- By carefully analyzing landforms, rocks and fossils - A fossil of an animal that was around on earth at a particular time in history The history of the earth from its formation to the present. The earths history maybe divided into several major time periods, called ERAS. - A time of major sediment deposition and earth movement Before history 4, 600 m.y. Lasted 4 b.y. Birth of Earth 4.6 b.y - Moon forms 4.5 b.y. when a large asteroid hits earth causing pieces to fly out into space - Earths surface solidifies 4.4 b.y. and cools - Over time the earths core gets hot and starts the process of Plate Tectonics - Gases released from volcanoes condenses into clouds and it rains on earth. - Rainwater created the oceans (formed 4.4 4.2 b.y) - Early atmosphere forms 4.0 b.y. (no living organisms on land) - Formation of the Canadian Shield m above sea level - About 1.2 b.y. continents assembled intoRodinia - First life 4.0 b.y. in the oceans - First Cyanobacteria - Stromatolites (living reefs) released O2 into the atmosphere - Oxygenated atmosphere forms 2.4 b.y. - 1 st single celled organisms (algae) in water environment - 1 st mutli-celled organisms - Jellies 580 m.y - Primitive life forms oldlife 570 m.y. 325 m.y. - Age of fish and amphibians - 1 st insects - Large swamps (coal formed from this vegetation) - 1 st plants & animals appear on land - Arthropods 535 m.y.(80% of all living species - means jointed legs) - Trilobites 525 m.y. - Cambrian explosion (appearance of many new species) - Echinoderms 525 m.y. - Ordovician m.y.a - True land plants arise, leafless at first 470 m.y. - Jawed fish 425 m.y. - Horseshoe crabs 400 m.y.(1 st to leave the sea) - Amphibians 370 m.y. - Carnifers 315 m.y. - Reptiles 310 m.y. - Scales and skin protect reptiles. Spikes serve as camouflage and defence - Great change rocks the earth; continents go dry, results in mass extiniction 250 m.y. - N.A covered by shallow seas - Appalachians formed (300 million years ago) middle life 245 m.y. 180 m.y. - Age of reptiles dinosaurs be.com/watch? v=OfHdYcKDh6 A&feature=rela ted Planet Dinosaur - 1 st flowering plants - 1 st birds & mammals (warm-blooded) - 1 st birds 150 m.y. - Cretaceous 146 65 m.y.a. - Ants 130 m.y Co-evolution entwines insects and birds with plants forever - - Formation of the rocky mountains begin - - Innuition mountains formed - - Shallow seas in the interior of N. America at various times - - Formation of the rocky mountains begin - - Innuition mountains formed - - Shallow seas in the interior of N. America at various times recent life 66 m.y - Modern forms of life evolve - Age of mammals - Human being develop - Primates evolve in jungle 55 m.y - Tarsiers believed to be linking links to a branch of early primates who evolved in the rainforests 50 m.y. - Whales 50 m.y. - Long-bodied land mammals with hoofed feet turned into marine creatures - Elephants 50 m.y. - Last of the great mega-herbivores that once roamed the earth on all continents except Antarctica - Sea Lions 20 m.y. Quaternary 1.8 mya - today - Homo-erectus 2 my Ice Age 100, 000 10, 000 yrs Modern Humans 0.2 m.y - Ice sheets cover much of N.A - Formation of rocky mountains complete - Coast mountains form and complete - Continents take their present shape