Review Questions

Chapter 8: Relative Dating, Absolute Dating, Fossils

This principle states that geologic processes are the same today as

they were in the past but the RATES of the processes vary over time

Uniformitarianism

This branch of Earth Science studies the history

of the Earth

Earth Science

What does a Paleontologist study?

Fossils

When you determine whether an object or event is older or

younger than other objects/events, you are finding the object’s ___________ Age.

Relative

This law states that younger rocks lie above

older rocks in undisturbed rock layers.Superposition

A break in the earth’s crust along which blocks of crust

slide relative to one another

Fault

Molten rock from Earth’s interior that squeezes into

existing rock layers and cools

Intrusion

This type of rock disturbance occurs when

rock layers bend and buckle from Earth’s

internal forcesFolding

This disturbance occurs when internal forces in the

earth slant rock layers without folding them

Tilting

Hardened tree sap that sometimes has the

preserved remains of insects

Amber

The number of years an object has existed

Absolute Age

Remains or traces of animals or plants that lived

in past geologic times

Fossils

This occurs when an organism’s tissues are

completely replaced by minerals

Petrification

Any naturally preserved evidence of an animal’s

activity

Trace Fossil

A type of trace fossil that is made from preserved

animal feces or dung & can provide information about the habits/diet of animals

that left themCoprolite

An empty space/cavity in rock where a plant or

animal was buried

Mold

A replica of an object that is created when sediment fills a mold and becomes

rock

Cast

The boundary between a set of tilted rock layers and

a set of horizontal layers

Angular Unconformity

Atoms of the same element that have

different numbers of neutrons

Isotopes

Fossils of organisms that lived during a short, well-defined time span and are only found in rock layers of

a particular geologic ageIndex Fossils

The earth’s age, according to geologists

4.6 Billion years old

The law that states that faults/intrusions are

always younger than the rock layers they cut

throughLaw of Crosscutting

Relationships

Saying one rock is older or younger than another rock

but not saying its age in years

Relative Age

Principle that states that sedimentary rocks left

undisturbed will remain in horizontal layers

Principle of Original Horizontality

A break in the geologic rock record

Unconformity

List 3 methods of absolute dating besides Radiometric

DatingRates of Erosion

Rates of DepositionVarve Count

List two reasons Radiometric Dating is the

most accurate methodDoesn’t depend on

EnvironmentRates don’t vary over time

The original radioactive isotope

Parent Isotope

The newly formed, more stable isotope that forms during radioactive decay

Daughter Isotope

The time it takes for ½ the mass of parent isotope to

decay into its daughter isotopeHalf Life

If you have 16 g of radioactive parent isotope,

how much parent/daughter isotope will you have after 3 half

lives?2 g of Parent

14 g of Daughter

This parent isotope decays into Lead-206, has a half

life of 4.5 billion years, and is used to date rock that is

really old

Uranium 238

This parent isotope decays into Nitrogen-14, has a half

life of 5,730 years, and is used to date rock that is

relatively young

Carbon-14

Sue was found in this state

South Dakota

Sue was the most _______ T.rex ever found

Complete

WHO was Sue the T.rex named after?

The woman who found her

Who bought Sue and for how much?

Chicago’s Field Museum$8 Million