Transcript 3 Absolute Dating And Early Earth

Topic: Absolute Dating
Absolute Dating is the real, true
age of the rock
Examples - Tree Rings
Varves
•Layers of
sedimentary rock
that were formed in
a lake from season to
season
Radioactive Dating – -
Absolute Dating
Radioactive elements decay steadily.
1. 2. 3. 4. 5. -
Examples Front of ESRT
Daughter Isotope
Parent Isotope
# of Half-Lives
0
1
2
3
4
5
6
Half-Life of
Carbon-14
Age of Rock
(years old)
% of Carbon
Remaining
% of Nitrogen
Example of Half Life
• Your rock contains 3
grams of C14 and 9
grams of N14. How old
is your rock?
• -
Example of Half Life
• A sample of wood that originally contained
100 grams of carbon 14 now only contains
25 grams of carbon 14. Approximately
how many years ago was this sample part
of a living tree?
• -
Example of Half Life
• A rock contains 5 grams of Uranium 238
and 35 grams of Lead 206. How old is the
rock?
• -
Example of Half Life
• A fossil contains 5 grams of carbon 14 and
75 grams of Nitrogen 14. How old is the
fossil?
• -
Final Question:
• A rock containing Potassium 40
undergoes 3 half lives, what is the age
of the rock?
-
Topic: The Earlier Earth
Law of Uniformitarianism
“The present is the key to the past.”
-
Earth is a Dynamic and Evolving Planet
• Changes in its surface
• Changes in life
Origin of Our Solar System
Solar nebula theory
The Planets
Sun and Rotating Cloud
• Planetesimals have
formed in the inner solar
system, and large eddies
of gas and dust remain far
from the protosun.
• -
How old is the Earth?
• 4,600,000,000 = -
An Early Earth
• • Heat sources:
• • • • -
Earth’s Differentiation
• Early Earth – • -
• Lighter silicates
flowed up to
form mantle and
crust.
Why?
The Moon
• -
Earlier Earth Atmosphere
• -
Ocean Formation
• -
Exploring Geologic Time
What has been around for a long time to help geologist
study the Earth?
Final Question:
• The geologic history of an area can best
be inferred by studying
A) erosional processes affecting the area
B) plants and animals now living in the area
C) present climatic conditions of the area
D) bedrock compositions and rock structures
in the area