GEOLOGIC TIME“HISTORY OF THE EARTH”

LEARNING TARGETS

2a) I can distinguish between eons, eras, periods, and epochs (DOK 1).

2b) I can identify the order of the eras and the relative length of the eras (DOK 1).

2c) I can identify key geological and biological features of the 4 different eras (DOK 1).

ESSENTIAL QUESTION

How is Earth’s history organized?

HOW OLD IS THE EARTH?About 4.6 billion years old

HOW WAS EARTH FORMED?

13.7 bya-BIG Bang Explosion of atomic particles Cooling to form clouds of H and He Star formation Galaxies Clusters

4.5 bya-Solar System Forms (Nebular Hypothesis)

Solar nebula (rotating cloud dust/gas)Planetesimals (clumps formed in spinning disk of matter)

8 Protoplanets & moonsEarly Earth impact moon

HOW IS EARTH’S HISTORY ORGANIZED?

Scientist use fossils and other clues to organize the events in Earth’s history into a timeline.

Geologic time is organized into lengths of time based on life forms present and events such as extinctions.

There are 5 mass extinctions that scientist know about throughout history.

-Cretaceous-Tertiary (KT) extinction, 65 mya- Killed the dinosaurs.

- Permian-Triassic (PT) extinction, 251 mya– Killed about 95 % of all species.

WHEN WERE THE MASS EXTINCTION EVENTS?

Mass Extinction Event

Time Frame (mya)

Types of Life Effected

Late/End Ordovician 443 mya Many species of Trilobites, Brachiopods, Graptolites, Echinoderms and Corals

Late/End Devonian 354 mya Many marine families on tropical reefs, Corals, Brachiopods, Bivalves, Sponges

Late/End Permian 248 mya 57% of all marine families, Trilobites, Eurypterids, Mollusca devastated along with Brachiopods. Many vertebrates

Late/End Triassic 206 mya Mollusca phyla, Sponges, marine vertebrates, large amphibians, many mammal-like reptiles

Late/End Cretaceous

65 mya Ammonites, Marine reptiles, dinosaurs, pterosaurs, microscopic marine plankton, Brachiopods, bivalves, and echinoderms

WHAT ARE THE DIVISIONS OF GEOLOGIC TIME?Geologic time is divided into:EonsErasPeriodsEpochs

WHAT ARE THE FOUR ERAS?

1. Precambrian Era (4600-544 mya) Longest era, bacteria-like life forms present.

WHAT ARE THE FOUR ERAS?

2. Paleozoic Era (544-248 mya) Broken down into 7 periods. 1st plants, fish, reptiles, amphibians, and insects.

WHAT ARE THE FOUR ERAS?

3. Mesozoic Era (248-65 mya) Broken down into 3 periods. Era of the dinosaurs and first mammals and birds.

WHAT ARE THE FOUR ERAS?

4. Cenozoic Era (65 mya – present) 2 periods, mammals are abundant. Homo sapiens evolve.

CHECK FOR UNDERSTANDING

Write a paragraph that covers the following:

How Earth was formed

How Earth’s history is organized

The divisions of time that is used for Earth’s history

A summary of the four eras