Chapter 21 - Personaly Created Questions

Question 1

Hey! Just a friendly note:

Answer 1

ROCKS GET RECYCLED!

Question 2

What is the purpose of the Geologic time scale and the Rock Record?

Answer 2

Scientists are able to recall earth’s history and allows scientists to find the relationships between geologic events and past conditions.

Question 3

What are the 4 units (in order from longest to shortest) in the Geological time scale?

Answer 3

1) Eons
2) Era
3) Period
4) Epoch

Question 4

What are the 4 Eons? (Try to do oldest to youngest)

Answer 4

Hadean (oldest), Archean (single celled life), Proterozoic (more advanced), Phanerozoic

Question 5

The first 3 Eons (Hadean, Archean, Proterozoic) make up 90% of geological time. What are they called?

Answer 5

Precambrian

Question 6

What are Eras biased on? It’s okay if you don’t know.

Answer 6

What fossils were found at that time/area, and difference in life forms

Question 7

What are the three Eras, and what do they mean?

Answer 7

Palozoic (Old life), Mesozoic (Middle life), and Cenozoic (recent life)

Question 8

Of the 4 units in the Geologic time scale, which ones of each do we live in?

Answer 8

Eon: Phanerozic
Era: Cenozoic
Period: Quarternary
Epoch: Holocene

Question 9

What large event usually signifies a new era?

Answer 9

Some form of extinction

Question 10

About how old is earth (according to scientists).

Answer 10

4.6 bya

Question 11

Who came up with uniformitarianism? Don’t need to know, just extra

Answer 11

James Hutton

Question 12

Some extra notes:

Answer 12

Scientists can determine the layer which rocks have formed because the oldest layers are at the bottom. Once there is an order for the rocks, they can see the relative age of the rock record.

Question 13

When you are describing the relative age of something, what words should you use?

Answer 13

Younger and older

Question 14

In basic terms, what is Origional Horizontality?

Answer 14

If something has not acted on a rock layer, it will stay horizontal. Likewise, if some layer is not horizontal, something has acted on it.

Question 15

What is one of the most common reasons rock layers shift or angle?

Answer 15

The movement of tectonic plates

Question 16

What does superposition mean?

Answer 16

It basically states that the rocks on the bottom of the rock record are older than the rocks above it. Layers above are younger, and layers below it are older!

Question 17

What does cross-cutting relationship mean?

Answer 17

“Fault/body of rock/place where tectonic plates meet/something that cuts across another rock is younger than the rock it cuts through”

EXAMPLE: You can’t cut through something if it is not there!

Question 18

What does the principle of inclusions state?

Answer 18

Any fragment in a layer of rock must be older than the rock surrounding it. This is because the fragment has to be there before the stuff around it can form.

Question 19

What is an Unconformity?

Answer 19

Its basically a break in the geologic record!

Question 20

What is correlation?

Answer 20

The matching of rocks in one place to the rocks in another place (possibly due to similar rocks or fossils). For example, the grand staircase!

Question 21

How many principles of determine relative age are there?

Answer 21

7.

Question 22

What are the 3 types of unconformities? What do they mean?

Answer 22

Disconformities are layers of sedimentary rock on top of layers of eroded sed. rock. NONconformities are the opposite, sed. On top of igneous or metamorphic. Angular unconformities are sed layers on top of tilted layers

Question 23

How much percent of the history of the earth have the humans existed?

Answer 23

0.000065%!!! That’s 4 Zeros!!

Question 24

What is a key bed?

Answer 24

Any layer that serves as a MARKER. Easy to recognize (from place to place?)

Question 25

What is a fossil correlation? How is it like a keybed?

Answer 25

“Paleontologists can use fossils to determine relative age of the rock layers in which fossils are located” Kind of like a key bed, where a layer of fossil can be compared to similar layers in other places.

Question 26

Extra: what’s an index fossil?

Answer 26

“A fossil used to establish the age of rock layers because it is distinct, abundant, widespread, and existed for only a short span for geologic time” correlation = fossil correlation
Key-bed= index fossil

Question 27

What type of rocks do absolute age dating tactics usually deal with?

Answer 27

Igneous and metamorphic. Not sedimentary because it’s made up of too many different kinds of rocks.

Question 28

What does absolute age dating give to rocks?

Answer 28

A numeric value

Question 29

How does radioactive decay WORK?

Answer 29

A ton of radioactive atoms and isotopes, over time, release particles and energy, slowly creating a non-radioactive element.

Question 30

What does Uranium 238 turn into?

Answer 30

Lead 206

Question 31

How much does the rate of decay change during the decay process (horrible wording)

Answer 31

It doesn’t. The rate of decay for a rock always stays CONSTANT, despite physical pressures and changes. Used to determine absolute age

Question 32

NOTE:

Answer 32

Radioactive decay and radiometric dating are 2 different things.

Question 33

What is the radioactive isotope / original isotope in an element called in radiometric dating?

Answer 33

The Parent Isotope

Question 34

Then, as time goes on, what does the parent isotope decay into?

Answer 34

The daughter isotope

Question 35

Comparing the ratio of parent isotopes to daughter isotopes determines what?

Answer 35

It determines the absolute age of the rock

Question 36

Note : 384

Answer 36

A daughter isotope is stable, while a parent isotope is radioactive