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Fossils and Geologic Dating - Regular Components → 8.7.1 and 8.7.2

Agenda □ Fossil Notes- Pages 2 Watch the video and take notes. □ Do all organisms create fossils?- Pages 3-5

Obtain supplies from your teacher and find a partner. Follow the directions and answer the questions.

□ Watch Fossil Video Watch the video on my website and give a one sentence summary on the back of this packet.

□ Landfill Tech Archeological Dig – Pages 6-8 Use the pictures to help answer the questions about the archeological dig. CHECK IN WITH TEACHER.

□ Sedimentary Rock Worksheet – Page 9 Complete the worksheet.

□ Relative vs Absolute Time- Pages 10-11 Complete the worksheet. □ Radioactive Half-life Activity- Pages12-13

Complete the radioactive half-life activity with a partner. Give your data to your teacher.

□ Fossil Station Activity- Pages 14-16 Walk around the room and answer the questions associated with each station.

□ Fossil and Relative and Absolute Dating Quiz → 10 Minutes

o Ask any questions you might have and study your notes page

o Take the quiz TOMORROW

You cannot take the quiz the same day you finish the activity. STUDY!!!

o Give your Science teacher your score and percent

70% or Above

(Pick one of the following) 69% or Under

Continue working on the packet STUDY!!! Retake the quiz TOMORROW

NAME:_________________________________________

PERIOD: ____________

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Fossil Notes

What is a fossil? Remains of once living animals or plant that represents ancestors of organisms living today

Does every organism turn into a fossil?

No - Normally they rot or get eaten

They need perfect conditions → Buried quickly / undisturbed

How are fossils formed?

1. Animal dies and is buried by sediment 2. Extreme pressure turns sediment into sedimentary rock 3. Skeleton dissolves and leaves a hole/mold

Dissolved by ground water 4. Minerals crystallize in hole and a cast is formed

Mineral rich water enters mold and leaves minerals 5. Millions of years later, the fossil is exposed on the Earths surface

Earthquakes, building, construction, digging / drilling

What do fossils tell us?

Which organisms were alive in the past The diversity of the types of organisms that were present at any given time. Which organisms became extinct when (and why), How organisms have evolved over time. To see how organisms are related To see how (individual vs group) and where organisms used to live. To have a better understanding of the world around us

How do we get information about fossils?

Type of Fossil Body fossils → Tell us what the animal / plant looks like

Ex: Petrified wood, frozen mammoths, amber Trace fossils → Tell us what the animal did

Ex. Footprints, trackways, Coprolites (poo) Age of Fossil

RELATIVE DATING Approximate time scale Uses rock layers Used when fossils / rock layers in layers

too old for absolute dating Information provided

o Approximately when animals lived o Which animals lived in the same

time periods o What natural disasters happened

(earthquakes, volcanoes, droughts) and when they occurred

o Think: Grand Canyon!

ABSOLUTE DATING Specific time scale Uses radioactive half-life More accurate Information Provided

o Specific age of the fossil o Can only be used up to 70,000 years (depending on the element used)

How it Works: o Certain naturally occurring elements are radioactive and they break

down at predictable rates o Scientists use these rates to measure the half-life of elements

Half life = Time it takes for half the radioactive element to break down

o Scientists compare the amount of an element to the initial amount and the half-life to determine age

If each half-life is 5,730 years old and the sample is 2 half lives then it is 11,460 years old (2 X 5,730 = 11,460)

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Do All Organisms Become Fossils?

Background:

Fossils are made when a living thing dies and is buried by mud, silt, volcanic ash, or sand. Fossils could also be frozen in ice, mummified in hot or cold deserts, or preserved in tar. Usually, all of a living thing's soft parts decay, leaving only the hard parts to be buried, except when a living thing is frozen or mummified. The mud, silt, and sand are called sediments. The sediments have water with minerals in it. The minerals in the water soak into the hard parts, changing them into a rock like material and preserving the hard parts as fossils. Living things which die in or near oceans, lakes, or rivers have a better chance of fossilization than those which die on dry land, because they will be quickly buried. Over thousands and millions of years the sediments form heavy layers which slowly turn into sedimentary rock. Materials:

- 3 Sugar cubes - 2 pieces of clay - 1 beaker - Spoon

Procedure:

1. Make sure you have each of the materials listed above. 2. Sugar Cube 1

o Take the larger piece of clay and wrap it tightly around the sugar cube so the entire cube is covered

3. Sugar Cube 2 o Take the smaller piece of clay and wrap it around the sugar cube so only HALF

the sugar cube is covered 4. Sugar Cube 3

o Leave the third sugar cube alone. 5. Fill the beaker ¾ full of water 6. Place all 3 sugar cubes into the beaker of water 7. Stir the cubes in water until the uncovered sugar cube (#3) is dissolved. 8. Remove the other cubes from the water and examine the remains. 9. Observe what happens and answer the questions below.

