Geologic Time Lecture
- 1. Geologic Time Chapters: 22,23,24
- 2. Earth’s Beginnings 4.6 billion years ago Collection of iron and gasses formed Rotation of cloud caused planet to form Settling of iron to core Early atmosphere formed Water vapor, carbon dioxide (CO 2 ) Modern atmosphere Nitrogen (78%), Oxygen (21%), Argon (1%)
- 3. Theories of Earth Science Uniformitarianism- Hutton- Small changes over a very long time. Examples: Catastrophism- Large changes over small periods of time. Examples:
- 4. Meteorites Crater Map Visual of crater
- 5. Geologic Time Scale Record of Earth’s History Eons- largest subdivision Eras- major subdivision Periods- Smallest divisions- made by types of life & geologic events.
- 6. Geologic Time Scale Con’t Epochs- smallest subdivision- Only found in Cenozoic Why??? What is our Eon, Era, Period and Epoch now??
- 7. Pre- Cambrian Time Oldest and Longest Time Period Almost 90% of Earth’s History From beginning of Earth (4.6 billion years ago) to 540 Million years ago Oldest rocks are the deepest rocks Ores are deposited (iron, silver, gold)
- 8. Pre-Cambrian Con’t Atmosphere develops oxygen How? Chemical reactions--- at least started process Cyanobacteria Earliest life Small (microscopic) blue-green algae Not even a plant yet Stromolites are their fossils Mass Extinction- Most of life dies (planets change) “an unusually large amount of species die in a short time
- 9. Phanerzoic Eon, Paleozoic Era Paleo- (Latin) ancient; -zoic (Latin) animals/ life Hard shelled animals appear Pangea formed Plants begin to grow on land “ Age of Fish” large fish populate oceans Amphibians (frogs) go to land Insects appear
- 10. Paleozoic Con’t Pennsylvanian Period- very large swamps which later become coal Appalachian Mountains Form
- 11. Mesozoic Era Meso- “middle” -zoic “animals/life” Breakup of Pangea Age of Reptiles- dinosaurs and reptiles rule planet Rocky Mountains form
- 12. Mass Extinction Dinosaurs are killed by meteorite Animals and plants change 90% of all species that have ever lived are now extinct
- 13. Cenozoic Era Ceno- “new”; -zoic “life” Last 45 million years Age of Mammals- Humans evolve Ice Ages Flowering Plants Colorado Plateau and Sierra Nevada Mountains formed
- 14. Organic Evolution Changes in the environment lead to changes in organisms Natural Selection- Certain traits make living in an environment easier Changes in Environment– Pangea moving -> climate -> plants ->animals
- 15. Extinctions Species dies no more living organisms Cause each major divide in time scale Dinosaurs- meteor, change in plants