1. Chapter 2, Section 3 – Unit A Science 8 Messana

2.  What did you decide was more useful…tree rings or ice cores?  Why?

3.  Geologic Time Scale – a timeline of Earth’s History divided into periods of time by major events or changes on Earth What do we call these major events or changes?

4. Catastrophic Events – events that cause major destruction or change life completely Examples:  Mass extinctions  Ice Ages  Meteors  Major volcanic eruptions

5.  1. Hadean  2. Archean  3. Proterozoic  4. Phanerozoic  #1-3 make up Precambrian Time  Eons -> Eras -> Periods -> Epochs  Change in name is due major geologic or climatic events!!

6.  90% of Earth’s history  Lasted nearly 4 billion years of Earth’s 4.6 billion years  Volcanic ash & dust ->clouds formed ->rain  Single-celled micro-organisms in ocean at end  No animals  No plants

7.  544 million years ago – present  Explosion of Life!  3 Eras: ◦ Paleozoic Era – “Age of Amphibians” ◦ Mesozoic Era – “Age of Dinosaurs” ◦ Cenozoic Era – “Age of Mammals”

8.  544 mya – 248 mya  All life in ocean until end  Fish developed  Reptiles, Insects, Ferns developed – moving life onto land at end  Ends with a Mass Extinction (from a meteor strike?)– kills 90% of all ocean species

9.  248 mya – 65 mya  Dinosaurs rule!  Small mammals, birds, flowering plants  Ends with Mass Extinction due to meteor strike off Mexico ->dust cloud blocked sunlight, killed plant life and affected food chain

10.  65 mya – Present  Large warm-blooded mammals, modern birds, flowering plants  Animals developed migration techniques  Tertiary Period  Quaternary Period = last 2 million yrs ◦ Ice ages ◦ 1 st modern human fossils = 100,000 yrs old ◦ Humans are ? seconds of 12 hour clock!! :0

13.  Earth is constantly changing due to the same basic forces  EX:Slow = erosion, plate movement Fast = volcano, earthquake