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Geologic Time Scale

Geologic Time Scale. Chapter 30. Division of Geologic Time. Geologic Time Scale: a summary of major events in Earth’s that are preserved in the in the rock record. Divided into four sub-categories. Eons Eras Periods Epochs. Division of Geologic Time. Eon: longest segment of geologic time.

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Geologic Time Scale

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  1. Geologic Time Scale Chapter 30

  2. Division of Geologic Time • Geologic Time Scale: a summary of major events in Earth’s that are preserved in the in the rock record. Divided into four sub-categories. • Eons • Eras • Periods • Epochs

  3. Division of Geologic Time Eon: longest segment of geologic time. • Archean (4bya) – Oldest/formation of Earth’s crust. • Proterozoic(2.5bya)- oldest fossils of simple ocean life. • Phanerozoic(543mya) – signs of visible life.

  4. Division of Geologic Time Phanerozoic Eon is subdivided into three ERAS: • Paleozoic (543mya) – fossils of ocean and land plants and animals (age of invertebrates). • Mesozoic (248mya) – Dinosaurs(age of reptiles) • Cenozoic (~65mya) – Last ice age and the (age of mammals) appearance of humans in the fossil record. Eras are divided into periods and periods into epochs.

  5. Changes through Geologic Time The Earth has undergone many changes through history. • Addition of O2 from mostly Co2, SO, intro of life, mountain/ocean formation…

  6. Evolution What is evolution? • It is the process of change that introduces new life forms. The mechanism in which this happened is called natural selection. This concept was introduced by Charles Darwin, a naturalist.

  7. Evolution. What is natural selection? • It’s the process by which organisms best suited to their environmental conditions are most likely to survive and reproduce.

  8. Kettlewell’s Research

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