The Geologic Time Scale

Question 1

the third and last period of the Mesozoic, spanning from 145 mya to 66 mya; first appearance of flowering plants which resulted to insects’ evolution to pollinate them; Tyrannosaurus rex rawrawrawr

Answer 1

the Cretaceous Period

fun fact: Cretaceous comes from the Latin word “creta” which means chalk—it’s named for the large quantities of chalk rock laid down at this time in Western Europe; it ended at the Cretaceous-Paleogene Extinction Event (K-T/K-Pg) 66 mya, the last of the five major mass extinction events, which was caused by a massive asteroid, killing 75% of the species including all non-avian dinosaurs

Question 2

the third and latest period of the Cenozoic, spanning from 2.58 mya to the present; divided into two epochs; marked by the several ice ages, the development of modern ecosystems, and the evolution of modern humans

Answer 2

the Quarternary Period

Question 3

the six internationally accepted periods of the Paleozoic Era in chronological order

Answer 3

the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian Periods

fun fact: North American geologists divide the Carboniferous Period, the fifth period, into two, making Paleozoic’s periods seven

Question 4

the first period of the Cenozoic, spanning from 66 mya to 23 mya; divided into 3 epochs; mammals started to diversify as dinosaurs left a lot of ecological niches

Answer 4

the Paleogene Period

fun fact: it means “old/ancient-born”—it is the first of the two divisions of the original Tertiary Period

Question 5

the first epoch of the Paleogene, spanning from 66 mya to 56 mya; beginning of modern life forms following the K-T
Boundary Extinction; age of mammals began, and grasslands spread

Answer 5

the Paleocene Epoch

fun fact: it comes from the Greek words “paleo,” meaning ancient, and “kainos,” meaning recent or new—it is the oldest epoch in the new period and era

Question 6

the first epoch of the Neogene, spanning from 23 mya to 5.3 mya; horses, rhinoceri, and elephants flourished

Answer 6

the Miocene Epoch

fun fact: it means “less recent”—though this was originally chosen as its name because the epoch saw a decline in marine biodiversity, this also translates to it being the older of the two epochs of the Neogene

Question 7

the three Precambrian eons in chronological order

Answer 7

the Hadean, Archean, and Proterozoic Eons

Question 8

the second period of the Paleozoic, spanning from 485 mya to 444 mya; characterized by the invertebrate’s domination of the oceans, and the plant’s colonization of the land

Answer 8

the Ordovician Period

fun fact: it ended at the Ordovician-Silurian Extinction Event 444 mya, the first of the five major mass extinction events, where 86% of the species at the time died

Question 9

the four major divisions of the geologic time scale

Answer 9

eon, era, period, epoch

Question 10

the second and last epoch of the Neogene, spanning from 5.3 mya to 2.58 mya; a time of global cooling after the warmer Miocene; first appearance of hominids, the ancestors of modern humans

Answer 10

the Pliocene Epoch

fun fact: it means “more recent”—it’s the younger of the two epochs of the Neogene

Question 11

the smallest division of the geologic time scale characterized by distinct organisms

Answer 11

epoch

Question 12

the eon spanning from 2.5 bya to 541 mya; characterized by the appearance of the earliest forms of life; cyanobacteria existed (w/o oxygen) and oxygenated the Earth

Answer 12

the Proterozoic Eon

fun fact: it means “earlier life”—the Proterozoic preceded the Paleozoic, in which life started to bloom

Question 13

the second of latest epoch of the Quarternary, spanning from 11.7 kya to the present; hoomans

Answer 13

the Holocene Epoch

fun fact: it means “entirely recent”

Question 14

a division in an eon that spans time periods of tens to hundreds of millions of years

Answer 14

era

Question 15

the periods of the Cenozoic Era in chronological order

Answer 15

the Paleogene, Neogene, and Quarternary Periods

fun fact: the Cenozoic originally only had two periods, Tertiary and Quarternary, until Tertiary was divided into two, the Paleogene and Neogene

Question 16

the current eon, which started at the Cambrian explosion in the Paleozoic Era

Answer 16

the Phanerozoic Eon

fun fact: it means “visible life”—there are evidences proving that life already existed in the Precambrian, but life only truly flourished during the Phanerozoic

Question 17

the fourth period of the Paleozoic, spanning from 419 mya to 359 mya; also called as the golden age of fish due to their diversification; land plants became common; vascular plants (club mosses and ferns) developed

Answer 17

the Devonian Period

fun fact: the Late Devonian Extinctions, which happened 375 - 359 mya and was the second of the five major mass extinction events, consisted of several waves of organismal disappearance that collectively killed ~75% of Devonian species and ultimately ended the period

Question 18

the second period of the Cenozoic, spanning from 23 mya to 2.58 mya; divided into 2 epochs; mammals continued to diversify; the first humans appeared; the cooling trend that started in the late Paleogene continued, leading to the onset of ice ages

Answer 18

the Neogene Period

fun fact: it means “newborn”—it is the second of the two divisions of the original Tertiary Period

Question 19

the age of Earth

Answer 19

4.6 billion years old

Question 20

the three eras of the Phanerozoic in chronological order

Answer 20

the Paleozoic, Mesozoic, and Cenozoic Eras

Question 21

the eon spanning from the formation of Earth 4.5 - 4.6 bya to 4 bya; characterized by very high temperatures

