1. N: Geologic Time 1. Geologic History. a. Fossils 3
N: Geologic Time 1. Geologic History a. Fossils 3. Geologic Time Scale 4. Geologic Belts 5. NC Geologic History

2. How do we know geologic history?

3. Earth's history spans over a length of 4.5 billion years
Geologists have divided that time into units based on major geologic events and life forms

4. Past Life Forms
We discovered that some organisms only existed during certain time units, so when geologists find the remains, we know exactly which time unit a rock is from.

5. Fossils are the clues
Fossils are the preserved remains and traces of past life forms. They are found in sedimentary rocks.

6. Ordering the Grand Canyon’s History
Makes no sense without caption in book

7. Geologic Time Scale
The time scale was created to show the order of events in Earth's history of 4.5 billion years

8. Divisions
From smallest to largest, the units of geologic time are:
Epochs
Periods
Eras
Eons

9. Each unit of time is recognized by the fossils it contains! Examples: 1. Age of Coal Swamps 2.Age of Reptiles 3.Age of Mammals 4.Age of Fishes

10. M.Y.A = Million Years Ago
Each division is represented by millions of years ago (mya)

11. Geologic Belts
Rocks with similar characteristics and history are grouped together in units called - GEOLOGIC BELTS

12. North Carolina's Geologic History
In North Carolina, there are 11 different belts of igneous, sedimentary, and metamorphic rocks that have similar geologic history.

13. North Carolina's Geologic History
We know that Wilmington is in the Coastal Plain Belt and some of the rocks here formed 66 million years ago!
Let's find out more......
How and Why?

17. 12.4 The Geologic Time Scale
Structure of the Time Scale
12.4 The Geologic Time Scale
 Eons represent the greatest expanses of time. Eons are divided into eras. Each era is subdivided into periods. Finally, periods are divided into smaller units called epochs.
 There are three eras within the Phanerozoic eon: the Paleozoic, which means “ancient life,” the Mesozoic, which means “middle life,” and the Cenozoic, which means “recent life.”

18. 12.4 The Geologic Time Scale
Structure of the Time Scale
12.4 The Geologic Time Scale
 Each period within an era is characterized by somewhat less profound changes in life forms as compared with the changes that occur during an era.
 The periods of the Cenozoic era are divided into still smaller units called epochs, during which even less profound changes in life forms occur.

19. 12.4 The Geologic Time Scale
Precambrian Time
12.4 The Geologic Time Scale
 During Precambrian time, there were fewer life forms. These life forms are more difficult to identify and the rocks have been disturbed often.