geologic time scale

rock correlation and fossil correlation

geologist examine in detail the ____ in ancient rock layers, which allow them to relate the events in the rocks to earth's history.

geologic time scale

breaks relative geologic time into various divisions of known relative age

geologic time scale

divided into series of time intervals that are unequal in length and not like the time intervals in a clock

time intervals

are divided based on the significant events in the history of earth, some of which include the mass extinction of a large percentage of the Earth's flora and fauna that happened between the permian and triassic periods, and the first appearance of animals with hard parts between the precambrian time and the paleozoic era

eons, eras, periods, and epochs

the wide scope of geologic time in the history of the earth is separated into?

eons

are the largest intervals of geologic time with duration of hundreds of millions of years

hadean eon, archeozoic eon, proterozoic eon, phanerozoic eon

four eons of the geologic time scale

eras

are subdivided into period

epochs

are the smaller subdivisions of the cenozoic era

holocene epoch, quaternary period, cenozoic era of the phanerozoic eon

we now live in the?

precambrian

is an informal name given to the first three eons of the geologic time scale which include the hadean, archean, proterozoic eons

phanerozoic eon

4.5 billion years ago

cambrian period

542 million years ago

precambrian period

spans 4 billion years, or about 88 percent of the total lifespan of earth

precambrian period

the major events that took place during the ____ include the moon's formation, the filling of ocean basins, the first evidence of life, the beginning of plate tectonics, and formation of the continents, and the oxygenation of the atmosphere

hadean eon

4.5 - 4 bya

hadean eon

is known as the rockless eon

hadean eon

except for the meteorites, no existing rocks on earth today are from the __

hadean eon

during this time, the earth was molten, and it would only solidify as it cooled

hadean eon

this happened about 800 million years into the earth's history

hadean eon

the earth's continental and oceanic crusts began to solidify, marking the beginning of earth's geological history, which likely happened prior to 3.8 billion years

archean eon

1.5 billion years ago

archean eon

preceded the proterozoic eon

eoarchean era, paleoarchean era, mesoarchean era, neoarchean era

four eras of
archean eon

archean eon

it was during the ___ that single-celled organisms, such as blue green algae, archeans, and bacteria, first appeared

archean eon

it is the beginning of free oxygen in the atmosphere

proterozoic eon

began 2.5 million years ago and ended 542 million years ago

paleoproterozoic, mesoproterozoic, neoproterozoic

following eras of
proterozoic eon

proterozoic eon

during this eon, the first continents appeared

proterozoic eon

this was also the time when continents merged into a single land mass called Rodinia

proterozoic eon

scientist also found many fossils of bacteria and archaea, as well as eukaryotic cells, from this time during the mesoproterozoic era, which enabled eukaryotic organisms to proliferate

proterozoic eon

is marked by the appearance of multicellular animals like sponges and the mass extinction of these organisms

phanerozoic eon

precedes the precambrian eon

phanerozoic eon

it began 542 million years ago

paleozoic era, mesozoic era, cenozoic era

era of phanerozoic eon

phanerozoic eon

the first life forms with parts, such as shells, scales, and bones, and teeth, appeared during this eon

phanerozoic eon

the fossils of these life forms are great tools in the study of the history of phanerozoic eon

paleozoic era

the supercontinent pangaea was formed during this era

paleozoic era

through a series of collisions, north america, europe, and siberia were gradually joined forming the continent, laurasia

paleozoic era

continent gondwana was also formed, which included south america, africa, australia, antartica, india, and parts of china, was situated near the south pole

paleozoic era

gondwana collided with laurasia during the end of this era resulting in the formation of supercontinent, pangaea

cambrian period

the paleozoic era is also the beginning of the ___ during which shallow seas covered parts of the continents and a mild climate existed

cambrian period

known as the age of trilobites, the cambrian explosion of life occured, and all existing phyla developed

cambrian period

many marine invertebrates like shellfish, echinoderms, trilobites, brachiopods, mollusks and delicate coelenterates evolved

cambrian period

during this period, the supercontinent rodinia began to break into smaller continents

cambrian period

the mass extinction of trilobites and nautiloids happened at the end of the cambrian period which may have been caused by glaciation

