Earth History
Competency
Student can analyze evidence from the fossil record and landforms in order to draw conclusions regarding the history of earth.
Student can analyze evidence from the fossil record and landforms in order to draw conclusions regarding the history of earth.
Learning Targets
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Fossil Project
Students will work in groups to uncover the mysteries about a new fossil discovery that they have come across. They will learn how the fossil formed, discover the fossil's age, both relative and absolute, based on the rocks and layers around it and will uncover how the fossil came to be at its final resting place. The Project Page, with the rubric and details can be found HERE. |
Earth History Timeline
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ChronoZoom
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Fossils
How did fossils form?
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Relative Dating
The Law of Superposition
One of the ways that scientists can determine dates of rocks and fossils is through the relative dating method. In this method we can decipher which rocks or fossils came first and which are younger based on the position of these objects. Relative dating does not tell us how old something is. It just tells us if it is younger or older relative to something nearby. For example, if two people, say John and Sally, are standing next to each other I can tell that John is taller. He is taller relative to her. I cannot, however, know exactly how tall John is just by looking at him.
Click on the link below to read more about relative dating and trying your hand at the practice. Relative Dating Notes and Practice |
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Index Fossils
Just like the index in a book tells you what page you can find something on, an index fossil tells you when in history you can find things. An index fossil is a fossil of an organism that was widespread (lived in a lot of places) for a short period of time. They are useful because they can tell us
Index Fossils Notes and Practice |
Absolute Dating
When you look at a football player standing next to an olympic gymnast it is easy to tell that the football player is heavier than the gymnast or that the gymnast is shorter than the football player. But, just by looking, we cannot tell exactly how heavy the football player is or how tall the gymnast is! So, although we know their height and weights relative to one another, we do not know these absolute values.
We've just learned how to use the law of superposition and index fossils to determine the relative age of rocks and fossils but how do we know their absolute age? Scientists have come up with a brilliant way to estimate the absolute age of rocks and fossils using radiometric dating. In short, radiometric dating is when scientists measure how much of a certain kind of atom has changed into another kind of atom due to its radioactivity. And because we know the rate at which these atoms change we can calculate their age based on how much is left over. Take a look at the notes and video for more information! |
Watch the video above and complete the practice using the link below.
"Radiometric and Absolute Dating" Notes and Practice on Canvas
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Vocabulary