Geologic Time

1

Add this

unit to

your Table

of

contents!

A timeline of your education

• If we made a timeline of your education, where would you fall??

• What would we use as the scale?

• Grade levelK 1 2 3 4 5 6 7 8 9 10 11 12K 12

Where would you fall on the timeline of the Earth’s history??

4.6 billion years ago Present day

Fossils and Geologic Time

The geologic time scale organizes geologic and evolutionary events.

It is based on evidence in the fossil record and has been shaped by mass extinctions.

How do extinctions shape Geologic Time?Mass extinction- A large number of species become extinct

After a mass extinction, opportunities open for new life-forms to emerge.

Geologic Time Scale

Divisions of the Geologic Time Scale

Precambrian Era

Paleozoic Era

Mesozoic Era

Cenozoic Era

The Precambrian Era 4.6 billion years ago – 542 million years ago ~88% of the earth’s history

Major Events

Formation of the Earth’s crust from molten rock

First appearance of life ---bacteria!

First organisms could photosynthesize----

Oxygenated atmosphere First multi-cellular organisms

Major Events

MASS Extinction- widespread glaciation Geologists compared the Earth to a giant snowball during this time

DOMINATE ORGANISMS Bacteria Multicellular organisms

Fossils found in South Australia

Cyanobacteria and stromatolites

Pictures of Precambrian Era Life and Fossils

The Paleozoic Era

542 million years ago - 251 million years ago

Major Events

Cambrian explosion (of life)! Primitive fishes appear Mass EXTINCTION

Major Events

Plants colonize land Insects and amphibians appear ANOTHER Mass EXTINCTION

Major Events

Seed plants dominate land

Reptiles become dominate

DOMINATE ORGANISMS

Plants Fishes Insects Amphibians Reptiles

Pictures of Paleozoic life and fossils

Warm-up 10/16/13

1. What years did the Precambrian Era span?

4.6 billion years ago – 542 million years ago

2. What percentage of Earth’s history does the Precambrian Era account for?

88%17

The Mesozoic Era

251 million years ago – 65.5 million years ago

Major Events

Dinosaurs appear Mammals appear Birds appear Flowering Plants appear

Major Events

MASS EXTINCTION! - Hypothesized that the extinction occurred abruptly when a 10 km meteorite hit the Earth.

DOMINATE ORGANISMS Reptiles Dinosaurs Conifer trees Flowering Plants

Mesozoic Era pictures and fossils

The Cenozoic Era

65.5 million years ago – Present day

Major Events

Mammals diversify

(age of the mammals)

Forests dominate land

Grasslands appear

DOMINATE ORGANISMS

Wooly Mammoth Primates Mammals Early humans

Cenozoic Era pictures and fossils