Geologic Time Scale

Question 1

the “calendar” for events in Earth history. It subdivides all time into named units of abstract time called—in descending order of duration—eons, eras, periods, epochs, and ages.

• chronological, relates rock and fossils

Answer 1

geologic time scale

Question 2

time span of all 4 eons on earth

Answer 2

4.6 billion years

Question 3

eons on earth

Answer 3

hadean, archaean, proterozoic, phanerozoic

Question 4

informal division of Precambrian time occurring between about 4.6 billion and about 4.0 billion years ago. This Eon is characterized by Earth’s initial formation—from the accretion of dust and gases and the frequent collisions of larger planetesimals—and by the stabilization of its core and crust and the development of its atmosphere and oceans.

• enormous amounts of heat that likely prevented much of the rock from solidifying at the surface (hellish)
• calmed later on leading to the presence of carbohydrates, protein, lipids, and nucleic acid (due to meteors?)

Answer 4

hadean eon

Question 5

Eon

(4-2.5 billion years ago) methane droplets in the air shrouded the young Earth in a global haze. There was no oxygen gas on Earth. Oxygen was only in compounds such as water. Complex chemical reactions in the young oceans transformed carbon-containing molecules into simple, living cells that did not need oxygen to live. (Extremophiles, Archaean - those that thrived in harsh environments) Instead, they made energy out of sulfur and other elements.

• the rise of the 1st living things - archaea bacteria (prokaryotes)
• presence of cyanobacteria - They made gaseous, or free, oxygen from carbon dioxide, water, and sunlight—the process called photosynthesis. As cyanobacteria created more free oxygen, the amount of oxygen in the atmosphere reached one percent of today’s level, which is 21 percent

Answer 5

archaean eon

Question 6

eon (prototypes of life)

the younger of the two divisions of Precambrian time
- extended from 2.5 billion to 541 million years ago
- the atmosphere and oceans changed significantly.
- the fossil remains of bacteria and blue-green algae as well as the first oxygen-dependent animals, the Ediacara fauna.
- hosting the transition to an oxygenated atmosphere.
- the Great Oxygen Event, Snowball Earth, formation of the supercontinent Rodinia, and the evolution of eukaryotic cells and of multicellular organisms (bc of oxygenated atmosphere).

Answer 6

proterozoic eon

Question 7

occurred when cyanobacteria living in the oceans started producing oxygen through photosynthesis. As oxygen built up in the atmosphere anaerobic bacteria were killed leading to the Earth’s first mass extinction

Answer 7

the great oxygen event

Question 8

What possibly caused the snowball earth during proterozoic era

Answer 8

decline in the CO2 level (probably bc of cyanobactera), reduced concentration of greenhouse gases, such as methane and/or carbon dioxide, perturbations of Earth’s orbit, etc.

or

Possibly by a lowering of atmospheric greenhouse gases to near-present levels through tectonically-mediated rock weathering, when the Sun was considerably dimmer than present.

Question 9

defined as the supercontinent that existed in early Neoproterozoic time

Answer 9

rodinia

Question 10

The name means: “before the Cambrian period.” This old, but still common term was originally used to refer to the whole period of earth’s history before the formation of the oldest rocks with recognizable fossils in them.
- covers almost 90% of the entire history of the Earth. It has been divided into three eons: the Hadean, the Archean and the Proterozoic.
- only microfossils?

Answer 10

pre-cambrian era

Question 11

the eon of visible life
- evident life
- the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed. It covers 538.8 million years to the present

Answer 11

phanerozoic eon

Question 12

eras under phanerozoic eon

Answer 12

paleozoic, mesozoic, cenozoic

Question 13

era under phanerozoic eon

major interval of geologic time that began 541 million years ago with the Cambrian explosion and ended about 252 million years ago with the end-Permian extinction, the greatest extinction event in Earth history.
- the time when pangaea was formed
- takes its name from the Greek word for ancient life.
- began with the breakup of one supercontinent and the formation of another. Plants became widespread. And the first vertebrate animals colonized land

Answer 13

paleozoic era

Question 14

periods under paleozoic era

Answer 14

cambrian, ordovician, silurian, devonian, carboniferous, permian

Question 15

period under paleozoic era

part of the Paleozoic era, produced the most intense burst of evolution ever known.
- earliest time division of the Paleozoic Era, extending from 541 million to 485.4 million years ago.
- land plants had not yet evolved, so the terrestrial world was devoid of vegetation. However, in the oceans (underwater) many marine invertebrates, including sponges and brachiopods (lamp shells),
- ended by an extinction event (mostly invertibrates)

Answer 15

cambrian period

Question 16

the unparalleled emergence of organisms between 541 million and approximately 530 million years ago at the beginning of the Cambrian Period. The event was characterized by the appearance of many of the major phyla (between 20 and 35) that make up modern animal life.

