Chapter 5: Fossils and Geologic Time

Topic 4: The Geologic Time Scale

Geologic Time videos

• animated song

• Mr.Parr song

• Mr.Parr music video

• Earth history in a year's time

Item #1

Based on the radiometric dating of rocks on Earth and from space (moon rocks, meteorites) the Earth is estimated to be ____________________________ years old. This span of time is known as _________________________ time

4.6 billion

geologic

Item #2

All of earth’s geologic time is divided into distinct intervals based on major events (changes) on Earth. These divisions are described by the _________ ______________ Geologic time scale

Item #3

. The largest divisions of time are called ________________. We presently live in the ______________________ eon, which began about __________________________ years ago. This time span is marked by an abundant supply of different species of life on Earth. This eon is divided into three _____________ based on major changes to the profile of life on Earth.

eonsphanerozoic

550 million

eras

Item #4

The boundaries between eras are marked by major amounts of _____________________ to species. This represents the death of every member of a species. Many of these events are linked to global ___________________ change or catastrophic events such as a meteor impact.

extinction

climate

Item #5

The ______________________ era is known as the age of the “fish” (ancient marine life). It ended with a mass extinction that killed nearly __________ % of all species around at the time. Toward the end of this era, ____________________, ______________________, and ___________________ began to appear. The Appalachian mountains formed in North America during this era.

paleozoic

90

reptiles

amphibiansinsects

Note: All major land plants (non-flowering) evolved during this era.

All time prior to paleozoic referred to as “pre-cambrian” era)

Typical paleozoic life

Item #6

The ___________________________ era is known as the age of the reptiles (including dinosaurs). Small mammals and __________________ appeared toward the end of this era. The Rocky Mountains formed in North America during this time. This era ended with a mass extinction that killed about ____________ % of all species around at the time.

mesozoic

birds

15-20

NOTE: Flowering plants and bees appeared late in this era.

Item #7

The ____________________________ era is the most recent and the one we live in today. It is known as the age of the _______________________ and includes the last ice age and the formation of the Himalaya Mountains.

cenozoic

mammals