CREATE A TIMELINE LIST 10 TO 15 EVENTS WITH THE OLDEST ON THE BOTTOM AND THE YOUNGEST ON THE TOP EXAMPLE: TODAY MRS. WILLIAMS GOT MARRIED DAY MRS. WILLIAMS WAS BORN

Fossils and The Law of Superposition Liz LaRosa 5 th Grade Science http:// This PPT was created with the information from the FOSREC Activity “Who’s on First?” and “Fossil Inferences” by UEN.FOSRECFossil Inferences

Today: What evidence do we find in rocks to explain the events in Earth’s history? You will describe the age of rocks and fossils in terms of absolute age and relative age. You will correctly sequence and build a rock column using the fossils of organisms found within the layers.

Fossils and Superposition What is a fossil? The trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock What is a superposition? Younger rocks lie above older rocks if the layers have not been disturbed

Relative Dating and Index Fossils What is relative dating? ◦ Any method of determining whether an event or object is older or younger than other events or objects. What is an index fossil? ◦ A fossil that is found in the rock layers of only one geologic age and is used to establish the age of the rock layers. ◦ Is found in rock layers around the world, ex Trilobites

Activity # 1 On your desk, you have 8 large colored index cards with nonsense letters placed on them. Your task is to determine what the correct sequence of the letters are. You have two clues: 1.The card with the letters “C” and “T” is on the bottom, or the oldest layer 2.Look for a card that has either a “T” or “C” written on it for the second layer

C T AGC UA NBU NB ON DXO MD This is one possible way to arrange the cards. Questions: 1.What letter is the oldest? 2.What letter is the youngest? 3.What letter showed up the most? 4.Which letters only showed up once? 5.Which letters could be index fossils? 6.How did you know which was older: “M” or “X”?

Law of Superposition States and explains that in an undisturbed bed, older rock layers are found in deeper layers of Earth and younger rock layers are found in higher layers. Explains that the same is true for fossils found within rock layers. We can use rock layers to describe the relative age of fossils, other rock layers in the column and even use fossils to determine the relative age of other rock layers across the world!

Activity # 2 Flip your eight index cards over Arrange the index cards that represent layers of rock and fossils Clues: 1.The oldest layer has the letter “M” in it 2.Find a rock layer that has at least one of the fossils you found in the oldest rock layer 3.Extinction is forever - once an organism disappears from the sequence it cannot reappear later

Teacher Note: I replaced the letters with nonsense letters b/c spelling the word “organism” was too easy for my 5 th graders

To think about… What problems did you run into when trying to arrange the fossils into the correct sequence? Would this have been more difficult if you did not know which layer was the oldest to start the activity? Which organism is the most complex of all the fossils and why?

Big Picture: Rock Record = allows scientists to determine and describe the relative age of rock layers and fossils. Law of Superposition = helps scientists correctly sequence the order of rock layers and events in Earth’s history. Fossils can be used to determine and describe the relative age of rock layers

Test Your Knowledge: 200 MYA 100 MYA 150 MYA