Chapter 3 - Time and Geology

Question 1

actual geologic dating

Answer 1

approximate actual age of rocks using radioactive dating

Question 2

alpha particle

Answer 2

positively charged ions of the element helium that have an atomic weight of 4 and an atomic number of 2

Question 3

Archean Eon

Answer 3

4000-2500 Ma

Question 4

atom

Answer 4

smallest particle of matter that can exist as a chemical element

Question 5

atomic mass

Answer 5

approximately equals the sum of the masses of its protons and neutrons

Question 6

atomic number

Answer 6

number of protons in a nucleus of a substance

Question 7

bentonite

Answer 7

weathered volcanic ash

Question 8

beta particle

Answer 8

an electron that is releases when a neutron splits into a proton and an electron

Question 9

Cambrian System

Answer 9

542-488 Ma

Question 10

Cenozoic Era

Answer 10

“recent life” of the Phanerozoic Eon

Question 11

Cretaceous System

Answer 11

145-65 Ma

Question 12

daughter element

Answer 12

formed from the radioactive parent element

Question 13

electron

Answer 13

neutral charges

Question 14

element

Answer 14

oxygen, silicon, sodium, and so on

Question 15

eon

Answer 15

largest increments of time: Hadean, Archean (4Ga), Proterozoic (2500 Ma), and Phanerozoic (542 Ma)

Question 16

epoch

Answer 16

periods are divided into epochs

Question 17

era

Answer 17

eons are divided into eras; eras into periods; periods into epochs; epochs into ages

Question 18

fission tracks

Answer 18

tunnels in a sample produced when high-energy particles from uranium nuclei were fired off during spontaneous fission

Question 19

gamma radiation

Answer 19

invisible electromagnetic waves that have extremely high frequencies

Question 20

geochronolgy

Answer 20

science of determining the age of rocks

Question 21

Hadean Eon

Answer 21

greater then 4 Ga

Question 22

half-life

Answer 22

time required for half of the original quantity of atoms in a sample to decay

Question 23

isotope

Answer 23

two or more varieties of the same element that have identical atomic numbers and chemical properties, but differ in mass numbers because they have a varying number of neutrons in the nucleus

Question 24

Jurassic System

Answer 24

200-145 Ma

Question 25

Mesozoic Era

Answer 25

"middle life" of the Phanerozoic Eon

Question 26

neutron

Answer 26

electrically neutral

Question 27

Paleozoic Era

Answer 27

"ancient life" of the Phanerozoic Eon

Question 28

parent element

Answer 28

the radioactive element that gives birth to daughter elements

Question 29

period

Answer 29

eras are divided into periods

Question 30

Phanerozoic Eon

Answer 30

542 Ma to present

Question 31

Proterozoic Eon

Answer 31

2500-542 Ma

Question 32

proton

Answer 32

carries a positive electrical charge

Question 33

Quaternary System

Answer 33

1.8 Ma to present

Question 34

radioactivity

Answer 34

the release of particles of energy

Question 35

relative geologic dating

Answer 35

places geologic events, and the rocks representing those events in sequence

Question 36

series

Answer 36

time-rock unit equal to an epoch

Question 37

Silurian System

Answer 37

447-416 Ma

Question 38

stage

Answer 38

time-rock unit equal to an age

Question 39

system

Answer 39

time-rock unit equal to a period

Question 40

time-rock unit ( = chronostratigraphic unit)

Answer 40

bodies of rock formed during each time unit

Question 41

time unit (= geochronologic unit)

Answer 41

eras, periods, epochs and ages

Question 42

Triassic System

Answer 42

251-200 Ma

Question 43

uranium-238

Answer 43

parent of lead-206; half-life of 4.47 billion years

Question 44

lead-206

Answer 44

daughter of uranium-238;

Question 45

uranium-235

Answer 45

parent of lead-207; half-life of 704 million years

Question 46

lead-207

Answer 46

daughter of uranium-235;

Question 47

thorium-232

Answer 47

parent of lead-208;

Question 48

lead-208

Answer 48

daughter of thorium-232;

Question 49

potassium-40

Answer 49

parent of argon-40; half-life of 1.251 billion years

Question 50

argon-40

Answer 50

daughter of potassium-40;

Question 51

rubidium-87

Answer 51

parent of strontium-87; half-life of 48.8 billion years

Question 52

strontium-87

Answer 52

daughter of rubidium-87;

Question 53

carbon-14

Answer 53

parent of nitrogen-14; half-life of 5730 year

Question 54

nitrogen-14

Answer 54

daughter of carbon-14;