Analysis Questions: PLEASE WRITE IN COMPLETE SENTENCES WITH NO ABBREVIATIONS (ex:

b/c)

1. What happened with sugar cube 1? (What are your observations of both the cube and

the clay?)

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

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2. What happened with sugar cube 2? (What are your observations of both the cube and

the clay?)

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

3. What happened with sugar cube 3?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

4. When did the clay help to preserve the sugar cube?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

5. Why did this happen?

________________________________________________________________________

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6. When did the clay not work to preserve the sugar cube?

________________________________________________________________________

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7. Why did this happen?

________________________________________________________________________

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8. Explain how this activity is similar to the way fossils are formed.

________________________________________________________________________

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9. What needs to occur to an organism in order for it to have a chance to become a

fossil?

________________________________________________________________________

________________________________________________________________________

________________________________________________________________________

10. In nature, what could replace the clay to surround the living organism?

________________________________________________________________________

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11. What do you think the stirring could have represented? (hint: it is something we

already studied)

________________________________________________________________________

________________________________________________________________________

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12. In addition to what you answered for #11, what could happen to prevent an organism

from becoming a fossil?

________________________________________________________________________

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Landfill Tech Excavation

It is the year 2216. An archeological group has come across a unknown landfill in the state of

Illinois that has been untouched since the year 2016. The group finds a location and starts a dig

site. As they go through the layers of garbage, they are focusing on finding out more about the

technology that was available over the past 200 years. They create a table showing what was

found at each depth. Below is their data collection from the site.

Layer

7

Layer

6

Layer

5

Layer

4

Layer

3

Layer 2

Layer 1

TOP LAYER

BOTTOM

LAYER

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1. Which item is the oldest?

2. Why were CDs not in layer 2?

3. Why are records not in layer 2?

4. In layer 2, glass bottles were found but no aluminum cans. What does that tell you

about aluminum cans?

5. If the archeologists start digging at another spot, what can they find in a layer with the 8

track tapes?

6. If they dig at another spot and in the top layer they find only cassettes what could have

happened in that area?

The same archeologists find a similar landfill in California. The area has had an earthquake due

to a simple fault. This caused the layers of rock to slip and separate. Look at the table below

and answer the following questions.

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7. What item or items would you find in layer A?

8. Which layer occurred in the 1970s?

9. What item or items could be found in layer C?

10. How could you determine the approximate time of the Earthquake?

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Sedimentary Rock Worksheet Sedimentary rocks are particularly important in the understanding of the Earth’s history. These rocks are formed at the Earth’s surface as layers of sediment (small particles broken down from other rocks) build up, and pressure compresses them into rock. Each layer of rock records the nature of the environment at the time that it was laid down. The layers are the characteristic feature of sedimentary rocks, the oldest ones being located at the bottom of the sequence as they were deposited first. Fossils are probably the most important inclusions found in sedimentary rocks. Knowing something about these prehistoric life-forms and the rock they are found in can help us to recreate environments and ecosystems from the past.

Use the pictures on the right to answer the following questions.

1. Which shell is the oldest?

2. There are no shells in Layer 3, why might this be?

3. No dinosaur bone is found below Layer 2, this might mean:

4. If you also found a softdrink can in Layer 3, what could you say about Layers 3, 4, & 5?

5. Are there likely to be dinosaur bones in any of these layers? Explain.

Sometimes rocks are reshaped as a result of movement. This can be seen when rock layers are not simple straight layers or no longer match up. Faulting occurs when the rock layers move along a weak point or fault line. Fossils are sometimes used to match layers that are no longer contiguous. Some folded or faulted formations may then be eroded to a flat surface before more layers of sediment are deposited on the surface. This is called an unconformity

6. In diagram I, which layer is the same as Layer A?

7. In diagram II, which layers do you think were laid down in the

Ocean?________________________ 8. Which were deposited on or near land? ________________________ 9. What can you say about the top layer in diagram I?

