History of the EarthHistory of the EarthToo much time on my hands.

Let’s go to the fossil record.

That’s some radioactive

decay you have on.

Take up your super

positions.

Correlate the correlation.

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Final Jeopardy

What are the necessary conditions for a once living organism to turn into a

fossil?• Organisms need to be buried quickly to avoid decay• Organisms usually need hard parts that can be imprinted

into the rock layers

Is the Principle of Superposition more related to relative dating or absolute dating? Why?

Relative Dating. The principle tells us position of the rock layers compared to

other layers. It does not tell us their absolute age.

120 mya

> 120 mya

< 120 mya

What is the principle of What is the principle of horizontality?horizontality?

The force of gravity does the work to lay down sediments in flat layers. Eventually, the flat layers of sediment may turn into sedimentary rock. This is similar to how we see the horizon.

Traces, imprints, or the remains of once-living things are called…

Fossils

Explain uniformitarianism

• Uniformitarianism states that Earth slow processes that happen today are similar to those that occured in the past

Organize these layers in the events in which they occurred. (Oldest to Youngest)

D-C-B-AD-C-B-A

D

C

B

A

Bonus $100

The principle that cut these layers?

The Principle of Crosscutting

What are the three ingredients that make a good index fossil?

1.Hard parts2.Lived abundantly and

widespread on the Earth3.Lived for a short period

of time

Bonus 200: Why were eurypterids not good index

fossils?

Although they had both hard parts and were

widespread on the Earth. They lived during many

periods of time.

Bonus Question

Compare and Contrast Compare and Contrast a trace fossil with a regular fossila trace fossil with a regular fossil

Both are the remains, imprints, or traces of once-living organisms preserved in rocks

Only trace fossils provide tracks and other evidence of animal activity

Why do we study fossils?Answer questions like:When did life begin?

What did ancient organisms look like? How did they live?

Don’t theyAlso help you

date rock layers?!

What is the principle of lateral continuity?Rock layers will continue sideways in all

directionsIf layers are missing in the middle, we can

assume that they were once connected.

What is the principle of inclusions?As younger rocks form, pieces older rocks are

included in them.

clasts

xenoliths

What is the half-life of an isotope?

The half life refers to the time it takes for radioactive material, the isotope, to “ half ” or 50% decay.

Material usually has many “half lives” before it completely decays.

Bonus 200:What is the half life of

Carbon-14

Every 5,730 years before ½ of Carbon-14 material

decays.

Bonus

What is the Principle of Superposition?

In layers of undisturbed rock the youngest rock are on top and the oldest rocks are

on the bottom.

Older

Younger

Normally, the three particles of the atom work to _________ the

overall charge and _____________ of the atom.

balancestabilize

Occasionally, scientists find the original remains of creatures. What substance or conditions have been known to preserve

organisms?

• Amber

• Tar

• IceDon’t even think about

touching my DNA!

What are the building blocks of all matter whether its living or

non-living?

The mighty little

ATOM

Geologists estimate the Earth to be approximately how many

millions of years old?

4,600 millionOr

4.6 billion

What is the principle of faunal succession?

Fossils can be used to correlate and date rock layers

If you were studying the age of rock layers and did not have access to absolute dating methods, how could you get an approximate age of the rock layers?

• Relative dating methods, like using the principle of superposition and other principles.

When rock layers are spread over a large area, we match them up.

What’s that called? Correlating rock layers

What is usually unstable parent material or daughter product?

Parent material

When unstable atoms break down, what’s the process called?

Radioactive decay

What is an unconformity in the rock layers?

• When rock layers do not follow the normal relative age order, according to the 6 principles. They can’t be relatively correlated.

-Bonus 300-What is a angular

unconformity?

-Bonus 300-When younger layers of rock

form horizontally on top of the eroded and tilted layers.

Getting an accurate relative age is a problem.

Absolute dating is a process that uses Absolute dating is a process that uses the properties of the properties of ____________ in rocks and in rocks and

other materials, like petrified other materials, like petrified remains, to determine their ages.remains, to determine their ages.

atoms

What is the difference between a mold and a cast?

• A mold of a species is created when rock forms around the body and then the body decays.

• If sediment fills the mold and hardens a cast of the species is formed.

Final Jeopardy

Compare and Contrast: Relative Dating

And Absolute Dating

Final Jeopardy AnswerAbsolute and relative dating are both used to

calculate and understand the geologic and evolutionary history of the Earth. Relative dating uses rules like the Principle of Superposition, older layers on the bottom; newer layers on top, to arrive at a relative, not exact, age of Earth. By understanding unconformities, geologist can correlate rock layers to match when and where geologic events took place. Absolute dating is more of an exact science. It uses the radioactive decay of isotopes to calculate the age of a fossil and rock layer. Each isotopes has a half-life that scientist use to measure the age. Both absolute and relative dating work together to help scientists understand the history of the Earth.

Jeopardy does not contain all the information you need to know for the test. Continue to review your notes, class work, and/or the online PowerPoints

Our next area of study will be… PLATE TECTONICS!!

(Yes, that includes volcanoes.)