Science Today:Future Paleontologist Project

Presentations

Today’s We’ll also Hand In:• EH Unit Study Guide• Rock Layer Puzzles Packet (if you still have

this)• “Time Marches On” Reading Guide (6.1)

3/7: Science StarterList the rock layers & events in order from oldest toyoungest.

Important Science Dates:

Mon. 3/7: • Rock layer puzzles packet dueWed. 3/9: • Sign-up Future Paleontologist

PresentationsThurs. 3/10: • EH Unit Test (& study guide due)• Future Paleontologist Application Projects

Due (Presentations will start today) Fri. 3/11: • Future Paleontologist Presentations-cont.

Important Dates: Thurs. 3/10: EH Unit Test •Application Project Presentations•EH Study Guide Due

Fri. 3/11: •Application Project Presentations-cont.

3/9: Science Starter1. How are Relative Dating & Absolute Dating

Similar? How are they different?

Similarities Differences

3/9: Science Starter1. How are Relative Dating & Absolute Dating

Similar? How are they different?

Similarities Differences

• Both try to find out how old an object is

Relative: (a comparison)•Find whether something is older or younger than another object. •Law of Superposition Absolute: •Find the exact age of an object•Radiometric dating

Science Starter 3/8:1. True or False? Most organisms that have lived on

Earth died and decomposed without leaving a fossil.

2. After 1 half life, what are the percentages of unstable atoms and stable atoms in a radioactive element?

• A. 100% unstable atoms, 0% stable atoms• B. 50 % unstable atoms, 50% stable atoms• C. 25% unstable atoms, 75% stable atoms3. Mrs. Keefe’s friend has 2 naughty dogs that she

frequently has to dog-sit (It’s horrible!) . Atza is 4 years old and Coby is 1 year old. Do you know the dogs’ relative or absolute ages?

3/7 Science Starter: 1. What word describes the time it

takes for half of a radioactive sample to decay?

2. Name 2 types of radiometric dating.3. If anyone brings cookies as part of

their application project, what must we not let Blake do?

2/28: Science Starter: Use your book, chapter 6, section 3 to find the answers to the following questions.1. What is absolute dating? 2. What word describes the time it

takes for half of a radioactive sample to decay?

3. Name 2 types of radiometric dating.

Absolute DatingChapter 6, section 3

Cassette Tapes-1970s-90s

iPods-10/23/2001CDs-1980s

Records-early 1900s

8-Tracks-1960s-80s

Absolute Dating: determining the actual age in years of an event or object.

Radioactive Dating of Rocks:

To determine the actual age of a fossil or rock scientists use radioactive dating and element half life to determine the ages of rocks (Absolute Dating)

Isotope: An atom with the same # of protons but with different # of neutrons. • Some isotopes are radioactive

(unstable)

Isotopes-cont.• Unstable Isotopes will change (& try to

become more stable) over time

• An Unstable Isotope (radioactive)works towards stability and changes into another kind of element.

Ex. Potassium-40 decays to argon and calcium.

Radioactive Decay:

• Radioactive decay – The process where radioactive substances (unstable) break down (change) into more stable substances.

• Occurs at a steady (predictable)rate

Radioactive decay (p. 162)

Unstable

Stable

The decay process occurs at a steady, constant rate

Radiometric Dating: (ratio)

Parent materialDaughter material

Radiometric Dating of Rocks:

Radiometric Dating: process of determining the exact age of a sample, based upon the ratio of parent material (old stuff) to daughter material (new stuff) .

Half Life: the length of time it takes for half of the radioactive atoms to change from an unstable form into a stable form (p. 163)• When rock forms = 100% unstable,

0% stable• After 1 half life = 50% unstable 50%

stable• After 2 half lives = 25% unstable 75%

stable

Types of Radiometric Dating

1. Potassium-Argon Method: • Potassium Half-life = 1.3 billion

years2. Uranium-Lead Method:• Uranium Half-life = 4.5 billion years3. Rubidium-Strontium Method:• Rubidium Half-life = 49 billion years4. Carbon-14 Method: • Carbon Half-life = 5,730 years

Johnsonium 1027: half life of 5 yearsSchmelingium 327

100% Keefeium 0 half-life

50% Keefeium50% Meyerium 1 half-life

25% Keefeium75% Meyerium2 half-lives

5 Year

s

5 Year

s

Uranium 235: half-life 700 million yrsLead 207

50% Uranium

235

50% Lead 207

25% Uranium

235

75% Lead 207

700 million years old

1400 million y.o.

100% Uranium

235

0% Lead 207

2 half-lives 1 half-life

0 half-lives

Rock Formation 0 years old

Objectives: (you should be

able to…)•Explain how fossils are used to establish the Earth’s historyDetermine the difference between absolute and relative time

Know the importance of index fossils in geologic time

Understand how half life is used to date rocks

Understand where fossil fuels come from and the difference between renewable and nonrenewable resources

1. True or False? Most organisms that have lived on Earth died and decomposed without leaving a fossil.

2. After 1 half life, what are the percentages of unstable atoms and stable atoms in a radioactive element?

• A. 100% unstable atoms, 0% stable atoms• B. 50 % unstable atoms, 50% stable atoms• C. 25% unstable atoms, 75% stable atoms

3. One example of a nonrenewable resource is ___________.

• A. wind power• B. coal• C. wood

4. Ms. Johnson’s friend has 2 naughty dogs that she frequently has to dog-sit (It’s horrible!) . Atza is 4 years old and Coby is 1 year old. Do you now know the dogs’ relative or absolute ages?