Geological Time Scale Flashcards
(117 cards)
1
Q
How old is the earth?
A
Approximately 4.6 billion years old (approx. 1/3 age of the universe)
2
Q
Clues to earth’s past
A
Rocks of crust
3
Q
The theory that changes in the earth’s crust during geological history have resulted from the action of continuous and uniform processes.
A
Uniformitarianism
4
Q
Father of modern geology
A
James Hutton
5
Q
Determining chronology of events in the history of earth using evidences such as evolution in sedimentary rocks accumulated to layers thru time
A
Geologic dating
6
Q
Determine the exact age of an artifact or site (quantitative), works better for igneous and metamorphic rocks,
A
Absolute dating
7
Q
Methods: Biostratigraphy, stratigraphy, and cross dating thermoluminescence
A
Absolute dating
8
Q
Determines which object is older, Works better for sedimentary rocks, Know order of events but not date
A
Relative Dating
9
Q
This method of relative dating works better with sedimentary rocks
A
Stratigraphy
10
Q
Rock layers form in a horizontal position
A
Original horizontality
11
Q
Made fundamental contributions to 4 branches of science, founder of the study of fossils and one of the main founders of geology
A
Nicholas Steno
11
Q
Rock layers in the bottom are older than those on top of them
A
Superposition
12
Q
Rock layers are extended laterally and continuously Similar layers of rock or sediment that are separated by a valley or other erosional feature were once continuous.
A
Lateral continuity
13
Q
Rock layers
that are cut across are older than the cut
itself
A
Cross-cutting relations
14
Q
Any inclusion in rock layers are older than the rock that contains it
A
Inclusion
15
Q
Remains of Ancient Plants and Animals, Evidence of Life. A preserved remnant, remains, or impression of a prehistoric organism. At least 10000 years. Important in studying the history of the
earth
A
Fossil
16
Q
Commonly preserved fossils (hard parts of organisms)
A
Bones, shells, hard parts of insects, woody material
17
Q
Rarely preserved (easily decayed parts of organisms)
A
Internal organs, skin, hair, feathers
18
Q
Kind of fossil that can be seen through a microscope such as bacteria and pollen
A
Micro fossil
19
Q
Kind of fossils that are large, hard part of tree or dinosaur bone
A
Macro fossil
20
Q
Formed when materials replace the structure of the organism
A
Petrification
21
Q
Formed due to burial of plants or plant parts in sediments, formed by imprint
A
Compression
22
Q
Preservation of original skeletons and soft body parts. (like an amber resin)
A
Preserved remains
23
Q
Fossils of the actual animal or actual part, formed when the tissues of animals didn’t decay over the years
A
True fossil
24
Where are true fossils commonly found?
Ice, tar, natural asphalt
25
Hollow impressions of living things in a
rock, mud or clay, negative image of an organism (imprint), Formed when an animal, planet, or other
organism dies and is covered by sediment, its flesh decays and bones deteriorate due to chemical fractions, and a cavity remains below the ground surface
Mold fossil
26
Created when minerals and sediments enter a cavity or mold (sometimes from a mold fossil) and hardens, creating a cast
Cast Fossil
27
Impressions of rocks that showed
various activities, Commonly, fossils of footprints, burrow,
trail, and or other trace of the animals (but not the animal itself)
Trace fossil (ichnofossil)
28
Where do fossils occur
Sedimentary rocks
29
True or false: Heat of Melting or Metamorphism Would Destroy Almost Every Type of Fossil
True
30
To be preserved, organisms have to be:
Buried rapidly after death, preserved from decay
31
Newest epoch
Anthropocene - July 2023
32
What is an epoch?
It is a long period of time that is characterized by great change
33
How are epochs discovered?
Through golden spikes. Climatic, magnetic, biologic, isotopic
34
What is the golden spike of the anthropocene?
Radioactive plutonium from nuclear weapons testing in the 1950s
Marie Curie discovered radioactive elements and she died because of it
Japan had tsunamis and released radioactive waste
Radioactive plutonium from nuclear weapons testing in the 1950s has widespread global impacts that are recorded in rock
35
What do other golden spikes tell us about earth? End of the ice age...
shifting values of excess deuterium reflect a time when earth entered a warmer climate.
36
A scale organized according to when certain programs lives on earth
Geological time scale
37
Longest subdivision which can last up to hundreds of millions of years.
Determined by the prevalence of certain fossils
Eon
38
An ___ marks a major shift in the types
of fossils present.
Era
39
_____ are divisions within an era. They mark stages within an era where different kinds of life existed.
Periods
40
Shortest subdivision. It divides periods into smaller
units
Epoch
41
What are the four major divisions of the geologic time scale?
