| Time (Myr ago) | Event |
| 4600 | Formation of the approximately homogeneoussolid Earth by planetesimal accretion |
| 4300 | Melting of the Earth due to radioactive andgravitational heating which leads to itsdifferentiated interior structure aswell as outgassing of molecules such aswater, methane, ammonia, hydrogen, nitrogen,and carbon dioxide |
| 4300 | Atmospheric water is photodissociated by ultravioletlight to give oxygen atoms which are incorporatedinto an ozone layer and hydrogen molecules whichescape into space |
| 4000 | Bombardment of the Earth by planetesimals stops |
| 3800 | The Earth's crust solidifies--formation of theoldest rocks found on Earth |
| 3800 | Condensation of atmospheric water into oceans |
| 3500-2800 | Prokaryotic cell organisms develop |
| 3500-2800 | Beginning of photosynthesis by blue-green algaewhich releases oxygen molecules into the atmosphereand steadily works to strengthen the ozone layerand change the Earth's chemically reducing atmosphereinto a chemically oxidizing one |
| 1600 | The last reserves of reduced iron are used up by theincreasing atmospheric oxygen--last banded ironformations |
| 1500 | Eukaryotic cell organisms develop |
| 1500-600 | Rise of multicellular organisms |
| 580-545 | Fossils of Ediacaran organisms are made |
| 545 | Cambrian explosion of hard-bodied organisms |
| 528-526 | Fossilization of the Chengjiang site |
| 517-515 | Fossilization of the Burgess Shale |
| 500-450 | Rise of the fish--first vertebrates |
| 430 | Waxy coated algae begin to live on land |
| 420 | Millipedes have evolved--first land animals |
| 375 | The Appalachian mountains are formed via a platetectonic collision between North America, Africa,and Europe |
| 375 | Appearance of primitive sharks |
| 350-300 | Rise of the amphibians |
| 350 | Primitive insects have evolved |
| 350 | Primitive ferns evolve--first plants with roots |
| 300-200 | Rise of the reptiles |
| 300 | Winged insects have evolved |
| 280 | Beetles and weevils have evolved |
| 250 | Permian period mass extinction |
| 230 | Roaches and termites have evolved |
| 225 | Modern ferns have evolved |
| 225 | Bees have evolved |
| 200 | Pangaea starts to break apart |
| 200 | Primitive crocodiles have evolved |
| 200 | Appearance of mammals |
| 145 | Archaeopteryx walks the Earth |
| 136 | Primitive kangaroos have evolved |
| 100 | Primitive cranes have evolved |
| 90 | Modern sharks have evolved |
| 65 | K-T Boundary--extinction of the dinosaurs andbeginning of the reign of mammals |
| 60 | Rats, mice, and squirrels have evolved |
| 60 | Herons and storks have evolved |
| 55 | Rabbits and hares have evolved |
| 50 | Primitive monkeys have evolved |
| 28 | Koalas have evolved |
| 20 | Parrots and pigeons have evolved |
| 20-12 | The chimpanzee and hominid lines evolve |
| 10-4 | Ramapithecus exist |
| 4 | Development of hominid bipedalism |
| 4-1 | Australopithecus exist |
| 3.5 | The Australopithecus Lucy walks the Earth |
| 2 | Widespread use of stone tools |
| 2-0.01 | Most recent ice age |
| 1.6-0.2 | Homo erectus exist |
| 1-0.5 | Homo erectus tames fire |
| 0.3 | Geminga supernova explosion at a distance of roughly60 pc--roughly as bright as the Moon |
| 0.2-0.03 | Homo sapiens neanderthalensis exist |
| 0.05-0 | Homo sapiens sapiens exist |
| 0.04-0.012 | Homo sapiens sapiens enter Australia fromsoutheastern Asia and North America from northeastern Asia |
| 0.025-0.01 | Most recent glaciation--an ice sheet covers muchof the northern United States |
| 0.02 | Homo sapiens sapiens paint the Altamira Cave |
| 0.012 | Homo sapiens sapiens have domesticated dogs inKirkuk, Iraq |
| 0.01 | First permanent Homo sapiens sapiens settlements |
| 0.01 | Homo sapiens sapiens learn to use fire to castcopper and harden pottery |
| 0.006 | Writing is developed in Sumeria |
| Era/Period/Epoch | Time (Myr ago) | ||
| Archaeozoic (Archean)era | 5000-1500 | ||
| Proterozoic era | 1500-545 | ||
| Paleozoicera | Cambrian period | 545-505 | |
| Ordovician period | 505-438 | ||
| Silurian period | 438-410 | ||
| Devonian period | 410-355 | ||
| Carboniferous(Mississipian/Pennsylvanian) period | 355-290 | ||
| Permian period | 290-250 | ||
| Mesozoicera | Triassic period | 250-205 | |
| Jurassic period | 205-135 | ||
| Cretaceous period | 135-65 | ||
| Cenozoicera "Recent Life" | Tertiary period | Paleocene epoch | 65-55 |
| Eocene epoch | 55-38 | ||
| Oligocene epoch | 38-26 | ||
| Miocene epoch | 26-6 | ||
| Pliocene epoch | 6-1.8 | ||
| Quarternaryperiod | Pleistocene epoch | 1.8-0.01 | |
| (Lower Paleolithic) | 0.50-0.25 | ||
| (Middle Paleolithic) | 0.25-0.06 | ||
| (Upper Paleolithic) | 0.06-0.01 | ||
| Holocene epoch | 0.01-0 | ||
Taken from http://www.talkorigins.org/origins/geo_timeline.html
Return to Lecture 22