Geology and Climate Quiz: Permian to Cenozoic

Geologic Time Scale

• The geologic time scale differentiates Earth's history based on life forms that existed at specific times.
• The scale is divided into eons, eras, periods, and epochs.
• Periods are basic units of geologic time, during which specific rock systems form.
• Eras group similar periods together.
• Eons are the largest divisions, grouping related eras.

Activity 2

• Students were asked to create a timeline of Earth's history.
• The timeline needed to include eons, eras, periods, and epochs.
• Students should detail significant events and life forms of each period.

Lesson Objectives

• Students will be able to describe the general features of Earth's history.
• The sequence and dates of the geologic time scale will be included in the description.
• The characteristics of major organisms from the different periods will be part of the description.

Discussion

• Introduction: This section provides background on the concept, definition, and significance of Earth's Geologic Time Scale.
• Eons: The section discusses major eons within the Earth's time scale, including Precambrian (Hadean, Archean, and Proterozoic) and Phanerozoic.
• Eras: This section details eras within the Phanerozoic eon, such as the Paleozoic, Mesozoic, and Cenozoic Eras.
• Periods: The section explains the numerous periods within the major geologic eras.

What is Geologic Time Scale?

• The geologic time scale details Earth's history based on fossils and life forms.
• Fossils are the remains of organisms from the past, preserved in rock.
• Fossils provide evidence of life at specific times in Earth's history.
• Without fossils, Earth's history before human civilization would be less understood.

What is Geologic Time Scale? (continued)

• Studying the geological time scale is required for understanding Earth's physical geology and history in detail.
• This knowledge is vital for students of Earth, atmospheric, and all life sciences.
• Understanding the timescale of Earth's formation and the evolution of life is key.

What is Geologic Time Scale? (continued 2)

• The age of Earth is related to the age of the Solar System.
• Earth's evolution is extensive, encompassing life, continents, ocean basins, and mass extinctions.
• Geological records (like surface rocks and sediments) show evidence of past life forms and environments.

Geologic Time Scale (continued 3)

• An Era is a subdivision of the geologic time scale, next to longest, based on major changes in the fossil record.
• A Period is based on existing life forms at that time.
• An Eon is the longest, largest subdivision based on abundance of certain fossils.
• An Epoch is the smallest subdivision, marked by life form differences and varying from continent to continent.

How GTS was constructed

• The Geological Time Scale utilizes evidence from various sources.
• Field observations, fossil records, and stratigraphic correlations are among the sources.
• Radioactive dating, paleomagnetic orientations, and the Earth's orbital pattern and daily rotation are also utilized for precise dating.
• Significant events like mass extinctions, species or genera appearances, mountain building, continental drift, and glaciation are taken into account.

How GTS was constructed (continued)

• Radiometric dating, paleomagnetism, and related methods allow for greater precision of the geologic time scale.

History of Earth

• Earth's history exhibits distinct and contrasting features in natural systems.
• Early and late Earth history varied significantly, necessitating a detailed timescale.
• This timeline divides Earth's history into units of millions or billions of years.

History of Earth (continued 2)

• Understanding early Earth history is described in billion-year terms.
• Understanding late Earth history is described in million-year units.
• Recent time is described in thousands and hundreds of years.
• Experts reconstructed events using Earth's physical systems.
• The geological time scale has universal application.

What is the origin of the geologic time scale?

• Miners were among the first to study geologic relationships of different rock units.
• 1600s & 1500s saw the development of interest in local relationships of rock units.
• Nicholas Steno, a 17th-century Danish physician described how the position of a rock layer could reflect relative age.
• Steno devised three key principles for interpreting geologic time (i.e., superposition, horizontality, and lateral continuity).

What is the origin of the geologic time scale? (continued 2)

• The principle of superposition identifies the oldest rock layer at the bottom.
• The principle of horizontality states original rock layers are layered horizontally.
• The principle of original lateral continuity describes layers extending laterally until interrupted.

What is the origin of the geologic time scale? (continued 3)

• James Hutton, a Scottish geologist, proposed uniformitarianism ("the present is the key to the past").
• William Smith, a British geologist, demonstrated faunal succession (fossils found in rocks in a definite order).
• The principle of biologic succession states that every age has unique fossil remains unique. This can be used to correlate rock layers horizontally and vertically.

Precambrian Eon

• This supereon encompasses 85% of Earth's history (4.6 billion to 540 million years ago).
• Hadean Eon (4.6 billion years ago): Earth's creation and solidification of the continental and oceanic crust.
• Archean Eon (4 billion years ago): Development of Earth's first life forms.
• Proterozoic Eon (2.5 billion years ago): Appearance of multi-celled animals and the formation of continents.

