Presentation on theme: "Sept.10, 2011 LEQ 4 Law of Superposition"— Presentation transcript:
1Sept.10, 2011 LEQ 4 Law of Superposition Homework Due tomorrow!Words to know: relative age, absolute age, law of superposition, index fossil, intrusionDo now:Do you have brothers/sisters?If so, how old are they? Are they older or younger than you?If not, how old is your closest friend? Are they older or younger than you?
2LEQ #4: What information do humans get from rock layers, index fossils, and ice cores in order to paint a picture of Earth’s History?By the end of today, SWBAT…Compare and contrast absolute and relative ageUnderstand and apply the law of superposition to diagrams and descriptionsExplain how index fossils are used to date rocks
3Activating Strategy Put the following events in order: Nuclear Bomb dropped on Hiroshima, Japan (1945)George Bush became President (2000)Pluto was no longer considered a plant (2006)The Internet was “invented” (1994)The U.S. launched the first space shuttle (1981)How did you decide to put them in order?
4Look back at your words to know… relative age absolute age What does relative mean? Think about how things relateWhat does absolute mean? Think about mathWhat do you think these words mean when describing age?
5T-Chart Relative Age Absolute Age -Tells age compared to something else-Uses words like “older,” “younger,” and “same age as”-Ex: I am younger than my brother.-Tells the exact age-Uses numbers-Ex: My brother is 16.
6Pair and Write! With your partner: 1.) Tell each other your absolute age2.) Write a sentence about how old YOU are RELATIVE to your partner3.) Discuss What is the difference between absolute and relative age?
7Scientists use rocks to figure out Earth’s History! Ask students which rock layer is older, the one at the bottom (point) or the one at the top (point)? They should say the one at the bottom.We can see 2 BILLION years worth of Earth's geologic history in the Grand Canyon!
8You just figured out the… Law of Superposition!!!
9Law of Superposition The Grand Canyon Define ItIn undisturbed sedimentary rock layers,-Oldest rock layers are at the bottom-Youngest rock layers are at the topDraw itExampleThe Grand CanyonSentenceThe Law of Superposition tells us the relative age of rocks.Law of Superposition
12INTRUSION!!!Magma that pushes through rock layers. Is younger than the layers it cuts across because the layers had to be there before it could cut across them!.Science says… intrusion!Science says is a hand motion game. When science says intrusion, take your hand and push it up into the air like you were magma pushing through rock.
13Hot Question!If you found this fossil in your backyard, what could you infer about how your backyard looked in the past?
14Absolute Dating Techniques Index Fossils: fossils of a species that only existed during a limited timeThe fossil is the same age as the layer of rock it is inIf there is a fossil in a rock layer, and we know what time period the animal lived, we can conclude that the rock was formed during that period.After introducing index fossils, ask students which fossils could be index fossils in this diagram (2, 5, 3). Say, well if we know that fossil 2 is 50 million years old, what do we know about the layer it is in? If we know that fossil 5 is 25 million years old, what do we know about the age of the layer it is in?
15Index fossils help scientists figure out how old rock layers are!
16How to find the absolute age of an index fossil… Radioactive dating… more to come on this, but take a look at this chart…Think.Pair.Share.
17Use the diagrams on your desk Use the diagrams on your desk. With your partner, answer the question on your dry erase board. When I say “3-2-1, Boards Up,” you should hold your board in the air. If your board does not go up immediately, you will be DQ’ed for that question.
18Real Life Practice Look at the cup on Ms. K’s desk What is the oldest rock layer? How do you know?
19Real Life Practice Look at the cup on Ms. K’s desk What is the youngest rock layer? How do you know?
20Real Life Practice Look at the cup on Ms. K’s desk Imagine that there is a layer of magma pushing up through all 4 “rock” layers. What is this called?
21Real Life Practice Look at the cup on Ms. K’s desk List all rock layers in order from oldest to youngest.
22Real Life Practice Look at the cup on Ms. K’s desk What is the name of the law that tells us this is true?
23Hot QuestionThe law of superposition states that in horizontal layers of sedimentary rock, each rock layer is ___________.a. Younger than the layer above it and older than the layer below itb. Neither older nor younger than other layersc. Older than the layer above it and younger than the layer below itd. Always older than any vertical layers