looking at Fossils Chapter F3

57. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Using Fossils to Interpret the Past The Information in the Fossil Record The fossil record offers only a rough sketch of the history of life on Earth. The fossil record is incomplete because most organisms never became fossils. Scientists know more information about organisms that had hard body parts and that lived in environments that favored fossilization. Section 4 Looking at Fossils Chapter F3

58. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Using Fossils to Interpret the Past, continued History of Environmental Changes The fossil record reveals changes in an area’s climate over time. By using the fossils of plants and land animals, scientists can reconstruct past climates. History of Changing Organisms By studying the relationships between fossils, scientists can interpret how life has changed over time. Section 4 Looking at Fossils Chapter F3

59. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Using Fossils to Date Rocks Scientists have learned that particular types of fossils appear only in certain layers of rock. By dating the rock layers above and below these fossils, scientists can determine the time span in which the organisms that formed the fossils lived. Section 4 Looking at Fossils Chapter F3

60. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Using Fossils to Date Rocks, continued If a type of organism existed for only a short period of time, its fossils would show up in a limited range of rock layers. These fossils are called index fossils. Index fossils are fossils that are found in the rock layers of only one geologic age, and can be used to establish the age of the rock layers. Section 4 Looking at Fossils Chapter F3

61. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Using Fossils to Date Rocks, continued Ammonites An example of an index fossil is the fossil of a genus of ammonites called Tropites. Tropites, a marine mollusk similar to a modern squid, lived between 230 million and 208 million years ago. Section 4 Looking at Fossils Chapter F3

62. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Using Fossils to Date Rocks, continued Trilobites Fossils of a genus of trilobites called Phacops are another example of an index fossil. Trilobites are extinct and lived approximately 400 million years ago. When scientists find Phacops in a rock, they assume that the rock is approximately 400 million years old. Section 4 Looking at Fossils Chapter F3

63. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bellringer Archaeologists and paleontologists believe that modern humans have lived on Earth for 150,000 to 200,000 years. If we imagine the history of Earth to be the length of one calendar year, on which date do you think modern humans arrived? Record your answer in your science journal. Section 5 Time Marches On Chapter F3

64. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Objectives Explain how geologic time is recorded in rock layers. Identify important dates on the geologic time scale. Explain how changes in climate resulted in the extinction of some species. Section 5 Time Marches On Chapter F3

65. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Geologic Time The Rock Record and Geologic Time Grand Canyon National Park is one of the best places in North America to see Earth’s history recorded in rock layers. These rock layers represent almost half, or nearly 2 billion years, of Earth’s history. Section 5 Time Marches On Chapter F3

66. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Geologic Time, continued The Fossil Record and Geologic Time Fossils of plants and animals are common in sedimentary rocks that belong to the Green River formation. These fossils are well preserved. Burial in the fine- grained lake-bed sediments preserved even the most delicate structures. Section 5 Time Marches On Chapter F3

67. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale The geologic column represents the 4.6 billion years that have passed since the first rocks formed on the Earth. To aid in their study, geologists have created the geologic time scale. The geologic time scale is the standard method used to divide the Earth’s long natural history into manageable parts. Section 5 Time Marches On Chapter F3

68. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 5 Time Marches On Chapter F3

69. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued Divisions of Time Geologists have divided the Earth’s history into sections of time. An eon is the largest division of geologic time. The four eons are the Hadean eon, the Archean eon, the Proterozoic eon, and the Phanerozoic eon. Section 5 Time Marches On Chapter F3

70. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued Eons are divided into eras. For example, the Phanerozoic Eon is divided into three eras. Periods are the third-largest divisions of geologic time and are the units into which eras are divided. Periods are divided into epochs, the fourth-largest division of geologic time. Section 5 Time Marches On Chapter F3

71. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued The Appearance and Disappearance of Species At certain times during Earth’s history, the number of species has increased or decreased dramatically. An increase or decrease in the number of species often comes as a result of a relatively sudden increase or decrease in competition among species. Section 5 Time Marches On Chapter F3

72. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued The number of species decreases dramatically over a relatively short period of time during a mass extinction event. Extinction is the death of every member of a species. Events such as global climate change can cause mass extinctions. Section 5 Time Marches On Chapter F3

73. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued The Paleozoic Era — Old Life This era lasted from about 542 million to 251 million years ago. It is the first era that is well represented by fossils. Marine life flourished at the beginning of the era and the oceans became home to a diversity of life. However, there were few land organisms. By the middle of the Paleozoic era, most modern groups of land plants had appeared. Section 5 Time Marches On Chapter F3

74. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued By the end of the Paleozoic era, amphibians and reptiles lived on the land, and insects were abundant. The era came to an end with the largest mass extinction in Earth’s history. Some scientists believe that changes in seawater circulation were a likely cause of this extinction, which killed nearly 90% of all marine species. Section 5 Time Marches On Chapter F3

75. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued The Mesozoic Era — The Age of Reptiles This era began about 251 million years ago. During this era, reptiles, such as dinosaurs, dominated the land. Small mammals appeared about the same time as dinosaurs, and birds evolved late in the era. At the end of the Mesozoic era, about 15% to 20% of all species on Earth, including the dinosaurs, became extinct. Global climate change may have been the cause. Section 5 Time Marches On Chapter F3

76. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Geologic Time Scale, continued The Cenozoic Era — The Age of Mammals The Cenozoic era began about 65.5 million years ago and continues to the present. This era is known as the “Age of Mammals.” After the mass extinction at the end of the Mesozoic era, mammals flourished. Mammals were able to survive the environmental changes that probably caused the extinction of the dinosaurs. Section 5 Time Marches On Chapter F3

77. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Concept Map The Rock and Fossil Record Use the terms below to complete the concept map on the next slide. sedimentary rocks fossils half-life radioactive isotope absolute dating faults Chapter F3

78. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Rock and Fossil Record Chapter F3

79. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu The Rock and Fossil Record Chapter F3

80. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu End of Chapter F3 Show

81. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Reading Read each of the passages. Then answer the questions that follow each passage. Standardized Test Preparation Chapter F3

82. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Passage 1 Three hundred million years ago, the region that is now Illinois had a different climate than it does today. Swamps and shallow bays covered much of the area. No fewer than 500 species of plants and animals lived in this environment. Today, the remains of these organisms are found beautifully preserved within nodules. Continued on the next slide Standardized Test Preparation Chapter F3

83. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Passage 1, continued Nodules are round or oblong structures usually composed of cemented sediments that sometimes contain the fossilized hard parts of plants and animals. The Illinois nodules are exceptional because the soft parts of organisms are found together with hard parts. For this reason, these nodules are found in fossil collections around the world. Standardized Test Preparation Chapter F3

84. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. In the passage, what is the meaning of the word exceptional? A beautiful B extraordinary C average D large Standardized Test Preparation Chapter F3

85. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. In the passage, what is the meaning of the word exceptional? A beautiful B extraordinary C average D large Standardized Test Preparation Chapter F3

86. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. According to the passage, which of the following statements about nodules is correct? F Nodules are rarely round or oblong. G Nodules are usually composed of cemented sediment. H Nodules are not found in present-day Illinois. I Nodules always contain fossils. Standardized Test Preparation Chapter F3

87. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. According to the passage, which of the following statements about nodules is correct? F Nodules are rarely round or oblong. G Nodules are usually composed of cemented sediment. H Nodules are not found in present-day Illinois. I Nodules always contain fossils. Standardized Test Preparation Chapter F3

88. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Which of the following is a fact in the passage? A The Illinois nodules are not well known outside of Illinois. B Illinois has had the same climate throughout Earth’s history. C Both the hard and soft parts of organisms are preserved in the Illinois nodules. D Fewer than 500 species of plants and animals have been found in Illinois nodules. Standardized Test Preparation Chapter F3

89. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Which of the following is a fact in the passage? A The Illinois nodules are not well known outside of Illinois. B Illinois has had the same climate throughout Earth’s history. C Both the hard and soft parts of organisms are preserved in the Illinois nodules. D Fewer than 500 species of plants and animals have been found in Illinois nodules. Standardized Test Preparation Chapter F3

90. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Passage 2 In 1995, paleontologist Paul Sereno and his team were working in an unexplored region of Morocco when they made an astounding find — an enormous dinosaur skull! The skull measured approximately 1.6 m in length, which is about the height of a refrigerator. Given the size of the skull, Sereno concluded that the skeleton of the animal it came from must have been about 14 m long — about as big as a school bus. Continued on the next slide Standardized Test Preparation Chapter F3

91. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Passage 2, continued The dinosaur was even larger than Tyrannosaurus rex! The newly discovered 90 million-year-old predator most likely chased other dinosaurs by running on large, powerful hind legs, and its bladelike teeth meant certain death for its prey. Standardized Test Preparation Chapter F3

92. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. In the passage, what does the word astounding mean? A important B new C incredible D one of a kind Standardized Test Preparation Chapter F3

93. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. In the passage, what does the word astounding mean? A important B new C incredible D one of a kind Standardized Test Preparation Chapter F3

94. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. Which of the following is evidence that the dinosaur described in the passage was a predator? F It had bladelike teeth. G It had a large skeleton. H It was found with the bones of a smaller animal nearby. I It is 90 million years old. Standardized Test Preparation Chapter F3

95. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. Which of the following is evidence that the dinosaur described in the passage was a predator? F It had bladelike teeth. G It had a large skeleton. H It was found with the bones of a smaller animal nearby. I It is 90 million years old. Standardized Test Preparation Chapter F3

96. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. What types of information do you think that fossil teeth provide about an organism? A the color of its skin B the types of food it ate C the speed that it ran D the mating habits it had Standardized Test Preparation Chapter F3

97. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. What types of information do you think that fossil teeth provide about an organism? A the color of its skin B the types of food it ate C the speed that it ran D the mating habits it had Standardized Test Preparation Chapter F3

98. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Interpreting Graphics Use the graph below to answer the questions that follow. Standardized Test Preparation Chapter F3

99. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. At which point in Earth’s history did the greatest mass-extinction event take place? A at point 1, the Ordovician-Silurian boundary B at point 3, the Permian-Triassic boundary C at point 4, the Triassic-Jurassic boundary D at point 5, the Cretaceous-Tertiary boundary Standardized Test Preparation Chapter F3

100. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. At which point in Earth’s history did the greatest mass-extinction event take place? A at point 1, the Ordovician-Silurian boundary B at point 3, the Permian-Triassic boundary C at point 4, the Triassic-Jurassic boundary D at point 5, the Cretaceous-Tertiary boundary Standardized Test Preparation Chapter F3

101. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. Immediately following the Cretaceous-Tertiary extinction, represented by point 5, approximately how many families of marine organisms remained in the Earth’s oceans? F 200 marine families G 300 marine families H 500 marine families I 700 marine families Standardized Test Preparation Chapter F3

102. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. Immediately following the Cretaceous-Tertiary extinction, represented by point 5, approximately how many families of marine organisms remained in the Earth’s oceans? F 200 marine families G 300 marine families H 500 marine families I 700 marine families Standardized Test Preparation Chapter F3

103. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Approximately how many million years ago did the Ordovician-Silurian mass-extinction event, represented by point 1, take place? A 200 million years ago B 250 million years ago C 350 million years ago D 420 million years ago Standardized Test Preparation Chapter F3

104. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. Approximately how many million years ago did the Ordovician-Silurian mass-extinction event, represented by point 1, take place? A 200 million years ago B 250 million years ago C 350 million years ago D 420 million years ago Standardized Test Preparation Chapter F3

105. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Math Read each question and choose the best answer. Standardized Test Preparation Chapter F3

106. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. Carbon-14 is a radioactive isotope with a half-life of 5,730 years. How much carbon-14 would remain in a sample that is 11,460 years old? A 12.5% B 25% C 50% D 100% Standardized Test Preparation Chapter F3

107. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. Carbon-14 is a radioactive isotope with a half-life of 5,730 years. How much carbon-14 would remain in a sample that is 11,460 years old? A 12.5% B 25% C 50% D 100% Standardized Test Preparation Chapter F3

108. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. If a sample contains an isotope with a half-life of 10,000 years, how old would the sample be if 1/8 of the original isotope remained in the sample? F 20,000 years G 30,000 years H 40,000 years I 50,000 years Standardized Test Preparation Chapter F3

109. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. If a sample contains an isotope with a half-life of 10,000 years, how old would the sample be if 1/8 of the original isotope remained in the sample? F 20,000 years G 30,000 years H 40,000 years I 50,000 years Standardized Test Preparation Chapter F3

110. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. If a sample contains an isotope with a half-life of 5,000 years, how old would the sample be if 1/4 of the original isotope remained in the sample? A 10,000 years B 20,000 years C 30,000 years D 40,000 years Standardized Test Preparation Chapter F3

111. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. If a sample contains an isotope with a half-life of 5,000 years, how old would the sample be if 1/4 of the original isotope remained in the sample? A 10,000 years B 20,000 years C 30,000 years D 40,000 years Standardized Test Preparation Chapter F3

112. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 4. If Earth history spans 4.6 billion years and the Phanerozoic eon was 543 million years, what percentage of Earth history does the Phanerozoic eon represent? F about 6% G about 12% H about 18% I about 24% Standardized Test Preparation Chapter F3

113. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 4. If Earth history spans 4.6 billion years and the Phanerozoic eon was 543 million years, what percentage of Earth history does the Phanerozoic eon represent? F about 6% G about 12% H about 18% I about 24% Standardized Test Preparation Chapter F3

114. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 5. Humans live in the Holocene epoch. If the Holocene epoch has lasted approximately 10,000 years, what percentage of the Quaternary period, which began 1.8 million years ago, is represented by the Holocene? A about 0.0055% B about 0.055% C about 0.55% D about 5.5% Standardized Test Preparation Chapter F3

115. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 5. Humans live in the Holocene epoch. If the Holocene epoch has lasted approximately 10,000 years, what percentage of the Quaternary period, which began 1.8 million years ago, is represented by the Holocene? A about 0.0055% B about 0.055% C about 0.55% D about 5.5% Standardized Test Preparation Chapter F3

116. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Relative Dating: Which Came First? Chapter F3

117. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Relative Dating: Which Came First? Chapter F3

118. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Relative Dating: Which Came First? Chapter F3

119. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Relative Dating: Which Came First? Chapter F3

120. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Relative Dating: Which Came First? Chapter F3

121. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Absolute Dating: A Measure of Time Chapter F3

122. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Absolute Dating: A Measure of Time Chapter F3

123. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Standardized Test Preparation Chapter F3