Science Chapter Review Book: Inside Earth Chapter: 5 - Rocks Teacher: Mr. Carl

Objective At the end of this lesson, you will be able to: Explain how rocks and fossils are used to understand the age and geological history of the Earth.

Chapter Terminology: Fossils Relative Age Radioactive Dating Geologic Time Scale Mass Extinction EXIT

Fossils Definition: The preserved remains or traces of living things.

Fossils Explanation: For a fossil to form, the remains or traces of an organism must be protected from decay. Then one of several processes may cause a fossil to form. Fossils found in rock include petrified fossils, molds and casts, carbon films, and trace fossils. Other fossils form when the remains of organisms are preserved in substances such as tar, amber, or ice.

Fossils Example: How are Fossils Made? (click on video to start – it may take a few moments to start)

Quiz Time! Question: What is a fossil? A: Old bones dug up from the Earth B: Sediment that hardens into rock from years of pressure and heat being applied C: The preserved remains or traces of living things. D: Any dead animal or plant is a fossil

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Relative Age Definition: The relative age of a rock is its age compared to the ages of other rocks.

Relative Age Explanation: When you look at a rock containing a fossil, your first questions may be, “How old is it?” You have probably used the idea of relative age when comparing your age with someone else’s age. For example, if you say that you are older than your brother but younger than your sister, you are describing your relative age.

Relative Age Click on this video explaining relative age…

Quiz Time! Question: What is Relative Age? A: Relative age is its age compared to the ages of other rocks. B: The age of my relatives C: Relative age is the number of years since the rock formed. D: In horizontal sedimentary rock layers, the oldest layer is at the bottom and each higher layer is younger than the layers below it.

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Radioactive Dating Definition: measurement of the amount of radioactive material (usually carbon 14) that an object contains; can be used to estimate the age of the object

Radioactive Dating Explanation: Geologists use radioactive dating to determine the absolute ages of rocks. In radioactive dating, scientists first determine the amount of a radioactive element in a rock. Then they compare that amount with the amount of the stable element into which the radioactive element decays.

Radioactive Dating Click on the video on Radioactive Dating…

Quiz Time! Question: What is Radioactive Dating? A: The process of elements breaking down, or decaying by releasing particles and energy B: The rate of decay of each radioactive element C: The process used to achieve a relative date of a rock. D: Scientists first determine the amount of a radioactive element in a rock, then they compare that amount with the amount of the stable element into which the radioactive element decays.

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Geologic Time Scale Definition: A record of the geologic events and life forms in Earth’s history

Geologic Time Scale Explanation: Scientists first developed the geologic time scale by studying rock layers and index fossils worldwide. With this information, scientists placed Earth’s rocks in order by relative age. Later, radioactive dating helped determine the absolute age of the divisions on the geologic time scale. As geologists studied the fossil record, they found major changes in the life forms at different times. They used these changes to mark where one unit of geologic time ends and the next begins. Therefore the divisions of the geologic time scale depend on events in the history of life on Earth.

Geologic Time Scales Click on video to explain Geologic Time Scales

Quiz Time! Question: What is a Geologic Time Scale? A: It consists of only three Eras: Mesozoic, Paleozoic and Precambrian. B: The record of the life forms and geologic events in Earth’s history. C: The time frame of the past 544 million years D: The time frame when life existed on Earth

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Mass Extinction Definition: When many types of living things become extinct at the same time.

Mass Extinction Explanation: The mass extinction at the end of the Paleozoic affected both plants and animals, on land and in the seas. Scientists do not know what caused the mass extinction, but as much as 95 percent of the life in the oceans disappeared.

Mass Extinction Example: Dinosaurs are an example of a mass extinction (click on video to start).

Quiz Time! Question: What is Mass Extinction? A: A time when all of one type of living thing becomes extinct at the same time. B: When all land animals die at the same time. C: A time when many types of living things become extinct at the same time. D: Any time a species dies off and becomes extinct.

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Credits Absolute VS Relative Ages 2011. TaterChron1. Web. 27 Feb. 2012. <http://www.youtube.com/watch?v=JNOmpXo2xlU>. Carl, Carrie. Voice Narration. Web. 27 Feb. 2012. Dinosaur Extinction. 2009. Sheppard Software Com. Web. 27 Feb. 2012. <http://www.youtube.com/watch?v=YQoYF9iRmEs>. Geologic “Eras”, Animated 2009. Pellosborn. Web. 27 Feb. 2012. <http://www.youtube.com/watch?v=SY3MZ_wNFW8&feature=related>. How Fossils Are Formed 2009. Sheppard Software Com. Web. 27 Feb. 2012. <http://www.youtube.com/watch?NR=1&feature=endscreen&v=TVwPLWOo9TE>. Microsoft Office 2007 clipart, movie and sounds Radiometric Dating Age of Earth 2007. Acorvettes. Web. 27 Feb. 2012. <http://www.youtube.com/watch?v=6SxzfZ8bRO4>. EXIT