Geologic Time Scale & Age of Earth Flashcards Preview

Earth Science > Geologic Time Scale & Age of Earth > Flashcards

Flashcards in Geologic Time Scale & Age of Earth Deck (64)
Loading flashcards...
1

______ time puts numbers and dates on things

absolute

2

The geologic time scale is a way of ________ the different time periods - and the whole time the earth has been in existence.

organizing

3

The geologic time scale is a visual ________ of geologic time

representation

4

What is the geologic time scale?

a visual representation of geologic time

5

The geologic time scale is based on...

the succession of rock layers

6

The geologic time scale is divided into:

Eons-> Eras -> Periods -> Epochs

7

What is the Precambrian supereon?

the period of time on the Earth before there was any life on Earth

8

About 600 million years ago we began which eon?

Phanerozoic

9

The Phanerozoic eon includes which three eras?

Paleozoic, Mesozoic, Cenozoic

10

The Paleozoic era was marked by...

single cell life that developed into mostly ocean-dwelling creatures

11

The Paleozoic era was marked by ______ cell life that developed into mostly ocean- ______ creatures.

single, ocean

12

The Mesozoic Era was the Age of the...

Dinosaurs

13

The Cenozoic Era has been named the Age of the...

Mammals

14

which eon are we currently in?

the Phanerozoic eon

15

which era are we currently in?

the Cenozoic era

16

What are Eras further divided up into?

Periods

17

how long to periods last?

millions of years

18

The starting and ending dates of most periods are based on...

fossil groups

19

Some period boundaries are marked by ______

extinctions.

20

Periods are further subdivided into...

epochs

21

Some of the earliest attempts at estimating the Age of the Earth are based on...

sedimentation, and thickness of the strata

22

The earliest attempts at estimating the Age of the Earth looked at a series of rock _____ and figuring out how long it might have taken to ______ all of those rock units.

units, deposit

23

To conduct accurate estimations of the age of the earth based on sedimentation you would need to assume that there was...

a constant record of deposition and no weathering/erosion

24

Sir Halley came up with a method to estimate the age of the earth by looking at...

the oceans, and how much salt is dissolved in the oceans.

25

Sir Halleys theory is that if you could assume that the oceans were originally ________, how long would it have taken for them to accumulate the amount of _____ that they have today

freshwater, salt

26

By using Sir Halley's method what was the estimated age of the earth?

90 million years.

27

What were the flaws of Sir Halley's method?

- you need to assume that the ocean started at 0% salinity (which isn't necessarily true)

- you need to assume that the salt content doesn't vary (which isn't necessarily true: salt content can be lost through tectonic, biologic processes)

28

How can salt content be lost in the ocean?

through biologic, tectonic processes

29

What was Darwin's estimate of the age of the earth based on?

the time it would be necessary toe rod a particular mountain range in Europe

30

How old did Darwin estimate the Earth to be?

300 million years old