UNIT 5: GEOLOGIC HISTORY. AT THE END OF THIS UNIT YOU WILL BE ABLE TO Calculate the absolute age of...
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Transcript of UNIT 5: GEOLOGIC HISTORY. AT THE END OF THIS UNIT YOU WILL BE ABLE TO Calculate the absolute age of...
UNIT 5: GEOLOGIC HISTORY
AT THE END OF THIS UNIT YOU WILL BE ABLE TO
Calculate the absolute age of a substance based on its decay rate
Correlate rock layers Create a sequence of events for an
outcrop Obtain information from the
geologic timeline
LABORATORY ACTIVITIES FOR THIS UNIT:
Matching Rock Layers Radioactive Decay Geologic History Timeline Sequence of events
PLEASE ADD THESE TO YOUR TABLE OF CONTENTS IN YOUR NOTEBOOKUnit 5 Geologic History59-61 Geologic history vocabulary62 Ages: absolute and relative63 Radioactive decay: absolute age64 Radioactive isotopes65 Matching/ correlation of rocks66 Order of events
NOW TURN TO PAGE 59 AND NUMBER UP TO PAGE 66
On page 59 at the top please write: Unit 5: geologic history vocabulary
You will be writing out 19 vocabulary words, you may not need up all 3 pages, but I gave you extra room in case you did.
VOCABULARY Absolute age- the actual age, in years of
an event Relative age- the age of a rock or event in
relationship to the age of another rock or event, a comparison
Half life- time required for half of a substance that is unstable to become stable
VOCABULARY
Radioactive dating- the use of a radioactive isotope to calculate the absolute age
Radioactive decay- a breakdown of an unstable atom to a stable atom
Carbon 14 dating- dates organic remains only
VOCABULARY
Uniformitarianism- the present is the key to the past, what happens now happened then
Superposition- youngest layer is on the top oldest is on the bottom
Original horizontality- rock layers form as horizontal layers
VOCABULARY Unconformity- erosional surface, some
layer has been removed, creates a gap in the timeline
Inclusion- older rock within a younger rock
Extrusion- a mass of igneous rock on the surface, exposed to weathering and erosion, contact metamorphism with the layer below only
VOCABULARY Intrusion- a mass of igneous rock
formed between layers, contact metamorphism with layers above and below
Contact metamorphism- heat from an igneous rock that changes the rocks around it
Index fossil- used to match layers, must be easy to identify, lived a short time and covered a wide area
VOCABULARY Isotope- a variety of an element
with a different atomic mass, unstable, likes to break down
Correlation- matching Cross cutting relationship- anything
that cuts through is younger Key bed- rock layer that is used to
identify an event or geologic age
EARTH SCIENCE PICTURE OF THE DAY
http://epod.usra.edu/
I. AGES
A. Absolute ages: Gives you exact numbers 1. example: your age, the year a car was produced(made)
On page 62 of your notebook
I. AGES
B. Relative age: Comparison of one to another
1. no numbers2. approximate ages
a. I am older than my brothers
b. Names of geologic time
On page 62 of your notebook
II. DETERMINING THE AGES (ABSOLUTE AGE)
A. Radioactive decay or half life1. Amount of time it takes half the sample to decay or break down into a stable isotope.
a. paper folding activity
On page 63 of your notebook
II. DETERMINING THE AGES (ABSOLUTE AGE)
B. Radioactive isotopes 1. Carbon -14, organic
materials only (living)a. Examples: cotton, teeth,
bones, trees, bugs, etc…b. Half life: 5.7 x 103 years
On page 64 of your notebook
LAB: RADIOACTIVE MATERIAL?
Everyone needs to wash their hands with soap and water before
we start the lab.
GEOLOGIC MAP OF NYS
Ages Rock names Rock types
young
old
III. MATCHING/CORRELATING LAYERS
A. Key beds: covers everything, marks a time when something BIG happened, it is a time marker.1. Dinosaur extinction: Meteorite impact debris and dust
On page 65 of your notebook
III. MATCHING/CORRELATING LAYERS
B. Other ways to match layers 1. Fossils, animal remains 2. unconformities: erosional surfaces
3. rock and mineral types
On page 65 of your notebook
Where is the unconformity?
Where is the unconformity?
IV. ORDER OF EVENTS
A. Principles that we use1. no process has changed
since the earth formed is called Uniformitarianism
2. Sediment layers are always deposited flat,
Original Horizontality
On page 66 of your notebook
Original Horizontality
See the flat layers?
IV. ORDER OF EVENTS
A. Principles that we use 1. Oldest layers are on the bottom, the youngest are on the top, Superposition
On page 66 of your notebook
What layer is the oldest?
What layer is the youngest?
What came first, the Brunswick sandstone or the Palisades sill?
IV. ORDER OF EVENTS
A. Principles that we use 2.Since the layers are deposited flat
when the layers do not match, something must have happened after they were deposited,
Cross Cutting Relationship a. Faults, Folds, Intrusions,
Extrusions, etc….
On page 66 of your notebook
The horizontal layers had to be deposited first
This was intruded through the layers that were there first.
This is called INTRUSION
See how the layers are
folded over each other
This is extreme
folding that is found often in
mountain areas
More folded layers
The sandstone
layers match and the fault
cuts through them so the layers had to be there
first
As the pressure on the layers increases the folds can only handle so much stress and they break creating a fault.
Look for the faults first!
Match the layers across the faults.
This is an “A”nticline or fold in the rocks