• an extraordinary diversification of marine animals,

Answer 16

Cambrian explosion

Question 17

the second period of the Paleozoic Era. It began 485.4 million years ago, following the Cambrian Period, and ended 443.8 million years ago.

• This is best known for its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and conodonts (early vertebrates). More recently, tetrahedral spores that are similar to those of primitive land plants have been found, suggesting that plants invaded the land at this time.
• when invertebrates evolved, and vertebrates emerged from underwater
• jawless fish
• ended by the 1st extinction event in phanerozoic era

Answer 17

Ordovician period

Question 18

The extinction was a most likely a result of global cooling and reduced sea levels, which dramatically impacted the many marine species living in warm, shallow coastal waters. (probably due to the depletion of C02, too many plants)

the first of the “big five” major mass extinction events in Earth’s history,
- A major ice age is known to have occurred in the southern hemisphere and climates cooled worldwide.
- those that survived underwater adapted to walk

Answer 18

ordovician-silurian extinction

Question 19

period under paleozoic era

the third period of the Paleozoic Era. It began 443.8 million years ago and ended 419.2 million years ago
- first land plants, insects, and jawed fish

Answer 19

Silurian period

Question 20

period under paleozoic era

an interval of the Paleozoic Era that follows the Silurian Period and precedes the Carboniferous Period, spanning between about 419.2 million and 358.9 million years ago.
- age of fishes
- Late in the period the first four-legged amphibians appeared, indicating the colonization of land by vertebrates.
- first land animals
- ended with an extinction event
- cartilagenous fishes

Answer 20

devonian period

Question 21

A second mass extinction
- primarily affected the marine community
- dissolved oxygen in oceans decreased (bc kumonti autotrophs), prohibiting decay and allowing the preservation of organic matter, which then over time underwent through anaerobic respiration and became oil

Answer 21

late devonian extinction event

Question 22

period under paleozoic era
- is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period 358.9 million years ago (Mya), to the beginning of the Permian Period, 298.9 million years ago.
- “coal bearing”
- when moss and swamps underwent decomposition anaerobically, overtime turning into coal
- takes its name from large underground coal deposits that date to it.
- pangaea is forming
- first reptiles and large cartilaginous fishes appear
- evolution of lungs?
- age of amphibians?

Answer 22

carboniferous period

Question 23

period under paleozoic era

the last period of the Paleozoic Era. began 298.9 million years ago and ended 252.2 million years ago, extending from the close of the Carboniferous Period to the outset of the Triassic Period.
- Earth’s crustal plates formed a single, massive continent called Pangaea.
- reptiles replaced amphibians in abundance, but is also the age of amphibians
- ended with the greatest extinction event

Answer 23

permian period

Question 24

colloquially as the Great Dying, formed the boundary between the Permian and Triassic geologic periods, and with them the Paleozoic and Mesozoic eras respectively, approximately 251.9 million years ago. It is the Earth’s most severe known extinction event,with the extinction of 57% of biological families, 83% of genera, 81% of marine species and 70% of terrestrial vertebrate species. It was the largest known mass extinction of insects. (due to volcanic activity and high levels of CO2 - climate change)
- about 90% of species were wiped out

Answer 24

permian-triassic extinction event

Question 25

second of Earth’s three major geologic eras of Phanerozoic time. Its name is derived from the Greek term for “middle life.” 252.2 million years and ended 66 million years ago

• The ancestors of major plant and animal groups that exist today first appeared during the Mesozoic, but this era is best known as the time of the reptiles and dinosaurs.
• each period has a difference of millions of years, hence, living things from each mostly did not coexist
• pangaea split into laurasia and gondwana land. consequently, animals from these continents during this era evolved differently

Answer 25

mesozoic era

Question 26

periods under mesozoic era

Answer 26

triassic, jurassic, crutaceous

Question 27

period under mesozoic era

(252-201 million years ago) began after Earth’s worst-ever extinction event devastated life.
- pangaea cracks
- first mammals (rodents, etc) – shrew like animals derived from reptiles
- small dinosaurs (first reptiles)
- reptiles are dominant
- ended with an extinction event

Answer 27

triassic period

Question 28

this extinction event marks the boundary between the Triassic and Jurassic periods, 201.4 million years ago

