Welcome To Class
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Agenda
• Turn in homework• Geologic time scale
– Notes
• Fossil Reading 2• Review for test
Geologic Time• If time was a 30 day month• Recorded human history would be .18 minutes
or 10.8 seconds• First Homo sapiens would be .013 days or 18.72
minutes or 1123.2 seconds• Cenozoic would be .42 days or 604 minutes• Mesozoic would be 1.18 days or 1700 minutes• Paleozoic would be 1.95 days or 2808 minutes• Precambrian would 26.4 days or 38106 minutes
http://www.athro.com/geo/hgfr1.html
In a day…
• Human history = 2.5 seconds• Home sapiens = .6 minutes• Cenozoic = 20.2 minutes• Mesozoic= 56.5 minutes• Paleozoic= 93.6 minutes• Precambrian= 1269.7 minutes
Geologic Time Scale
• Geologic time scale – chart that divides Earth’s history into units of time
• Divisions based on geologic events and major changes in living things
Geologic Time Scale
Divided into eons, eras, and periods
PRECAMBRIAN TIME
Length– beginning of time (4.6 billion yrs) – 542 million years ago
Makes up 88% of Earth’s history
Precambrian Time
• Major Events– Earth forms– Rocks and minerals form– Stromatolites (algae) are most
common fossils
PALEOZOIC ERA
Paleozoic Era
• Length – 542 – 251 million years ago
• Major Events– Supercontinent, Pangea, formed– Shelled marine animals common– Land Plants and animals appear– Fish, amphibians, reptiles appear– Permian mass extinction
Paleozoic Broken Down
• Cambrian• Ordovician• Silurian• Devonian• Carboniferous
– Mississippian– Pennsylvanian
• Permian
MESOZOIC ERA
Mesozoic Era
• Length – 251-65 million years ago– Age of the Dinosaurs
• Major Events– Pangea broke up– Dinosaurs– First Birds– First flowers– Dinosaur extinction
Mesozoic Broken Down
• Periods in the Mesozoic– Triassic– Jurassic– Cretaceous
CENOZOIC ERA
Cenozoic Era
• Length – 65 million years ago-present– Age of mammals
• Major Events– Mammals appear– Continents in current places– First humans
Cenozoic Broken Down
• Tertiary– Paleocene– Eocene– Oligocene– Miocene– Piliocene
• Quaternary– Pleistocene– Holocene
Fossil Reading
• Due today
Review
• Worksheet due on test day
• Create a Note card (tomorrow)
Which are the oldest?
• Remember the laws/principles/unconformities– Law of Superposition– Principle of Original Horizontality– 3 Unconformities– Law of Cross Cutting Relationships
Absolute Age
• Radiometric/carbon dating
• Half life
Interpret a half life graph
5.8 days
.25 half lives
28 years
Review
• Work on the worksheet– Due on the TEST!!– Create a note card
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