Geologic Time Scale

Question 1

the change in the characteristics of a species over several generations; simply put, it is change over time

Answer 1

evolution

Question 2

author of “On the Origin of Species”, developed the theory of natural selection

Answer 2

Charles Darwin

Question 3

refers to the process where over long periods of time, helpful variations can appear in a species, while “unfavorable” ones disappear

Answer 3

natural selection

Question 4

divides up the history of the earth based on life forms that have existed during specific times

Answer 4

geological time scale

Question 5

a unit or division of geological time

Answer 5

geochronological units

Question 6

the longest subdivision; based on the abundance of certain fossils

Answer 6

eons

Question 7

second largest subdivision; marked by the major changes in the fossil record

Answer 7

eras

Question 8

based on the types of life existing at the time

Answer 8

periods

Question 9

shortest subdivision; marked by differences in life forms and can vary from continent to continent

Answer 9

epochs

Question 10

a method used to determine the age of an object based on the known decay rate of radioactive isotopes

Answer 10

radiometric dating

Question 11

determines the order of past events without necessarily determining the age of objects

Answer 11

relative dating

Question 12

also known as radiocarbon dating, a type of radiometric dating that determines the age of an organic material by measuring the radioactivity of its carbon content

Answer 12

carbon dating

Question 13

the time on earth when it is still forming so no fossils or records or life are found in this eon

Answer 13

Hadean Eon

Question 14

starts when the earth started to cool down, cyanobacteria started to thrive

Answer 14

Archean Eon (archea = ancient)

Question 15

around this time, photosynthetic bacteria spewed tons of oxygen into the atmosphere which gave rise to the first complex life forms (Charnia and Dickinsonia)

Answer 15

Proterozoic Eon

Question 16

it means current; the now

Answer 16

Phanerozoic Eon

Question 17

The Hadean, Archean, and Proterozoic Eon make up the _______ Eon.

Answer 17

Precambrian Eon

Question 18

is the oldest era, the early life forms thrived in water

Answer 18

Paleozoic Era

Question 19

explosion of life, life starts in water, marine invertebrates (trilobites and brachiopods) were dominant, supercontinent Gondwana forms near the South Pole (present-day Florida)

Answer 19

Cambrian

Question 20

1st animals with bones appeared, a very cold time on earth; the first mass extinction happened due to the ice caps in present-day Africa, Gondwana, Baltica, Siberia, and Laurentia were the four main continents

Answer 20

Ordovician

Question 21

first land plants and animals appeared, Laurentia collides with Baltica and closes the lapetus Sea, first millipede fossils and sea scorpions were found in this period

Answer 21

Silurian

Question 22

age of the fish, pre-Pangea forms, present-day Arctic Canada was at the equator and hardwoods began to grow; amphibians, evergreens, and ferns appear

Answer 22

Devonian

Question 23

first seed plants appeared, North America is covered by shallow seas; bryzoa, brachiopods, and blastoids flourished

Answer 23

Mississippian

Question 24

modern North America begins to form, ice covers the Southern hemisphere and coal swamps formed along the equator; lizard and winged insects first appeared

Answer 24

Pennsylvanian

Question 25

marks the last period of the Paleozoic, Pangea forms, the Appalachian mountain range rises, the deadliest mass extinction called the "Permian-Triassic Extinction" occurred that wiped out 95% of life on Earth

Answer 25

Permian

Question 26

dinosaurs dominated this era, ______ means 'middle life'

Answer 26

Mesozoic Era

Question 27

first dinosaurs appeared; first mammals (small rodents) appeared; after the mass extinction, life and fauna needed to re-diversify; rocky mountains formed; first turtle fossils were found from this period; Pangea breaks apart

Answer 27

Triassic

Question 28

Pangea was still breaking apart; the "Golden age of dinosaurs"; the first birds appeared; North America continued to shift away from Africa

Answer 28

Jurassic

Question 29

T-Rex flourished; first snakes and primates appeared; first flowering plants; deciduous trees; the 5th mass extinction (Cretaceous-Paleogene extinction) caused all the dinosaurs to be extinct

Answer 29

Cretaceous

Question 30

the earth's current geological era, also known as the "age of the mammals"

Answer 30

Cenozoic Era

Question 31

first horses appeared and tropical plants dominated the land

Answer 31

Paleocene (under tertiary)

Question 32

grasses spread and large mammals thrived

Answer 32

Eocene (under tertiary)

Question 33

dogs, cats, and apes appeared

Answer 33

Oligocene (under tertiary)

Question 34

horses, mastodons, camels, and tigers roamed free

Answer 34

Miocene (under tertiary)

Question 35

hominids developed and the Grand Canyon was formed

Answer 35

Pliocene (under tertiary)

Question 36

modern humans developed; the last ice age happened

Answer 36

Pleistocene (under quaternary)

Question 37

humans flourish; one that we are currently living in

Answer 37

Holocene (under quaternary)