Precambrian Eon (detailed)

• Hadean Eon: Solar system creation, solar nebula, asteroid, comet, moon, and planet formation; hellish early environment.
• Archean Eon: 70% of continental landmasses had formed; small "island"-like landmasses existed; Earth acquired reducing atmosphere (methane, ammonia). Water (from comets, minerals) condensed, creating oceans; microbes (chemoautotrophs) lived on ocean floors;
• Proterozoic Eon: Continents formed; available shield rock collided; first supercontinent, Rodinia; coastal waters were populated by stromatolites (photosynthetic algae).

Precambrian Eon (detailed 2)

• Ediacaran Period (the last part of the Proterozoic Era): First multicellular organisms appeared in this period, including soft-bodied heterotrophs and autotrophs.
• Cnidarians (sea anemones, corals) developed and had sac-like bodily systems. Sponges lack organs; they filter food. Annelids (segmented flatworms) have fluid-filled bodies; respiration through skin.

### Phanerozoic Eon

• Cenozoic Era (65 million years ago - present): Most recent era; age of mammals, humans evolved.
• Mesozoic Era (245 million years ago): Dinosaurs, mammals, and certain birds evolved. Also included a mass extinction that wiped out many dinosaurs.
• Paleozoic Era (544 million years ago): Diversity of marine life exploded; the Cambrian explosion (first invertebrates, fish, amphibians, insects, reptiles, and plants), followed by the Permian extinction (major extinction event).

Paleozoic Era (detailed)

• The Cambrian Period (544 million years ago): A period of multicellular life explosion, known as the Cambrian explosion.
• Marine life thrived (trilobites, invertebrates), the first vertebrates (fish), amphibian and insects subsequently emerged.
• Plants developed on land; coal swamps formed.
• Reptiles developed.
• Mass extinction (permian extinction) ended this era.

Paleozoic Era (detailed 2)

• Ordovician Period: Marked by marine invertebrates (trilobites).
• Silurian Period: Development of jawed fishes (Ostracoderms were among the first).
• Devonian Period: Ferns and trees evolved on land, leading to vertebrate colonization of the land. Tetrapods developed.
• Carboniferous Period: Tetrapods lay eggs on land; amphibians evolved; trilobite were fading away; first conifers and dragonflies arose.
• Permian Period: Mega mammals; cockroaches' ancestors; reptiles, sharks, bony fishes, amphibians, and others evolved; this era ended with the Permian extinction, a major mass extinction event.

Mesozoic Era (detailed)

• The Triassic period: Giant reptiles, dinosaurs emerged.
• The Jurassic period: Birds, mammals rose.
• The Cretaceous period: Iconic dinosaurs (like Triceratops and Pteranodon); coniferous plants existed; flowering plants emerged; large dinosaurs continued to grow; Cretaceous–Paleogene extinction event marks the end of the era with massive disruption in the food chain and extinction of non-avian dinosaurs.

Cenozoic Era (detailed)

• Paleogene period (65-23 mya): Mammals were diversifying; mammals. horses, pigs, dogs, and cats developed in this period. Also developed were large flightless birds (like the Diatryma).
• Neogene period (23-2.6 mya): Early primate. evolution; cattle, sheep, goats, antelope, and gazelles also developed.
• Quaternary period (2.6 mya -present): Ice ages; modern humans; woolly rhinoceroses and mammoths developed.

Holocene Epoch

• This period: Current geologic period (12,000-11,500 years ago - present).
• Characterized by a warming trend; glacial retreat; tundra transitioned to forests.
• The last ice age ended; huge mammals died; humans adapted their diets toward smaller game and plants.
• Agriculture and domestication began around 8000 BC; human population growth increased significantly.
• Industrial Revolution caused population explosion.

Mass Extinctions

• There are five major mass extinctions in Earth's history, termed the Big Five
• Each was characterized by extremely high extinction rates over a short period of time(typically under 2 million years).
• Big Five extinctions: End Ordovician, Late Devonian, End Permian, End Triassic, and End Cretaceous.
• Causes vary, but always involve significant changes in climate and environments. The causes include glacial periods, volcanic activity, intense heating, and asteroid impacts.

Causes of Permian Extinction

• Temperature crises, alteration of the carbon cycle, and population explosion of methane-producing microbes are potential causes.
• The assembly of Pangea could have played a role as well.

Paleozoic Geology and Climate

• Continents shifted during the Paleozoic era, against a changing climate.
• Rodinia (a supercontinent) joined together before fragmenting into Gondwana (Southern Hemisphere) and smaller continents.
• The climate changed from warm periods to ice ages.

Paleozoic Geology and Climate (continued 2)

• During the Cambrian, the earth was warm; followed by an Ordovician ice age.
• Gondwana moved south; smaller continents moved closer together.
• The Silurian period saw rising sea levels, which formed shallow inland seas; landmasses moved closer together to form Euramerica.
• Pangaea (a supercontinent) emerged as the end of the Paleozoic era neared.

Test your knowledge of geological periods and climate changes from the Permian through the Cenozoic Era. This quiz covers major events, extinctions, and the characteristics of different geological periods. Ideal for students of earth sciences and geology.