Chapter 8 Basics
How old is the Earth?
4.6 billion years old
Which principle says that sedimentary rocks tend to form horizontal layers when left undisturbed?
A. Superposition
B. Crosscutting Relationships
C. Original Horizontality
D. Uniformitarianism
C. Original Horizontality
When discussing isotopes what do we call the isotope that you start with and what do we call the isotope that it decays into?
Parent isotope
Daughter isotope
If you have a fossil that has been through 4 half-lives and each half-life is 20 years, how old is the fossil?
80 years old.
When is your test on Aging (chapter 8)?
Monday, 10/5
What do we call an element that has a different number of neutrons?
A. Neutrino
B. Isotope
C. Gamma Particle
D. Quark
B. Isotope
What law says a fault or body of rock is younger than any other body of rock that it cuts through?
A. Superposition
B. Crosscutting Relationships
C. Original Horizontality
D. Uniformitarianism
B. Crosscutting Relationships
If you have 200g of Nitrogen15, how much of it will you have after 3 half-lives? (Sorry, I couldn't insert a chart!)
25 grams
If you have 40 grams of Carbon13, how many half-lives have to occur for there to be less than 3 grams of it?
4 half-lives
Define fault.
A break in earth's crust that causes rock to move.
How are relative and absolute aging different?
Relative aging tells you how old something is in relation to something else (comparison)
Absolute aging gives you the numerical age of something.
What principle says that geological processes that occur now also occurred in the past?
A. Superposition
B. Crosscutting Relationships
C. Original Horizontality
D. Uniformitarianism
D. Uniformitarianism
See "Radiometric Dating" for 200 first
If you started with 200 grams of Nitrogen15 and now have 25 grams, how much of the Nitrogen15 decayed into daughter isotope?
175 grams
If you have 50 grams of Carbon14, and each half-life is 6000 years, how long will it take for it to decay to 12.5 grams of parent isotope and 37.5 grams of daughter isotope?
12,000 years
Define intrusion.
When magma breaks through layers of rock and new igneous rock forms.
What is a fossil?
The remains of a living thing.
What law says that the deeper the rock layer is the older it is?
A. Superposition
B. Crosscutting Relationships
C. Original Horizontality
D. Uniformitarianism
A. Superposition
See "Radiometric Dating" for 300 first.
You know the answer to "300" because of the Law of Conservation of Mass which states . . .
Matter cannot be created or destroyed; it only transfers/changes form
You have 1000 grams of Oxygen18. If 1/10 of a gram of it breaks down each year. How much daugther isotope will you have after 100 years?
10 grams of daughter isotope.
When did humans first occur (Chapter 9 - not on your test)?
1.8 million years ago.
What criteria must exist for something to be an index fossil? (HINT: There are 4)
Widespread, abundant, unique, only existed for a short period of time.
List 2 laws/principles we use in relative aging and 2 ways to figure out the absolute age of something.
Relative Aging: Superposition, Original Horizontality, Crosscutting Relationship
Absolute Aging: Varves, Radiometic Dating, Rate of Erosion, Rate of Deposition, Index Fossils
Free Points!
Math can be hard!
Do "Radiometric Dating" for 400 first
If you have 100 grams of daughter isotope, how much parent isotope do you have?
900 grams
What era are we currently in? (Chapter 9 -not on your test)
Cenozoic