Origin of the Earth & Geologic Time
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The document summarizes the formation and early history of Earth and life: 1) Around 4.6 billion years ago, Earth formed from a cloud of dust and gas left over from the creation of the Sun. 2) Life first emerged around 3.8-2.5 billion years ago in the form of primitive microbes like cyanobacteria and archea. 3) The first soft-bodied animals appeared around 543 million years ago, marking the end of the Proterozoic Eon and the beginning of complex life on Earth.
Origin of the Earth & Geologic Time
- 1. The Origin of our Solar System and the Earth
- 2. It’s in the stars… Nebula – an interstellar cloud of dust, hydrogen gas, helium gas and other ionized particles. The gas, dust and other materials in the nebula collide and condense to form a larger mass, this process produces a great deal of heat, thus the star is formed. Due to the gravitational pull of the star, the remaining nebula organizes itself into accretion discs (rings of dust and gasses). Orion Nebula
- 3. Eagle Nebula
- 5. Solar Nebular Hypothesis
- 6. EARTH’S EARLIEST TIME: THE PRECAMBRIAN Earth’s formation, along with the other planets, is projected to have happened 4.6 billion years ago from a solidified cloud of dust and gasses left over from the creation of the Sun.
- 7. THE FIRST EON: HADEAN Earth's formation by accretion from the solar nebula, 4.6 billion years ago bombardment by meteorites volcanism must have been severe Earth changed from liquid to solid
- 8. THE SECOND EON: ARCHEAN 3.8 to 2.5 billion years ago Earth cooled significantly An atmosphere formed which lacked oxygen and an ozone layer but likely contained methane, ammonia, and other gases which would be toxic to most life on our planet today. primordial life began to evolve: stromatolites, such as cyanobacteria (blue-green algae) and archea (bacteria that can survive in extreme conditions)
- 9. Stromatolites Heterocyst – Nitrogen Fixation Photosynthetic Cells Cyanobacteria
- 10. THE THIRD EON: PROTEROZOIC started 2.5 billion years ago and ended 543 million years ago stable land masses first appeared oxygen build-up in the atmosphere prokaryotic bacteria and the four eukaryotic kingdoms (plants, animals, fungi, & protists) end of proterozoic: first soft-bodied animals (fossil evidence)
- 11. Hadean Era (4600 to 3800 mya) – 800 million yrs Archaean Era (3800 to 2500 mya) - 1.3 billion yrs Proterozoic Era (2500 to 543 mya) - 1.96 billion yrs Precambrian (4,500 to 543 mya) - 3.96 billion yrs
- 12. You can think of the Precambrian time as the earliest time of earth formation and the first forms of life on it. You can liken it to a pregnancy in which basic elements and life forces form the infant. Once the infant is born, we speak of a human life time. Earth’s Life Time is called the PHANEROZOIC EON. Earth’s life time can be divided into old age, medieval (middle) age, and young age Paleozoic Mesozoic Cenozoic
- 13. Permian (290 to 248 mya) Pennsylvanian (323 to 290 mya) Mississippian (354 to 323 mya) ( Carboniferous) Devonian (417 to 354 mya) Silurian (443 to 417 mya) Ordovician (490 to 443 mya) Cambrian (543 to 490 mya) Paleozoic Era -old age- (543 to 248 mya) -295 million yrs Cretaceous (144 to 65 mya) Jurassic (206 to 144 mya) Triassic (248 to 206 mya) Mesozoic Era -middle age- (248 to 65 mya) - 183 million yrs Period: Quaternary (1.8 mya to today) Tertiary (65 to 1.8 mya) Cenozoic Era -young age- (65 mya to today) - 65 million yrs Phanerozoic Eon (543 mya to present)
- 14. Carboniferous What happened in the Paleozoic Era? 90% of all marine animal species became extinct (oil and limestone) tremendous mountain building (platechtonic movement) retreats of shallow seas abundance of primitive plants in the Carboniferous time trilobites were abundant and then became extinct Pangaea formed, Panthalassa, Tethys Sea 7 Periods : Permian (290 to 248 mya) Pennsylvanian (323 to 290 mya) Mississippian (354 to 323 mya) Devonian(417 to 354 mya) Silurian(443 to 417 mya) Ordovician (490 to 443 mya) Cambrian (543 to 490 mya) Paleozoic Era -age of old life- (543 to 248 mya)
- 15. Paleozoic Era
- 16. Trilobites!
- 17. PANGAEA = one continent PANTHALASSA TETHYS SEA
- 18. What happened in the Mesozoic Era? dinosaurs evolved in the Triassic dinosaurs diversified until the Jurassic dinosaurs became extinct by the end of the Cretaceous (last dinosaurs to have lived are found in the late Cretaceous deposits of Montana in the United States fauna changed: trees and flowering plants appeared tectonic plates move to present location 3 Periods : Cretaceous (144 to 65 mya) Jurassic (206 to 144 mya) Triassic (248 to 206 mya) Mesozoic Era -age of medieval life- (248 to 65 mya)
- 19. The Age of Reptiles
- 20. Mesozoic Era
- 23. 2 Periods : Quaternary (1.8 mya to today) Holocene (10,000 years to today) relative warm period; homo sapiens sapiens Pleistocene (1.8 mya to 10,000 yrs) humans spread in the world most continents covered with glaciers= ice age mammoths prevalent and then extinct Tertiary (65 to 1.8 mya) Pliocene (5.3 to 1.8 mya) Antarctic polar cap formed Miocene (23.8 to 5.3 mya) many grasses; kelp forests Oligocene ( 33.7 to 23.8 mya) first elephants with trunks, early horses Eocene (54.8 to 33.7 mya) small hoofed animals (ungulates) Paleocene (65 to 54.8 mya) starting point for the great evolution of mammals Cenozoic Era -age of young life- (65 mya to today)
- 24. Cenozoic Era
- 26. The Breakup of Pangaea
- 27. Break-up of Pangaea in the different Eras: LAURASIA BREAKS UP GONDWANALAND BREAKS UP PANGAEA BREAKS INTO LAURASIA and GONDWANALAND One supercontinent: PANGAEA
Editor's Notes
- #10: Modern Stromatolites found at Hamelin Pool, Western Australia. Cyanobacteria have heterocyst for nitrogen fixation and cells for photosynthesis. The photosynthesis produces the byproduct oxygen which was instrumental in building an oxygen rich environment in the Precambrian time.
- #16: Illinois flat lands home to carboniferous rainforest 300 million years ago. Ferns made up a large portion of vegetation during this period. Also thought of at the Golden Age of sharks…with evolution of fish into much of the shapes and types we see today. Most dominant insect was the cockroach, fossil finds size it up to 3.5 inches in the carboniferous era. First vertebrates (lampreys)