Chapter 2, Section 3 – Unit A Science 8 Messana

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

Geological Time - really, really, really long! Motion pictures are generally projected at 32 frames per second. Therefore, each frame (image) is on the screen for only split second- let each frame represent 100 years. Start movie at present and go back in time. The Declaration of Independence would show up 1/16 of a second into the movie. The Christian era (BC-AD boundary) would be 3/4 of a second into the movie. The most recent Ice Age would be 7 seconds into it. The movie would run about 6 hours before we got to the end of the Mesozoic era (extinction of the dinosaurs). We'd have to watch the movie for about 2 days to see the beginning of the Paleozoic era (macroscopic life). The whole movie (to the beginning of geologic time on Earth) would be approximately 16 days long! Motion pictures are generally projected at 32 frames per second. Therefore, each frame (image) is on the screen for only split second- let each frame represent 100 years. Start movie at present and go back in time. The Declaration of Independence would show up 1/16 of a second into the movie. The Christian era (BC-AD boundary) would be 3/4 of a second into the movie. The most recent Ice Age would be 7 seconds into it. The movie would run about 6 hours before we got to the end of the Mesozoic era (extinction of the dinosaurs). We'd have to watch the movie for about 2 days to see the beginning of the Paleozoic era (macroscopic life). The whole movie (to the beginning of geologic time on Earth) would be approximately 16 days long!

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 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?

 Eon: the longest division of geological time.  Era: a major division of geological time; an era is usually divided into two or more periods. (most recent eon = 3 eras)  Period: Each era is subdivided into a # of periods  Epoch: smallest division of time; a subdivision of a period

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

 1. Hadean  2. Archean  3. Proterozoic  4. Phanerozoic  Eons #1-3 make up Precambrian Time (90% of Earth’s History) Largest to Smallest amounts of TIME….  Eons -> Eras -> Periods -> Epochs  Change in name is due major geologic or climatic events!

 Most of Earth’s history…  OR  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! Turn Paper Please!!

 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”

 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  EVOLUTION –is beginning to emerge!

 248 mya – 65 mya  PANGAEA- begins to break apart (about 200 million yrs ago!!!  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

 65 mya – Present  Large warm-blooded mammals, modern birds, flowering plants  Animals developed migration techniques  Tertiary Period  Quaternary PERIOD= Past 2 million yrs ◦ Ice ages ◦ 1 st modern human fossils = 100,000 yrs old ◦ Humans are 7 seconds of 12 hour clock!! :0

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