Precambrian era, Paleozoic era, Mesozoic era, Cenozoic era
42
Represents the first 88% of Earth’s history (mostly devoid of fossils).
Precambrian era
43
Represents ~ 8.5% of
Earth’s history (invertebrates, fishes, amphibians, vertebrates and land plants first appear).
Paleozoic era
44
Rep. ~ 3.5% of Earth’s
history (dinosaurs,
5 earliest birds, and
mammals).
Mesozoic era
45
Rep. ~ 1.4% of Earth’s history (humanoids show up late ~0.04% of history
Cenozoic era
46
This era lacks fossils because there were no large organisms that inhabited the earth
Precambrian era
47
Precambrian era had a single-celled microorganisms called
Cyanobacteria
48
True or false: Scientists have a hard time getting information from the Precambrian rocks
True
48
What was the atmosphere like during the Precambrian era?
Originally made up of gasses similar to those released in volcanic eruptions; water vapor, CO2, N, no oxygen
49
Used photosynthesis and released oxygen
Cyanobacteria
50
What is the most common precambrian fossil?
Stromatolites
Distinctively layered mounds or
columns of calcium carbonate
Not actual remains of organisms nut materials deposited by algae
Formed by the growth of blue-green algae and cyanobacteria
51
Heat flow was nearly 3 times as it is today from planetary accretion
Sculpting of earth 4.6 billion years ago
Unseen era
Earth’s surface bombarded by
meteorites (late heavy bombardment - stage)
Hot mantle caused severe volcanism - Ocean and atmosphere were formed;
core and crust were stabilized
Heavy material – core; lighter materials
– mantle and crust
Formation of moon
Dark age
Hadean eon - 4.6 to 4.0 billion years ago
52
What happened during the Hadean eon?
Earth coalesced, primordial water, earth meets moon, core accretion, magnetic field forms, asteroids and comets pelted earth
52
Were there fossils in the hadean eon
No fossil records cause temp is too high
53
Hadean eon: from a cloud of dust, gravity molded our solar system. The terrestrial planets were positioned closer to the sun.
Earth coalesced
54
Comes from comets and asteroids that collided during its early formation.
Primordial water
55
Scientists have proposed many ideas for how the Moon formed. A leading contender, the ____, speculates that when Earth was a young planet and just beginning to form, it was hit by another emerging planet named Theia, located nearby.
Giant Impact Hypothesis
56
Helps stabilize the earth's movement
Moon - Earth and moon pull each other that's why they are stable
57
Solar winds swept in hydrogen and helium closer to the sun because they were smaller in size. But the sun couldn't pull in the heavier elements. They spoiled and gelled on their own
Core accretion
Heavy metals of the earth sink
Ex: iron sinks because its too
heavy
58
Earth formed a
solid iron core. Inside weather it was multi-family layered. Surrounding the inner core earth established an outer liquid core
Magnetic field forms
59
Earth was still in the late heavy bombardment stage. This is why scientist suggests that comets may have transporter water frying later bombarded stage
Asteroids and comets pelted earth
59
This stage explains that the pull of the earth was stronger and so asteroids and comets pelted earth
Stabilizing stage
60
Formation of iron
Earth’s temperature began to stabilize
Ancient earth cooling and primitive life
4 – 2.5 billion years ago
Earth was warm and the atmosphere contained mostly methane (very little to no oxygen)
Most of earth was covered with ocean
Continents formation began
Vaalbara first supercontinent - Stabilized climate, seasons, & earth
motion due to moon’s orbit
Great oxygenation event
Iron abundant element
Archean Eon
61
What happened during the Archean eon?
Earth has its first ocean, Formation of dna-based genes, Tectonic activity builds continents, The first continent, Prokaryotic bacteria, Iron collects on the seafloor, Great oxygenation event
62
Earth began cooling, water finally could condense to form its first oceans. It's cooler so condensation can happen.
Earth has its first ocean
63
Protocells from rna-based genes around 4000 ma, after which true cells evolve along with proteins and dna. From RNA. Protein starts life
Formation of DNA-based genes
64
Only life forms that existed in the Archean Eon were
Prokaryotic bacteria - single celled, no nucleus, has genetic particles
64
Built continents, which means tectonic activity was formed
- Pangea
Tectonic activity builds continents
64
Iron collects on the seafloor
oxygen filled the oceans, it mixed with iron. Iron rusts when it reacts with oxygen, so overtime the seafloor collected rusted iron.
