| Time
(Myr ago) |
Event |
| 4600 | Formation of the approximately homogeneous solid Earth by planetesimal accretion |
| 4300 | Melting of the Earth due to radioactive and gravitational heating which leads to its differentiated interior structure as well as outgassing of molecules such as water, methane, ammonia, hydrogen, nitrogen, and carbon dioxide |
| 4300 | Atmospheric water is photodissociated by ultraviolet light to give oxygen atoms which are incorporated into an ozone layer and hydrogen molecules which escape into space |
| 4000 | Bombardment of the Earth by planetesimals stops |
| 3800 | The Earth's crust solidifies--formation of the oldest 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 algae which releases oxygen molecules into the atmosphere and steadily works to strengthen the ozone layer and change the Earth's chemically reducing atmosphere into a chemically oxidizing one |
| 2400 | Rise in the concentration of oxygen molecules stops the deposition of uraninites (since they are soluble when combined with oxygen) and starts the deposition of banded iron formations |
| 2000 | The Oklo natural fission reactor in Gabon goes into operation |
| 1600 | The last reserves of reduced iron are used up by the increasing atmospheric oxygen--last banded iron formations |
| 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 plate tectonic 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 and beginning 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 roughly 60 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 from southeastern Asia and North America from northeastern Asia |
| 0.025-0.01 | Most recent glaciation--an ice sheet covers much of the northern United States |
| 0.02 | Homo sapiens sapiens paint the Altamira Cave |
| 0.012 | Homo sapiens sapiens have domesticated dogs in Kirkuk, Iraq |
| 0.01 | First permanent Homo sapiens sapiens settlements |
| 0.01 | Homo sapiens sapiens learn to use fire to cast copper 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 | ||
| Paleozoic era | 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 | ||
| Mesozoic era | Triassic period | 250-205 | |
| Jurassic period | 205-135 | ||
| Cretaceous period | 135-65 | ||
| Cenozoic
era "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 | ||
| Quarternary period | 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