Transcript Chapter 8 Study Notes

Chapter 8 Section 2
Review Page 196
Relative Age Dating
Absolute Age Dating
2. Explain why calculations
of absolute age based on
rates of erosion and
deposition can be inaccurate.
The rate at which sediment is
deposited or eroded away can
vary from year to year due to
many factors.
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3. Describe varves, and
describe how and where they
form.
Varves are layers of sediment
made of one layer of sand covered
by one layer of silt. They are
deposited at the bottom of glacial
lakes and represent one year of
deposition.
Varves
4. Suppose you have a shark’s tooth
that you suspect is about 15,000
years old. Would you use 238U or 14C
to date the tooth? Explain your
answer.
You would use radiocarbon (14C) dating because the
object is organic and because it is too young to be
accurately dated by using 238U.
Radiocarbon Dating: Parent to Daughter
Chapter 8 Study Notes
Section 2: Determining Absolute
Age
1
The ______ age of an object is called
_______ age.


numeric
absolute
2
_______ age is the ______ age of an
object.


Absolute
numeric
3
_______ are banded _____ of sediment
deposited _________ in glacial lakes.



Varves
layers
annually
13
A ______ is most like a tree ____.


varve
ring
14
Radioactive ____ is used to compare the
absolute age of rocks because radioactive
decay happens at a relatively ______ rate.


decay
constant
15
________ dating is determining age
through _________ of isotopes.


Radiometric
comparison
16
In __________ decay, parent isotopes are
compared to __________ isotopes.


radioactive
daughter
17
In ________ dating, scientists compare
the proportion of a radioactive ______
isotope to a stable _________ isotope.



radiometric
parent
daughter
18
A ________ is the time it takes for half of a
sample of radioactive isotope to decay.

half-life
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