Semi-Finals

A system of chronological dating that relates geological strata to time

Geologic time scale

What are the 4 major divisions of the geologic time scale?

Eon, era, period, epoch

It is the largest time span of the geologic time scale

Eon

Geologic time is divided into two eons. What are these eons?

Precambrian and phanerozoic eon

This eon refers to the earliest part of the earth’s history

Precambrian eon

It is the current geologic eon in the geologic time scale

Phanerozoic eon

What are the three eons under the Precambrian eon?

Hadean, Archean, Proterozoic eons

This eon occurred 4.6 to 4 billion years ago. During this time, the solar system is forming within a cloud of dust and gas known as the solar nebula, which eventually spawned planets, etc.

Hadean eon

During this eon, the first form of life on our planet was created in the oceans

Archean eon

This eon is also called the age of the hidden life, which started 2.5 billion years ago. In this time, enough shield rock had formed to start recognizable geologic processes such as plate tectonics.

Proterozoic eon

This eon contains many definite traces of primitive life forms - the fossil remains of bacteria and blue-green algae as well as of the first oxygen dependent animals

Proterozoic eon

The time in which abundant animal and plant life has existed. It covers 541 million years to the present

Phanerozoic eon

The Phanerozoic eon is subdivided into three eras

Paleozoic era, mesozoic era, cenozoic era

This era began with the breakup of one supercontinent and the formation of another, plants became widespread

Paleozoic era

The Paleozoic era is divided into 6 periods:

• Cambrian

• Ordovician

• Silurian

• Devonian

• Carboniferous

• Permian

This period is known for ushering in an explosion of life on earth. This explosion included the evolution of arthropods and chordates

Cambrian period

This period is marked in the fossil record by an abundance of marine invertebrates. Perhaps the most famous of these invertebrates was the trilobite, an armored arthropod that scuttled around the seafloor about 270 million years before going extinct

Ordovician period

This period was the spread of jawless fish throughout the seas, mollusks and corals thrived in the oceans and land, the first undisputed evidence of terrestrial life

Silurian period

This period was the time the plants evolved though they most likely did not yet have leaves or the vascular tissue siphon up water and nutrients

Silurian period

Long before the birds evolved, the tetrapods began laying eggs on land for the first time during this period. Allowing them to break from an amphibious lifestyle

Carboniferous period

Two groups of animals that evolved during the Carboniferous period

Marine reptiles and archosaurs

This period would end with the largest mass extinction ever

Permian period

During this period, coral reefs flourished, providing shelter for fish and shelled creatures such as nautiloids and ammonoids. Modern conifers and ginkgo trees evolved on land. Terrestrial vertebrates evolved to become herbivores taking advantage of the new plant life that had colonized the land.

Permian period

This era spans from about 252 million years ago to 66 mya, was known as the age of reptiles or the age of dinosaurs because of its famous inhabitants

Mesozoic era

The current location of the continents and their modern day inhabitants including humans can be traced to this era.

Cenozoic era

This era is also known as the age of mammals because the extinction of many groups of giant mammals allowing smaller species to thrive and diversify because their predators no longer existed

Cenozoic era

Epochs under the Paleogene period

Peleocene, Eocene, Oligocene

The beginning of this period was a time for mammals that survived from the Cretaceous period. Later in this period, rodents and small horses, such as Hyracotherium are common and rhinoceroses and elephants appeared. As the period ends, dogs, cats, and pigs become commonplace

Paleogene period

This period gives rise to the early primates, including the early humans. Bovids including cattle, sheep, goats, antelope, and gazelle flourish during this period

Neogene period

Epochs under the Quaternary period

Pleistocene and Holocene

Cave-lions, sabre-toothed cats, cave bears, giant deer, wolly mammoths, and wolly rhinoceroses, were prevailing species of this period

Quaternary period