65
Oxygen entered the atmosphere because there was no more iron to rust in the ocean
Great oxygenation event
66
Snowball earth
Ozone layer
Multicellular and eukaryotes evolved
Earliest eukaryotic life
Oxygenated atmosphere
2500 – 542 million years ago
Lasted 1.9 billion years (longest period;
almost half of earth’s age)
Atmosphere became oxygenated
Methane and oxygen combined in the atmosphere to form carbon dioxide
Snowball earth – ice age 300 million years
Eukaryotic, aerobic life began and diversified (multicellularity) slowly
Motion of continental drift
Ozone layer began to form
Protezoic Eon
66
What happened during the protezoic era?
Oxygen crisis, first eukaryotes, snowball earth, the emergence of eukaryotes, presence of ozone layer
66
Oxygen level was too high during the ____ era
Protezoic era
67
What was the (hypothetical) first eukaryote?
Francevillian biota
68
Snowball earth
Earth froze for 300 million years
Ice age
68
How did the emergence of eukaryotes happen?
The multicellular began when an organism ate another. Multiple cells benefited due to this. Multicellular life began.
69
How was ozone layer formed
Oxygen atoms could bond and form ozone. Important in stabilizing the temp of the earth.
70
Collective term for the remaining 3 eras after: Paleozoic, mesozoic, Cenozoic
Phanerozoic eon
71
What happened during the Paleozoic era?
Cambrian explosion, the age of invertebrates, the age of fishes, age of amphibians, carboniferous rainforest collapses, permian triassic extinction
72
What was the first fossil observed?
Trilobites
72
Marked the first time on earth's timeline that we can observe fossils.
Cambrian explosion
73
Animals with endoskeleton
No back bones
After some time, they developed
themselves
The age of invertebrates
74
True or false: Fishes are jawless first before they evolved to have jaws
True
75
The first vertebrate land animal made its leap shore.
Since water is crowded
Some organisms explored to live in land
Age of amphibians
76
Amphibians took a breath of fresh air and colonized the empty continent of
Gondwana
76
Insects here became big because oxygen content was high
Carboniferous rainforest collapses
77
The great drying
Permian triassic extinction
78
Middle life
Mesozoic era
79
What era? Presence and growth of large
coniferous trees and other
related plant species
Mesozoic era
79
Why were reptiles and dinosaurs bigger during the mesozoic era?
O2 content was high, that’s why reptiles were larger then
80
Triassic, Jurassic, and cretaceous period
Mesozoic era
81
are seed-bearing plants
that do not depend on free-
standing water for fertilization; enabled them to be dominant plants
Gymnosperms
82
True or false: Reptiles in mesozoic era didn't gain an ecological advantage because they had more competition for food in dryland conditions
False: reptiles gained an ecological advantage because they had less competition for food in dryland conditions
83
Supercontinent that was separated due to plate tectonics
Pangea
83
Pangea divided into two:
Laurasia and Gondwanaland
84
______ dominated the land until the Cretaceous era.
Dinosaurs
84
What were the dominant species of plants during the Mesozoic era?
Flowering plants
84
Mammals and birds in the Mesozoic era evolved from
Reptile- like ancestors
85
Age of mammals and homo sapiens. Era that marks the existence of man.
Cenozoic era
86
_______ (flowering plants with covered seeds) replaced
gymnosperms as the dominant terrestrial plants
Angiosperms
86
What wiped out the dinosaurs
K-pg event
87
Theories on why dinosaurs died
1. History is that there was a Giant asteroid - reason for Chicxulub crater in Mexico
2. Possibly there was an
earthquake - Dinosaurs sedimented
3. From the impact, there was
force
88
What happened in the Cenozoic era
Dinosaurs went extinct, Age of mammals, Grass spreading, Apes, Stone age, Homosapiens, Cities
89
What happened in the mesozoic era?
Age of reptiles, Pangea, Age of conifers, Age of dinosaurs, Transition coming
90
______ were the only porot-humans who really began to master the use of their hands and fingers.
Hominids
91
Ancestors of humans
Hominids
92
Modern-day man, what we are known as today.
Homosapiens
93
What were the 6 major mass extinctions?
Ordovician-silurian extinction, Late devonian extinction, Permian-triassic extinction, Triassic and jurassic extinction, Cretaceous and paleogene extinction, Holocene extinction
93
Amphibian extinction
Late devonian extinction
94
Fish extinction
Ordovician-silurian extinction
95
The great dying.
96 % species wiped out
4% evolved through time
Survival of the fittest
Permian-triassic extinction
96
Extinction of lower forms of reptiles
Triassic and jurassic extinction
97
Extinction that killed dinosaurs
Cretaceous and paleogene extinction
98
_____ (Permian period) was the greatest of at least five mass extinctions to occur over the past 500 million years
The late Paleozoic extinction
99
What extinction is this?
Time of humans
Reason: habitat loss, land conversions,
poaching, climatic
Poaching: get animals from nature and
sell in the market
Climate change- lots of animals die
especially in colder regions
Holocene extinction
100
