Geological Time Scale and Mass Extinctions

Geologic Time Scale

​Eon, Era, Period, Epoch

• ​The Geographic time scale HAS to be organized, therefore we organize it by dividing them into fractions of time (Some are larger then others).

Multiple Choice

What is the largest unit of time on the geologic time scale

• Era

• Eon

• Epoch

• Period

Multiple Choice

What Eon, Era, Period and Epoch are you living in today?

• Phanerozoic, Cenozoic, Quaternary, Holocene

• Triassic, Jurassic, and Cretaceous

• The Cambrian period

Multiple Choice

What are the fractions of time in order from LEAST to GREATEST?

• Epoch, Eon, Era, Period

• Eon, Era, Period, Epoch

• Period, Epoch, Eon, Era

• Epoch, Period, Era, Eon

​Uniformitarianism

• Earth is about 4.6 Billion years old

​

• ​The principle of uniformitarianism states that geologic events (Like mountain building or erosion) that happened in the past can be explained by current geologic events.

• Summarized: Its the idea that Earth's features are always changing and the present is an indication to what happened in the past.

​Gradualism

• ​Gradualism shows that fossils change very slowly over time.

  ​

• Many fossils show that many present day organisms possess similar features to their past ancestors.

​

• ​Brontosaurus

​Giraffe

​Catastrophism

• ​the theory that changes in the earth's crust during geological history have resulted chiefly from sudden violent and unusual events.

​

Examples:

• ​Meteor Impacts (Dinosaur Extinction)

• Ice Age​

• Hurricanes, Tornados, ​Blizzards, Droughts

• MASS EXTINCTION​

Multiple Choice

The geologic time scale is a record of....

• the history of fossils only

• the history of rocks

• the history of rock layers and fossils

• geologist notes

Multiple Choice

Paleontologists infer that the earth is approximately how many years old?

• 4.5 million years

• 450 billion years

• 4.5 billion years

• 450 million years

Multiple Choice

Which Rock Layer is the oldest?

• A

• B

• C

• D

Multiple Choice

Which Rock layer is the youngest?

• A

• B

• C

• D

Multiple Choice

What Period are we currently in?

• Triassic

• Cenozoic

• Quaternary

• Jurassic

Multiple Choice

What does this picture represent

• Uniformitarianism

• Gradualism

• Catastrophism

Multiple Choice

What does this picture represent?

• Gradualism

• Catastrophism

• Uniformitarianism

Multiple Choice

What does this represent

• Catastrophism

• Gradualism

• Uniformitarianism

Multiple Choice

Paleozoic, Mesozoic & Cenozoic are all ________.

• Epochs

• Eras

• Periods

• Eons

Multiple Choice

Describe how geologists separate time periods.

• By special events that have happened in that period.

• By looking at the Relative Time of a Fossil

• By counting the years a fossil has been preserved

• By the animals in the time period.

Precambrian Era

• Earth's first era of time

• Began 4.6 mya: Creation of Earth

• Began with simple life forms such as bacteria and simple algae

• A rise of simple organisms such as jellyfish and sea worms by the end of the era

• Few fossils from era

Precambrian Era

• Earth's first era of time

• Began 4.6 mya: Creation of Earth

• Began with simple life forms such as bacteria and simple algae

• A rise of simple organisms such as jellyfish and sea worms by the end of the era

• Few fossils from era

Multiple Choice

How old do Paleontologists believe the Earth is?

• 2021 years old

• 4.6 million years old

• 4.6 billion years old

• 3.6 billion years old

Paleozoic Era

• Began with the early invertebrates (trilobites and brachiopods) --> early vertebrate fish --> arachnids and insects ---> first amphibians --> reptiles became dominant near end

• Early land plants included simple mosses, ferns, and then cone-bearing plants

• By the end of the era, seed plants were common

Era Mass Extinction

• The mass extinction that ended the era caused most marine invertebrates as well as amphibians to disappear

Mesozoic Era

• Reptiles were the dominant animals of this era, including dinosaurs

• Small mammals and birds appeared

• Toward the end of the era, flowering plants appeared and the kinds of mammals increased

Era Mass Extinction

• The mass extinction that ended the era caused the dinosaurs to become extinct

Cenozoic Era

• New mammals appeared while others became extinct

• The diversity of life forms increased

• Flowering plants became most common

• Humans are also part of the most recent period of this era

Multiple Choice

Name the 4 time frames in order from oldest to youngest.

• Precambrian Time, Paleozoic Era, Mesozoic Era, Cenozoic Era

• Mesozoic Era, Precambrian time, Cenozoic Era, Paleozoic Era

• Paleozoic Era, Mesozoic Era, Precambrian Time, Cenozoic

Open Ended

What era are we living in now?

Multiple Choice

The time span that lasted the longest was the...

• Precambrian

• Mesozoic

• Paleozoic

• Cenozoic

​GEOLOGIC TIME SCALE

Multiple Choice

Which is the longest unit in the Gelogic time scale?

• Eon

• Era

• Period

• Epoch

Multiple Choice

Which is the shortest unit in the Gelogic time scale?

• Eon

• Era

• Period

• Epoch