• cause unknown by CO2 daw sa google

Answer 28

triassic-jurassic extinction event

Question 29

period under mesozoic era

second of three periods of the Mesozoic Era. Extending from 201.3 million to 145 million years ago, it immediately followed the Triassic Period
- dinosaurs learned to travel - first birds appear
- dinosaurs are dominant
- pangaea splits into laurasia and gondwana land

Answer 29

jurassic period

Question 30

period under mesozoic era

the period between 145.5 and 65.5 million years ago,* the last period of the Mesozoic Era, following the Jurassic and ending with the extinction of the dinosaurs (except birds).
- flowering plants appeared
- t-rex is only superior in certain continents
- longest period of mesozoic
- dinosaurs from jurassic park

Answer 30

crutaceous period

Question 31

a global extinction event responsible for eliminating approximately 80 percent of all species of animals at or very close to the boundary between the Cretaceous and Paleogene periods, about 66 million years ago.
- a bolide (meteorite or comet) impact may have triggered the extinction event by ejecting a huge quantity of rock debris into the atmosphere, enshrouding Earth in darkness for several months or longer. With no sunlight able to penetrate this global dust cloud, photosynthesis ceased, resulting in the death of green plants and the disruption of the food chain. (asteriod-nasunod parts ng earth - smoke - block sunlight - affected plants - herbivores - carnivores)

Answer 31

K-T extinction event (Crutaceous-Tertiary, Kreide is german for crutaceous which means chalk)

Question 32

third of the major eras of Earth’s history, beginning about 66 million years ago and extending to the present. It was the interval of time during which the continents assumed their modern configuration and geographic positions and during which Earth’s flora and fauna evolved toward those of the present.
- birds and mammals survived

Answer 32

cenozoic era

Question 33

periods under cenozoic era

Answer 33

paleogene, neogene (tertiary)
quaternary

Question 34

period under cenozoic

the first of three periods in the Cenozoic Era. The Paleogene represents less than 1% of geologic time; however, the rocks of this period were deposited quite recently and are, therefore, at or near Earth’s surface.
- first large mammals, mammals are dominant

Answer 34

paleogene

Question 35

period under cenozoic

the replacement of vast areas of forest by grasslands and savannahs. New food sources and niches on the grasslands and savannahs fostered further evolution of mammals and birds. Whales diversified in the seas, and sharks reached their largest size during the Miocene.
- grass becomes widespread
- hominids (human ancestors) appeared

Answer 35

neogene period

Question 36

is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy. It follows the Neogene Period and spans from 2.58 million years ago to the present.

• ice age starts at pleistocene epoch and ends at holocene
• first humans appear, when humans became dominant

Answer 36

quaternary period

Question 36

is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy. It follows the Neogene Period and spans from 2.58 million years ago to the present.

• ice age starts at pleistocene epoch and ends at holocene
• first humans appear, when humans became dominant

Answer 36

quaternary period

Question 37

big 5 extinction events in phanerozoic eon

Answer 37

ordovician-silurian extinction event
late devonian extinction event
permian-triassic extinction event
triassic-jurassic extinction event
K-T extinction event

Question 38

what is usually the cause of mass extinctions throughout the history

Answer 38

climate change and atmospheric conditions, usually dominant species get extinct

Question 39

any animal or plant preserved in the rock record of the
Earth that is characteristic of a particular span of geologic time or environment
▪ the basis for defining boundaries in the geologic time
scale and for the correlation of strata

Answer 39

index fossils

Question 40

index fossils must be

Answer 40

• distinctive or easily recognizable
• abundant
• have a wide geographic distribution and a short range through time

(should be found in several continents but only single layer)

Question 41

type of fossils

Answer 41

true form, molds, casts, trace fossils, microfossils

Question 42

type of fossil
real body parts of living things that were either frozen or replaced by mineral (petrified); example frozen mammoth, insects in amber (tree sap that solidified and crystallized, petrified bones
- as it is

Answer 42

true form

Question 43

type of fossils

• imprint of body parts on rocks
• shell bodied - natrap sa bato - imprint

Answer 43

molds

Question 44

type of fossil

• petrified replica of a body part
• empty shell - filled with sediments - shape retained

Answer 44

casts

Question 45

type of fossil
- footprints, claw marks, tooth marks, nests, fossilized feces
- no body parts

Answer 45

trace fossils

Question 46

type of fossil

• tiny remains of bacteria, protists, fungi, animals, and plants found/trapped in rocks and sediments

Answer 46

microfossils