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Relative vs. Absolute Time

Background:

By knowing the age of the rock that a fossil is found in, geologists can usually tell the age of the fossil. Sometimes they cannot give it an exact date, but they know that it is older or younger than another fossil. Dating a fossil by saying it is older or younger than another fossil is called relative dating. If the geologists know the exact age of a fossil, they usually express its age in millions of years ago (mya) that it was formed. Scientists use radioactive half-life data to determine a fossils age. Dating a fossil by assigning it a specific age is called absolute dating. Procedure:

1. Make a relative time scale out of 7-8 events that have occurred in your life.

a. Ex. Include important events such as your birth, something you did today,

starting kindergarten, and losing your first tooth.

b. REMEMBER: These events only show chronological order, NOT exact dates

2. Using your relative scale, make an absolute time scale by adding dates

3. Answer the analysis questions below

Example:

Example Time Scale

Relative Time Scale Absolute Time Scale

I was born. I was born. August 21, 1985

I took my first steps. I took my first steps July 15, 1986

My little sister was born My little sister was born May 30, 1988

First high school RBI First high school RBI March 21, 2001

Graduated high school Graduated high school May 28, 2004

Graduated college Graduated college May 31, 2008

Got my first job Got my first job August 26, 2009

Today Today November 30, 2013

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My Time Scale:

Relative Time Scale Absolute Time Scale

I was born. I was born.

Today Today

Analysis Questions:

1. Describe how we determine relative time.

2. Describe how we determine absolute time.

3. Why are both relative time and absolute time to reconstruct past timescales?

See your teacher to see a geologic timeline.

4. According to geologic time what is the percentage of time humans have lived on the Earth?

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Radioactive Half-Life

Background: One characteristic of radioactive material is that radioactive isotopes spontaneously give off particles. This process, called radioactive decay, changes the nucleus of the material. The length of time it takes for half of a sample of radioactive material to decay is called the half-life. Each radioactive isotope has a characteristic half-life, ranging from less than a second to millions of years. Carbon-14 is a special unstable element used in the absolute dating of material that was once alive, such as fossil bones. Every 5,730 years, half of the carbon-14 in a fossil specimen decays or breaks down into a more stable element. In this activity, you will use pennies that can land “heads up” (nuclei that have undergone radioactive decay) or “tails up” (nuclei that haven’t yet decayed) as a simplified model of half-life.

Procedure: 1. Trial 1

a. Count to make sure you have 100 pennies b. Shake the pennies up in the cup and roll them into the box lid c. Count how many pennies are heads up and record the data below d. Remove all of the pennies that are heads up. e. Repeat steps 2-4 five more times

i. Make sure you are recording your data below 2. Trial 2 and 3

. Repeat each of the steps above 3. Average your data from the three trials

. Add all three numbers together for each round and divide it by 3 4. Type your averages in the class excel document 5. Graph the CLASS DATA below 6. Answer the analysis questions

Data:

INDIVIUDAL DATA

CLASS DATA

Round Trail 1 Trail 2 Trial 3 Average

Round Class Average

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0

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Analysis Questions: USE COMPLETE SENTENCES.

1. What did the pennies represent?

2. What did each trial represent?

3. What pattern do you notice?

4. How does your data compare to the class data?

5. Compare your graph with the “Half-life of Carbon-14” graph on the right. What similarities do you see?

6. Why is radioactive decay helpful for determining the age of fossils?

7. If a “sample” of pennies contained 75 heads and 25 tails, how many half-lives would have passed since the “sample” formed. Explain your answer.

8. If each half-life was 2000, years how many years old would the above sample be?

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Fossil Station Activity

Station 1 1. Why do you think we cannot actually replicate this procedure in real life?

Station 2 http://www.ucmp.berkeley.edu/education/explorations/tours/fossil/index.html

2. What are 2 things fossils tell us?

3. Which is better for creating a fossil: remains that are buried quickly or slowly?

4. Why?

5. How do decomposers stop a fossil from being created?

6. Do organisms have to be buried to become a fossil? Explain.

7. Why do you think we do not find fossils for things like worms?

8. How do fossils get destroyed?

Station 3

9. Compare and contrast fossil A and B (use appearance and fossil type)

10. Identify each fossil type at your station

Fossil A: __________________________

Fossil B: __________________________

Fossil C: __________________________

Station 5 11. Compare and contrast fossil A and B (use appearance and fossil type)

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12. Identify each fossil type at your station

Fossil A: __________________________

Fossil B: __________________________

Station 6

13. Do you think it is beneficial for scientists to continue their research on the fossil record?

14. Why?

Station 7 15. Diagram 1: Identify the layers from OLDEST to YOUNGEST

16. Diagram 2: Identify the layers from OLDEST to YOUNGEST Station 8

17. Complete the following chart

Grams of C-14 Amount of time that has

passed (years) Number of half lives

Station 9

18. How might studying fossils help us in uncovering changes that have occurred in the world around us and to particular animals?

(TURN OVER FOR ANOTHER STATION)

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Station 10

19. The following fossil was located 200 miles above sea level on a mountain. Compare its original environment to its current one and explain how it got here.

a. Original environment:

b. Current environment:

c. How did it get here?