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Periods
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EPOCH
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Cenozoic
Era
(65 mya to today)
(Recent Life)
Age of Mammals
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Quaternary
(1.8 mya to today)
| Modern man radiates, "science" appears. |
Holocene
(11,000 years to today) |
| Neandertals appear and disappear; Homo erectus and Homo sapiens appear. Saber-toothed cats, mammoths, and mastodons become extict. |
Pleistocene
(1.8 mya to 11,000 yrs) |
Tertiary
(65 to 1.8 mya)
K-T Boundary
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(Hominids), the australopithecines. |
Pliocene
(5 to 1.8 mya) |
| Grazing horses, antelopes appear. Sierra Nevada mountains built with uplifting. |
Miocene
(23 to 5 mya) |
| Most modern bird forms and mammals have appeared. |
Oligocene
(38 to 23 mya) |
| First grasses appear, a resource for herbovores; trees thrive. Some modern mammals appear: advanced primates; camels, cats, dogs, horses & rodents.
Himalayan Mountains formed from the collision
of India with the Eurasian plate. |
(OEB)
Eocene
(54 to 37 mya) |
| Small mammals radiate.
| Paleocene
(65 to 54 mya) |
Mesozoic
Era
(245 to 65 mya)
(Middle Life)
The age of Reptiles.
P-T Boundary
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Cretaceous
(146 to 65 mya)
- flowering plants (angiosperms); lizards; placental animals (early mammals); snakes; social insects; marsupial and primitive placental animals. Primitave primates.
Modern insect forms radiate. N. America separates from Europe. Major extinction includes dinosaurs and ammonites. (K-T). |
Divided
as:
Upper;
Middle;
Lower
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| Jurassic
(208 to 146 mya)
- Birds; crabs; frogs and salamanders
Dinosaurs radiate to dominate the land. Pangaea is broken into two large continents Laurasia and Gondwanaland. Mountains in western north America started to be built with plate techtonics and volcanic eruptions. |
| Triassic
(245 to 208 mya)
- Breakup of Pangaea begins - Dinosaurs; crocodiles; marine reptiles; turtles; Pterosauria and mammals
Major groups of seed plants appear. Modern ferns. |
Paleozoic
Era
(544 to 245 mya)
(Ancient Life)
Age of Invertebrates. Complex plants and animals burst into life as part of The Cambrian Explosion.
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Permian
(286 to 245 mya)
- Seedplants producing large trees. Major extinction of invertebrates (P-T)
Supercontinent of Pangaea is complete. |
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Carboniferous
(360 to 286 mya)
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Pennsylvanian
(325 to 286 mya)
- Conifers & many winged insects appear.
Use of eggs by some life forms.
Supercontinent of Gondwanaland collides with the combination of Laurentia and Baltica - now known as Laurussia (Appalachian orogeny 310-250 mya) and creates the Great Smoky Mountains, the Appalachians, and the Cevennes of France. Around the same time another small continent, here called Angaria, collided with Baltica's eastern margin, uplifting the Ural Mountains. |
Mississippian
(360 to 325 mya)
- amphibians move from sea to land. Reptiles appear |
| Devonian
(410 to 360 mya) - Land colonized by plants and animals
Appearances include: insects; sharks; amphibians (tetrapods); lung fishes and earliest seed plants. Fish begin to dominate the seas. Continents continue to collide initially in what is now the Maritime Provinces of Canada (Acadian orogeny 410-350 mya) and creates a range of mountains extended from the Adirondacks north through Nova Scotia, the British Isles, Norway and the eastern margin of Greenland.
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| Silurian
(440 to 410 mya) - Jawed fish, cartilaginous fish and vascular plants appear. Primitive terrestrial predators. |
| Ordovician
(500 to 440 mya)
- First land plants. Continents of Laurentia and Baltica collided (Taconic orogeny 480-440 mya) creating Taconic mountains in NY.
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| Cambrian
(544 to 500 mya) - vertebrates; jawless fish; small shelly animals; conodonts; trilobites |
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| Neoproterozoic Era
(1000 to 544 mya) - Macroscopic fossils of soft-bodied organisms. Continent of Rodinia breaks up. |
Ediacaran (Vendian)
(600 to 544 mya) - Oldest metazoans (multicellular animals)
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Cryogenian (850-600)
Earth covered with ice that was a mile thick.
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| Tonian (1000-850)
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| Mesoproterozoic Era
(1.6 to 1 bya) - Sexual reproduction appears -
First land fungi. Giant Continent Rodinia created. Continental collisions (Grenville Orogeny) created initial mountains in the New York Bight. Outcroppings of granite from this period still protrude out of the forest in Harriman State Park. |
| Paleoproterozoic Era
(2.5 to 1.6 bya) - More complex single-celled life - cyanobacteria (blue-green algae) oxygenating the atmosphere. |
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Archaean(3.8 to 2.5 bya) First Life, Oldest Fossils, Stromatolite
- First life was bacterial.
Early microbes thrive in an oxygen-free environment, feeding on organic molecules like glucose and producing energy in a process called fermentation. As populations grow and food supplies become scarce, bacteria that can generate their own food and energy evolve. Many of them use a process known as photosynthesis, converting energy radiated from the sun into chemical energy the organism can store and use.
Cyanobacteria (blue-green algae) evolve 3.3 bya and use photosynthesis, which uses carbon dioxide and releases oxygen molecules changing the Earth's atmosphere to an oxygen rich one from 2.7-2.2 bya.
As several chunks of smaller land blocks collide, the earliest continents form. About 2,500 mya, the continents join together to form the first supercontinent. Scientific evidence suggests the planet's major continents have come together only four or five times.
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| Hadean Time (4.5 to 3.8 bya) - Sometime during the first 800 million or so years of its history, the surface of the Earth changed from liquid (molten rock) to solid. Erosion and plate tectonics has probably destroyed most of the solid rocks that were older than 3.8 billion years.
For many years, there was no direct evidence to challenge that picture. But in the early 1980s came the discovery in Western Australia of single grains of an extremely durable mineral crystal known as zircon. Even after they are recycled through countless generations of rock, zircon crystals retain hints about the physical and chemical conditions in which they formed.
See Ancient Crystals Suggest Earlier Ocean
4,055 mya - Oldest rocks, Granite. Found in what is now Canada's Northwest Territories. Granite is lighter than other rocks and would float up to the surface.
Gases released from magma inside Earth collect to form an atmosphere probably composed of nitrogen (N2), Carbon Dioxide (CO2), carbon monoxide (CO), water vapor (H2O); They may have combined to form some ammonia (NH3) and methane (CH4) also, although this theory is disputed now. THere was little or no free oxygen. (Newer schemes exclude ammonia and methane.)
4,200 mya - Water condenses in the cooling atmosphere, and heavy rains pour down on the planet. After several hundred million years of falling rain, great oceans form.
4,055 mya - First rocks.
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mya: Million Years Ago
History
