Transcript relative age - sarabrennan

Friday, September 23, 2011
Monday, September 26, 2011
Complete Determining Which is Older Worksheet
Warm Up: Copy and Match definition with term
. Name the three types of rocks AND describe how
each is formed
a. ___________ - ______________________
b. ___________ - _______________________
c. ____________ - _____________________
In which layer would you expect to find the most
fossils? Why?
Homework: 1. Color each rock layer and Complete
Friday, September 23, 2011
Monday, September 26, 2011
Law of Superposition
Relative Ages of Rocks Activity
Law of Superposition - The law states that strata that
are younger will be deposited on top of strata that are
older, given normal conditions of deposition.
•if undisturbed, oldest on the bottom and
youngest on the top
Strata – horizontal layers of rocks
Unconformity - a buried erosion surface separating two
rock masses or strata of different ages (this is where the
pattern changes)
Intrusions and Extrusions: Make of Igneous Rock and
always younger than the rock layer it cut through
Movement of Tectonic plates can disturb layers
•Can bend layers like a taco
•Molten lava can cut through layers
Determining Which is Older worksheet
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Tuesday, September 27, 2011
Wednesday, September 28, 2011
Tuesday, September 27, 2011
Wednesday, September 28, 2011
Complete Radioactive Dating Activity Graph and Questions
Read Section 2.3 of Unit A in textbook (Answer ?’s 1-3)
Radioactive Dating, Half Life and Absolute Age Notes
“Sweet” Radioactive Simulation
**Please have your Determining Which is Older
worksheet out so I can check it. If you have your
progress report, please put it on the supply box.
Radioactive Decay- When rocks contain unstable
elements that break down releasing particles and
energy
- Radioactive elements only occur in igneous
rocks that are formed by magma.
- As soon as the igneous rock is formed, it
starts to decay and change into another
element.
Half Life – the time it take for half of the
radioactive atoms to decay
- constant for each element
- Carbon’s Half Life = 5,730 years
- used to date living organisms
- Potassium- 40’s Half Life = 1.3 billion yrs
Warm Up:
1.
When studying an undisturbed rock core, how do
you know which is the oldest and youngest rock
layer?
2.
When might the youngest layer in sedimentary
rock not be on the top?
3.
Can you determine the exact age of rock by
studying layer positions?
4.
Use what you have learned last period to write a
definition for relative age.
Homework: 1. Create Graph from Radioactive Activity
2. Answer the questions that go with the
activity from class.
3. Read Section 2.3 of Unit A of textbook
- Answer questions 1-3
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Absolute Age - Geologists use radioactive
dating to calculate the absolute ages of rocks
- Moon rocks = 4.6 billion years old
Absolute Age vs. Relative Age
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Technology Used to Measure
Radioactivity
Geiger Counter
Ionization Chamber
MicroR Meter
Half-Lives
• Almost always need to make a chart to visualize
Original
Rock
1 Half Life
2 Half Lives
3 Half Lives
4 Half Lives
Half Lives
Percentage of
Radioactive
Material in Rock
Number of Half
Lives
100% - 50%
1
50% - 25%
2
25% - 12.5 %
3
12.5% - 6.25%
4
6.25% - 3.126%
5
50%
decayed
50%
Radioactive
One Half Life
Element Brennan is found in an
igneous rock and we are trying
to determine the rocks age.
We know Brennan’s half life is
approximately 3,000 years and
that the rock is currently 50%
25%
6.25%
radioactive.
How old is the rock?
100% Radioactive
Igneous Rock
75% decayed
87.5% decayed
94% decayed
25% r-a
Two Half Lives
Three Half Lives
Four Half Lives
Half-Lives
Last Practice Question:
A rock contains a radioactive element with
a half life of 100 million years. Tests show
that the element in the rock has gone
through three half lives.
How old is the rock?
Japan
Radioactive ways can be harmful to our health
Ticket Out the Door
• Make a Venn Diagram to compare and
contrast absolute and relative age.
– Which does radioactive decay fall under?
– Which does law of superposition fall under?
Thursday, September 29, 2011
Friday, September 30, 2011
Thursday, September 29, 2011
Friday, September 30, 2011
Work on Castle Learning Assignments
Prepare your Notebook for a Upcoming Check!!
Index Fossil Notes
Index Fossil Activity
Warm Up: Put rock layers in order from oldest to
youngest. Explain your reasoning.
2
D
1
Fossil Formation – An organism that was fossilized
in rock must have lived during the same time span
in which the rock formed.
-Scientists have determined when specific
fossilized organisms lived
-Knowing this helps determine rocks age
C
B
E
A
3
H
I
F
G
J
K
L
L
M
M
N
N
O
P
Homework: 1. Work on Castle Learning Assignments
2. Prepare your notebook for a check!
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Index Fossils – Organisms that lived in many areas
during only a specific time span (extinct now)
- Knowing the time span that organism
lived, can help to estimate the rocks age
- Can be used to compare the ages of rock
layers in different parts of the world
Example – Mollusk Inoceramus labiatus is a
sea creature that lived many years ago
- It appeared on Earth 144 million years ago
- It became extinct 65 million years ago
- If we find a rock layer that has this fossil in
it, we know the rock is between the ages of
144 and 65 million years old
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Monday, October 3, 2011
Tuesday, October 4, 2011
Study for Quiz on Determining Rock Age
Monday, October 3, 2011
Tuesday, October 4, 2011
Notebook Check (1-26)
Centers
Warm Up: Get notebook out and ready for notebook
check!
Homework: 1. Study for Quiz!
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