Precambrian Time
Precambrian time includes two eons: Archaean and Proterozoic. It encompasses 90% of the Earth's history.
The Archaean eon includes four eras: Eoarchean (Greek = ancient), Paleoarchean (Greek = old), Mesoarchean (Greek = middle), and Neoarchean (Greek = new). The Archaean eon lasted around 2.5 billion years. During this eon, the atmosphere, ocean, continents, and bacteria formed.
The Proterozoic eon includes three eras: Paleoproterozoic (Greek = old), Mesoproterozoic (Greek = middle), and Neoproterozoic (Greek = new). The Proterozoic eon lasted around 2 billion years. During this eon, multicellular organisms formed, and there was oxygen build-up.
Earth 700 Million Years Ago (Precambrian)
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At this time, animals had not yet appeared. Mostly, the continents were gathered into one of two super-continents. In between these two super-continents was a narrow ocean.
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Earth 650 Million Years Ago (Precambrian)
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At this time, the northern super-continent had drifted away from the southern super-continent. New ocean floor was created between them. Only Sponges had appeared by this time.
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Earth 600 Million Years Ago (Precambrian)
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Around this time, Jellyfish had appeared in the oceans. The northern super-continent had now turned around and was headed towards the southern super-continent.
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Earth 550 Million Years Ago (Cambrian)
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At this time in the southern super-continent, North America had started drifting away from South America. Many of the main animal groups had now appeared, which include worms, molluscs, and arthropods. Precambrian time ands and the Paleozoic Era begins.
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The Seas 542-488 Million Years Ago
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Earth 500 Million Years Ago (Ordovician)
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North America was now heading across the ocean. This was the end of the Cambrian period. The animal world was still dominated by invertebrates.
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Earth 450 Million Years Ago (Silurian)
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North America continued its long passage across the ocean. As the continents were far apart and were not colliding, they were low and mostly covered by shallow seas. At this time, the world's first vertebrates had appeared,
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Earth 400 Million Years Ago (Silurian/Devonian)
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There was a great collision of continents during this time. After its long journey across the ocean, North America and Greenland collide with Europe, which created the mountains we now find in Scotland, Greenland, and Norway. Meanwhile, Gondwanaland rested over the South Pole (click on link below to view). Jawed fish had now appeared.
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Earth 350 Million Years Ago (Carboniferous)
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More mountains were formed by the colliding of North America into Europe and Siberia. One of the greatest mass extinctions of all time occurred in this period. It devastated marine life. Entire communities os sea invertebrates were wiped out. This may have been cause by an ice age that happened around this time.
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Earth 300 Million Years Ago (Permian)
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The collision of North America with Europe and Siberia, which started 100 million years earlier, was completed and the super-continent of Laurasia was formed, consisting of North America, Greenland, the Baltics, France and Siberia. Also during this time, Laurasia collided with much of Gondwanaland, which created the new super-continent of Pangaea. A narrow channel, called the Tethys Sea separated the two land masses. Northern and Southern China were still separated from Pangaea. By this time, plants, invertebrates, and vertebrates had left the sea and begun to live on land.
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Earth 250 Million Years Ago (Triassic)
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The many collisions that created Pangaea produced many mountain ranges, including the Appalachians and Urals. Around this time, many plants and animals died. Some believe it may have been caused by an ice age that occurred due to Gondwanaland's position over the South Pole (click on link below to view). The early dinosaurs, crocodiles, and turtles arrive. The Paleozoic Era ends and the Mesozoic Era begins.
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Earth 200 Million Years Ago (Jurassic)
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Around this time, Pangaea started to break up, and its bits drifted around. All of this continental movement had a great impact on the evolution of life. For example, Australia and South America were once part of one large island, separated from the other continents. That is why we find animals called marsupials in both these places but nowhere else. Also at this time, seagoing reptiles, large dinosaurs, flying reptiles (pterosaurs), and the earliest known birds arrived.
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Earth 150 Million Years Ago (Cretaceous)
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The break up of Pangaea became more obvious. The Tethys Sea widened between Laurasia (in the north) and Gondwanaland (in the south). South America, Africa, and Antarctica were still joined in Gondwanaland. Birds were flying, plants had flowers and mammals had appeared by this time. Dinosaurs rule the land, and seed-bearing plants appear.
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Earth 100 Million Years Ago (Cretaceous / Paleogene)
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Since continents were now separating instead of colliding, there were few high mountains. This was the Cretaceous period. The continents moved towards their present positions. Dinosaurs still ruled the land. Flowering plants continued to evolve. India began its journey away from Antarctica and towards Afghanistan (click on link below to view). Soon, the Mesozoic Era will end and the Cenozoic Era begins.
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Earth 50 Million Years Ago (Paleogene / Neogene)
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The Rocky and Sierra Nevada mountains were formed as North America moved westward. Similar westward movement of South America produced the Andes. India continued to move northwards towards Afghanistan (click on link below to view).
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Earth Present Day (Neogene)
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Today we are in a period of active mountain building. The Himalayas were built over the past 50 million years. The Rockies and Andes are continuing to grow as North and South America move west over the sea floor. The Japanese and other island chains grow as the floor of the Pacific ocean dives under the Asian continent.
Source(s): www.historyoftheuniverse.com;
www.freestockphotos.biz;
www.infoplease.com;
/museumvictoria.com.au/melbournemuseum/discoverycentre/600-million-years/timeline/cambrian/
www.freestockphotos.biz;
www.infoplease.com;
/museumvictoria.com.au/melbournemuseum/discoverycentre/600-million-years/timeline/cambrian/