Fossil TTK 1 Relative dating Superposition Unconformity Absolute

Fossil TTK #1 Relative dating Superposition Unconformity Absolute dating Intrusion Disturbance pg 158 (disturbs rock layers) Fossil Index fossil

Science Do Now: 9 - 22 EQ: Which came first? LG: Understand how relative dating and the law of superposition determine the age of rock layers and fossils. HW: Directed Reading 6 -2 Due Wednesday Today ~ Relative Dating ppt w/ notes HAPPY BIRTHDAY MS MILLER!!!!

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.

Here is the correct order: • • I was hungry. I went to the store. I selected two apples. I stood in the checkout line. I gave the cashier money. The cashier gave me change. I walked home from the store. Paleontologists have to put layers of rock in order to figure out how old things are!

Relative Dating Which Came First? ? Chapter 6, Section 2 HOW CAN WE USE THIS IDEA IN THE REAL WORD!!

Absolute Age/Dating How old an object or event actually is Described in numbers Ex. The Trilobite fossil is 450, 000 years old Your actual age is _____years and ____ months

Relative Age/Dating Figure out whether an object or event is older or younger than other objects or events. • How it is done – compare the age of a rock to the rocks around , above or below • Use words like: older, younger, first, second, third Ex: If you are a middle child… you are younger than your sister. BUT… You are older than your brother

It is not just that easy…. • Not all rock sequences are arranged with the oldest layers on the bottom and the youngest layers on the top… • There are disturbances! “I feel a disturbance in the force” • The forces within Earth can push other rocks into the sequences HOW? ØTilt or fold rock layers! ØBreak sequences into parts that move! ØSome sequences are even upside down!

Disturbances When the original rock layers have been moved from their original placement. There are four different types of disturbance. 1. Faults 2. Intrusions 3. Folding 4. Tilting

Let’s Talk about the Disturbances! Disturbances

Fault A break in the crust where the crust moves

Intrusion Magma squeezes into rock and cools Batholith

Folding Rock layers bend and buckle from Earth’s internal forces

Folding

Tilting Internal forces push rock layers up

Missing Evidence • Missing rock layers or a break in the sequence = unconformities • A break in the geologic record occurs: Ø rock layers are eroded (was there and now it’s not) Ø sediment is not deposited for a long period of time (was never there) EASY… You just look for what is

Let’s date some rock strata • Put the layers in order!

Did you get it correct? • Make sure you correct your paper! By erosion

Try this one!

Did you get it? 12 11 10 9 5 8 4 7 3 2 1 6

WHOA!! What happen here? ?

Science Do Now: 9 - 23 EQ: Which came first? LG: Understand how relative dating and the law of superposition determine the age of rock layers and fossils. HW: Directed Reading 6 -2 Due Wednesday Today ~ Act: Mt. Fossil TODAY: THE FIRST FULL DAY OF FALL? ?

Science Do Now: 9 -24 EQ: Which came first? LG: Understand how relative dating and the law of superposition determine the age of rock layers and fossils. HW: Finish Clues to Rock Layers WS, Study TTK Do Now Q: What is the Principle of Superposition? 1. Take out Relative Dating activity from yesterday 2. Stack Directed Reading or your Agenda Today ~ complete Rock Layer Clues activity

The Principle of Superposition • Younger rocks on top and Older rocks on bottom! C Youngest B A Oldest

Relative Age/Dating Figure out whether an object or event is older or younger than other objects or events. • How it is done – compare the age of a rock to the rocks around , above or below • Use words like: older, younger, first, second, third Ex: If you are a middle child… you are younger than your sister. BUT… You are older than your brother

Finding Clues to Rock Layers Activity!!! You be the detective!

You be the Detective! • Fossil clues give geologists a good idea of what life on earth was like millions or even billions of years ago! • Problem: How can YOU use fossils and geologic features to interpret the relative ages of rock layers?

Remember the Index Fossils • Used to date other fossils and rock layers. • Requirements for an Index Fossils - from TRILOBITE animals that: • • Existed for a short period of time Were abundant, there were many Lived all over the world EX. Trilobite (found in N. Georgia) EUOMPHALUS But wait…. There’s more….

Science EQ: Which layer is older? Do Now: 9 -25 LG: Understand how relative dating , absolute dating and the law of superposition determine the age of rock layers and fossils. HW: Review sheet - Test Monday Do Now Q: What is an unconformity? 1. Take out Fossil Mt paper from yesterday - stack Today ~ Dating Practice ~ Review Sheet

Site 1 1. What “fossil clues” in layers A and B indicate the kind of environment that existed when these rock layers were formed? How did the environment change in layer D? • Fossils of marine animals in A and B = ocean • In layer D – Dinosaur tracks and a leaf = land

2. Which layer is the oldest? How do you know? • A is the oldest because the Principle of Superposition states that the lowest layer is the oldest.

3. Which of the layers formed most recently? How do you know? • Layer G formed most recently because the Principle of Superposition states that the top layer is the youngest.

4. Why are there no fossils in layers C and E? • Layers C and E are extrusions of igneous rock (igneous rocks do not contain fossils)

5. What kind of fossils occurred in layer F? • Dinosaur, Plant and bird fossils trace and carbonaceous film

Site 2 6. Which layer at Site 1 might have formed at the same time as layer W at Site 2? And why? ? • Layer B – same fossils

7. What clues show an unconformity or gap in the horizontal rock layers? What might have happened to these rock layers? • Layers E and D are missing between layers X and Y eroded away • Below layer W layer A is missing never formed

8. Which is older, intrusion V or layer Y? How do you know? Remember: an intrusion forms when magma squeezes into existing rock and solidifies to become an igneous rock • Layer Y is older • An intrusion is always younger than the layers it forms in

9. Working as a geologist, you find a rock containing fossils. What information would you need in order to determine the rock’s age relative to one of the rock layers at Site 1? • You would need to know if any layers at Site 1 contained the same index fossils.

#1 4 3 5 2 1

#2 4 5 3 1 2

#3 1 3 2

#4 – careful with this one! Some layers will be labeled with the same number 9 7 7 3 6 5 8 4 2 1 3 2

#5 9 2 1 4 3 7 6 5 8