1. Earth’s Cycles and Climate Change

2. 18.1 The geologic time scale
Divided into blocks of time called eons, eras and periods.

3. 18.1 Paleozoic era
Lasted from 542 to 251 mya.

4. 18.1 Mesozoic era
Lasted from 251 to 65 mya (AKA the Age of Reptiles.)

5. 18.1 Cenozoic era
Began 65 mya and is still going on (AKA the Age of Mammals).

6. 18.1 Mass extinction
Scientists have evidence that a large asteroid crashed near Mexico’s Yucatan peninsula about 65 mya.
The resulting climate change may have caused the extinction of Mesozoic Era reptiles, including most dinosaurs.

7. 18.1 Trees and absolute dating
Trees are like history books.
Each tree ring is a record of what the environment was like that year.
Wide tree rings indicated a very wet year and narrow rings indicated a dry year.

8. FYI – oldest plants
The oldest tree on record is a bristlecone pine called “Methuselah.”
It is 4,765 years old.
Gallery
Ted Talk – oldest living organisms

9. 18.2 Law of superposition
Law of superposition, which states that the bottom layer of a rock formation is older than the layer on top.

10. 18.2 Principle of Fossil succession
The organisms found in the top layers appeared after the organisms found in the layers below them.

11. 18.2 Fossils and Earth’s changing surface
Most of the land on Earth was part of a large landmass called Pangaea about 250 millions of years ago.

12. 18.3 Rocks keep moving
Rock cycle includes weathering, erosion, deposition, compaction and cementation, metamorphism, melting and crystallizing.
Plate tectonics— plays an important role in the rock cycle.

13. 15.1 Chemical Cycles
The Earth’s elements essential for living things are called nutrients.

14. 11.1 Why is Earth different?
Photosynthesis changed Earth’s atmosphere.

15. 11.1 Photosynthesis and the atmosphere
Photosynthesis converts carbon dioxide to oxygen in a process that allows living things use the sun’s energy.

16. 15.1 The carbon cycle
Trace the pathways through which carbon is released and absorbed in the diagram:

17. 11.2 The angle of the sun causes different climates
At the equator, sunlight is direct and intense.
As a result, the average yearly temperature at the equator is 27 °C (80 °F), while at the North Pole it is -18 °C (0 °F).

18. 15.2 Global climate change
Global climate change refers to changes in climate such as temperature, precipitation, or wind that last for two or more decades.

19. 15.2 The greenhouse effect
The greenhouse effect is the warming of Earth that results when Greenhouse gases trap heat:
water vapor, carbon dioxide, methane, nitrous oxide, ozone, and carbon compounds produced by industry.

20. 97% of scientists agree
CURRENT Global warming is human caused and real.
We’ll be discussing solutions the next few days…