Answer 21

the Hadean Eon

fun fact: it was named after the Greek god of the underworld—Earth was literally hellish during this eon

Question 22

one of Phanerozoic’s Eon’s eras, spanning from 252 mya to 66 mya; the age of reptiles; divided into three periods; the carbon and oxygen concentrations in the atmosphere was very high

Answer 22

the Mesozoic Era

fun fact: it means “middle life”—the Mesozoic is the second of the three eras of the Phanerozoic Eon, in which dinosaurs dominated the Earth

Question 23

the periods of the Mesozoic Era in chronological order

Answer 23

the Triassic, Jurassic, and Cretaceous Periods

Question 24

the third and last epoch of the Paleogene, spanning from 34 mya to 23 mya; characterized by the rise of horses, antelopes, cats, oreodonts; a sudden decrease in earth’s temperature caused a permanent ice cap to form over Antarctica

Answer 24

the Oligocene Epoch

fun fact: it means “little recent”—the Oligocene has a low biodiversity compared to the Eocene, caused by the global cooling

Question 25

the fifth period of the Paleozoic, spanning from 359 mya to 299 mya; also called as the golden age of amphibians as several fish moved to and dominated the land; the first appearance of winged reptiles and winged insects

Answer 25

the Carboniferous Period

fun fact: it means “carbon-bearing”—it is named after the large underground coal deposits that date to it due to the Carboniferous Rainforest Collapse caused by the formation of the Pangaea; it is divided by North American geologists into two: the Pennsylvanian and Mississippian Periods

Question 26

the largest division of the geologic time scale

Answer 26

eon

Question 27

the first period of the Paleozoic, spanning from 541 mya to 485 mya; usually proceeded by the word “explosion” due to the sudden burst of biodiversity

Answer 27

the Cambrian Period

Question 28

the first period of the Mesozoic, spanning from 252 mya to 201 mya; characterized by the appearance of the earliest dinosaurs and true mammals; huge seed ferns and
conifers dominated the forest; Pangaea broke into two new continents Laurasia and Gondwanaland

Answer 28

the Triassic Period

fun fact: it ended at the End-Triassic Extinction Event 201 mya, the fourth of the five major mass extinction events, where 80% of the species at the time died

Question 29

division of geologic history that spans no more than one hundred million years

Answer 29

period

Question 30

the epochs of the Quarternary Period in chronological order

Answer 30

the Pleistocene and Holocene Epochs

Question 31

one of Phanerozoic Eon’s eras, spanning from 541 mya to 252 mya; characterized by the first surge of life; divided into six periods [seven if you’re North American (you’re not)]

Answer 31

the Paleozoic Era

fun fact: it means “old/ancient life”—it is the first of the three eras of the Phanerozoic Eon

Question 32

the amount of time (in percentage) the pre-Cambrian eons take up in the geologic time scale

Answer 32

~88%

Question 33

the epochs of the Paleogene Period in chronological order

Answer 33

the Paleocene, Eocene, and the Oligocene Epochs

Question 34

the epochs of the Neogene Period in chronological order

Answer 34

the Miocene and Pliocene Epochs

Question 35

the sixth and final period of the Paleozoic, spanning from 299 mya to 252 mya; formation of the supercontinent Pangaea; amphibians decline while reptiles and insects increase in population and diversity; the first appearance of mammal-like reptiles appear

Answer 35

the Permian Period

fun fact: it ended at the Permian-Triassic Extinction Event (or the Great Dying) 252 mya, the third and biggest of the five major mass extinction events—~96% of the extant species at the time were eliminated

Question 36

the third and latest era of the Phanerozoic Eon, spanning from 66 mya to the present; also called as the age of mammals; divided into 3 periods which are further divided into a total of 7 epochs

Answer 36

the Cenozoic Era

fun fact: it means recent life

Question 37

the first epoch of the Quarternary, spanning from 2.58 mya to 11.7 kya; mammals successfully colonized all environments; early humans continued to evolve as this epoch is also called the Paleolithic or Old Stone Age in archaeology

Answer 37

the Pleistocene Epoch

fun fact: it means “most recent”

Question 38

the second epoch of the Paleogene, spanning from 56 mya to 34 mya; global temperatures increased by 5–8 °C (Paleocene-Eocene Thermal Maximum or PETM)

Answer 38

the Eocene Epoch

fun fact: it means “dawn of the recent”—the Eocene marked the rise and diversification of many modern groups of fauna and flora

Question 39

the second and likely the most popular period of the Mesozoic, spanning from 201 mya to 145 mya; also called as the Golden Age of Dinosaurs; earliest birds evolved from reptiles; also characterized by the intense volcanic activity

Answer 39

the Jurassic Period

Question 40

the eon spanning from 4 bya to 2.5 bya; continental plates began to form in this eon due to Earth’s crust cooling enough; the atmosphere composed of methane, ammonia, and other toxic gases

Answer 40

the Archean Eon

fun fact: it means “at or near the beginning”—the Archean marked the start of the isotopic age of the earliest rocks

Question 41

the third and shortest period of the Paleozoic, spanning from 444 mya to 419 mya; also called as the golden age of cephalopods and brachiopods due to lack of true predators; the first land plants developed, and the first arthropods
ventured onto land

Answer 41

the Silurian Period