ordovician period

many volcanoes and mountains formed during the ordovician period

ordovician period

north america was flooded

ordovician period

primitive plants appeared on land

ordovician period

the first corals, primitive fishes, seaweed and fungi also appeared

ordovician period

graptolites, bryozoans, gastropods, bivalves, and echinoids were also dominant

ordovician period

it was also the first time that global cooling and glaciation, and frequent volcanic activities were observed

ordovician period

the period ended in huge extinction due to glaciation

silurian period

during this period, the caledonian mountains of scandinavia rose, and coral reefs were formed

silurian period

the first jawed fishes and arthropods like insects, centipedes, and millipedes appeared

silurian period

the first vascular plants with water conducting tissue appeared on land such as cooksonia, a primitive terrestrial plant

silurian period

brachiopods, crinoids, and corals were also abundant

silurian period

a rise in sea level occured world wide

devonian period

the acadian mountains of new york rose during this period, and the erosion of mountain resulted in the deposition of much sediments in seas

devonian period

known as the age of fishes, fishes and terrestrial plants became abundant and divere

devonian period

the first tetrapods, amphibians, sharks, bony fish, and ammonoids appeared during the latter part

devonian period

many coral reefs, brachiopods, and crinoids existed

devonian period

new insects like springtails appeared

devonian period

a mass extinction event occured near the end of the devonian period which as probably due to glaciation or meteorite impact

mississippian period

the appalachian mountain of north america were formed during this period

mississippian period

ice covered large areas of the earth, and swamps covered the lowlands

mississippian period

the first winged insects appeared

pennsylvanian period

First reptiles and cockroaches. Major coal forests.

permian period

the ural mountains of russia rose at this time

permian period

known as the age of amphibians, amphibians and reptiles dominated this period

permian period

gymnosperms were the dominant plants

permian period

the continents merged into a single super-continent, pangaea

permian period

phytoplankton and plants supplied oxygen to the earth's atmosphere which was close to the present level

permian period

the first stoneflies, true bugs, beetles, and caddisflies appeared

permian period

ended with the largest mass extinction

permian period

trilobites went extinct, together with all animal families, almost all marine species, many trees perhaps caused by glaciation or volcanism

mesozoic era

spans about 186 million years

triassic, jurassic, cretaceous

three periods of the mesozoic era

mesozoic era

the breakup of the supercontinent pangaea also ocurred during this era

mesozoic era

about 165 million years ago, a rift developed between what is now North America and Western Africa, resulting in the formation of atlantic ocean

mesozoic era

means middle animals

mesozoic era

during this era, dinosaurs lived

mesozoic era

it was not until the jurassic period that the dinosaurs became very diverse

mesozoic era

except for birds, dinosaurs became extinct at the end of the cretaceous period

mesozoic era

terrestrial vegetation also greatly changed

mesozoic era

ferns, cycads, ginkgophytes, bennettitaleans, and other unusual plants lived in the early part of this era

mesozoic era

modern gymnosperms, such as conifers, first appeared in their current earliest angiosperms had appeared and began to diversify, largely taking over from other plant groups

triassic period

the palisades of new jersey and the caucasus mountains of russia were formed during this period

triassic period

the first dinosaurs, mammals, and crocodyliformes appeared

triassic period

mollusks were the dominant invertebrate

triassic period

many reptiles like turtles and ichthyosaurs came to existence

triassic period

the true flies also appeared

triassic period

ended with extinction events, called the end-triassic extinction event, which may have been cause by volcanic eruptions that led to global warming and ocean acidification

triassic period

this resulted in the decimation of about 76 percent of marine and terrestrial life, thus paving the way for the beginning of the Jurassic period and the 135-million-year dominance of the dinosaurs

jurassic period

the rocky mountains rose during this period and the volcanoes of western north america were active

jurassic period

many dinosaurs, including the giant lizard-hipped during dinosaurs roamed the earth.

jurassic period

many ferns, cycads, ginkoes, rushes, conifers, mollusks, and flying reptiles appeared

jurassic period

the first birds, such as the archeopteryx appeared

jurassic period

the first flowering plants also evolved at this time

jurassic period

there were minor extinctions that occurred during 190-160 million years ago