Transcript The Rock Record Chapter 8 section 1 5/13/14

May 13, 2014
Open up your ISN. Call the next
available left side page #84.
Title the page “Vocabulary”.
Call the following page #85.
Title the page “The Rock/Fossil Record
Goals”
Today’s goal:
Explain how scientists determine the relative age
of rock layers.
The Rock Record
Chapter 8 section 1
5/13/14
ISN 86 – “DIAGRAMS”
ISN 87 – “NOTES”
And no…..we are not talking
about this rock 
These are the types of rocks I am referring to…
State the principles of
uniformitarianism…. What does this
principle tell us?
• Current geologic processes, like erosion,
shaping the Earth now, shaped the Earth in
the past.
Basically…. The past is the key to the present!
Explain how the law of superposition
can be used to determine the relative
age of rocks…
• Relative age of rocks: Indicates that one layer is
older or younger than another layer but does not
indicate the rock’s age in years.
• Law of superposition: States that an undeformed
sedimentary rock layer is older than the layers above
it and younger than the layers below it.
Law of superposition
-Top layers are youngest
-bottom layers are the oldest
Unconformities: An interruption in the geologic record
There are 3 types of unconformities
1. Nonconformity: When a stratified rock rests upon
unstratified rock.
2. Angular unconformity: The boundary between a set
of tilted layers and a set of horizontal layers.
3. Disconformity: The boundary between horizontal
layers of old sedimentary rock and younger, overlying
layers that are deposited on an eroded surface.
Applying the law of crosscutting relationships to
determine the relative age of rocks…
• Law of crosscutting relationships: States that
a fault or igneous intrusion is always younger
than the rock layers it cuts through. The law of
crosscutting relationships can be used to
determine the relative ages of rock layers and
the faults an intrusions within them.
Assignment
• On page 206 in your handy dandy textbook answer
questions 1-6. Please, I am begging you… PLEASE
PLEASE PLEASE use complete sentences when
writing your answers. College is just around the
corner and all of this one or two word answers are
going to earn you a BIG FAT incomplete…. Just sayin’
Thanks  Ms. Flanagan