Week 4

Question 1

Relative Dating

Answer 1

Putting events in order without any numerical age assigned to them.

Question 2

Absolute Dating

Answer 2

Calculating an exact date, we can do this with radiometric dating.

Question 3

Lithostratigraphy

Answer 3

Study of rock layers in sedimentary rocks.

Question 4

7 Principles of Relative Dating

Answer 4

Only work for sedimentary rocks

Superposition
Original Horizontality
Original Lateral Continuity
Cross Cutting Relationship
Principle of Inclusions
Principle of Unconformities
Principle of Faunal Succession

Question 5

Principle of Superposition

Answer 5

Oldest layer is on the bottom

Question 6

Principle of Original Horizontality

Answer 6

Sediments are deposited in horizontal layers, can be deformed later into folds or broken by faults.

Question 7

Principle of Original Lateral Continuity

Answer 7

Continuous layers, you can trace undeformed layers from one rock outcrop to another, even when some of the layers have been eroded.

Question 8

Principle of Cross Cutting Relationships

Answer 8

Any object that cuts across other object must be younger. Such as a dike.

Question 9

Principle of Inclusions

Answer 9

If you have one rock that is surrounded by another, the included is the oldest. Rock surrounded by others had to exist first.

Question 10

Principle of Unconformities

Answer 10

Rocks above an unconformity are younger than the rocks below. Unconformities mean there is time missing from the rock record.

Question 11

Principle of Faunal Succession

Answer 11

Animals evolve and go extinct never to return again. Extinction is forever. Extinct animals only appear in rocks that formed when it was alive.

Question 12

Biostratigraphy

Answer 12

Using fossils to tell time

Question 13

Index fossils

Answer 13

Useful for correlating rocks of the same age

Widespread geographically

Existed for a short range of geologic time

Question 14

Atoms

Answer 14

smallest unit of an element that still retains the properties of that element.

Question 15

The number of ____ in an atom determine what an element is.

Answer 15

The number of protons in an atom determine what an element is.

Question 16

Isotopes

Answer 16

atoms with differing amount of neutrons (hence differing mass numbers) but the same number of protons.

Question 17

____ isotopes do not spontaneously break down.

Answer 17

Stable isotopes do not spontaneously break down.

Question 18

____ isotopes break down over time.

Answer 18

Radioactive isotopes break down over time.

Question 19

Radiometric dating is based on

Answer 19

known rates of radioactive decay to estimate the age of geologic samples.

Question 20

Radiometric dating is measured using the ___ ___: the amount of time it takes for the sample to break down.

Answer 20

Radiometric dating is measured using the half life: the amount of time it takes for the sample to break down.

Question 21

Do atoms decay at a constant rate?

Answer 21

No, we can only get averages.

Question 22

In order to use radiometric dating there must be measurable quantities of

Answer 22

parent and daughter in the rock.

Question 23

Is carbon an appropriate isotope for dating dinosaurs?

Answer 23

No, it’s life is too short and it can’t be measured reliably.

Question 24

Are sedimentary or igneous rocks more appropriate for radiometric dating? Why?

Answer 24

Igneous rock is made up of one material, it is better for this kind of dating. Sedimentary rock is not as accurate because it’s made up of multiple minerals thus we can’t get an accurate reading on the rock as a whole.

Question 25

Why can’t we use radiometric dating on fossils?

Answer 25

Because we would then be dating carbon, and there’s not enough of it left to get an accurate reading.

Question 26

Paleontologist

Answer 26

A person who studies all manner of ancient life EXCEPT PEOPLE.

Question 27

What is a fossil and what types of fossils are there?

Answer 27

A fossil is preserved evidence of ancient life.

There are trace fossils and body fossils.

Trace fossils are evidence of behaviour. Like burrows, worm trails, or footprints.

Body fossils are the actual physical remains of something that lived once upon a time.

Question 28

Taphonomy

Answer 28

Study of everything that happens between death and discovery, this can take place over millions of years!

Question 29

When the fossil was buried determines

Answer 29

the quality of the fossil. A delayed burial will reduce the quality of the fossil whereas rapid burial will give us a high quality fossil.