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A Brief Look at Earth’s

The biological, geological, and climatic events listed appear in reverse chronological order, with the oldest (at the bottom) and the most recent event (at the top). Beginning of Major Biological Events Major Geologic and Climatic Events Period Interval of the Era of the Era or (10,000 ago) Earth’s climate has been stable for the 8,000 years. Recent Human Civilization Great Lakes formed as glacial ice melted. 1.7 million years ago The peak of the last ice was 21,000 years ago. (MYA) Saber-toothed Cats, Earth experienced several periods of glacial First Humans, conditions (ice ages) and interglacial conditions. , , Sloths ------ Tertiary Earth became colder and drier. Flowering Plants Volcanic activity increased in western North America. Horses, Cats, Dogs, Primates, Camels, Andes, Alps, and Himalaya Mountains formed as 66 MYA Rhinoceroses, Deer, Pigs, Small Mammals crustal plates moved. Colorado River carved out Grand Canyon. Inland seas in North America drained away. Extinction of Asteroid impact likely caused extinction of First Flowering Plants dinosaurs. Most Dinosaurs Rocky and Sierra Nevada Mountains formed. Larger, Fiercer Dinosaurs Climate was much warmer than today. First Birds Shallow seas covered much of North America. First Small Mammals Atlantic Ocean formed. Many Cycads and Conifer Trees North America and Africa moved apart. Reptiles Pangaea began to break up. 245 MYA First Dinosaurs Many Amphibians and Reptiles Land became drier. First Conifer Plants Basins were larger so water drained into them. First Reptiles Ural and Appalachian Mountains formed. Coal Forming Swamps Continents moved together, forming Pangaea. Coal formed in swampy regions. First Amphibians, Sharks and Insects Shallow seas covered most of land. Coral Reefs Form First Land Plants First Fish (Vertebrates) First Invertebrates; Trilobites, Brachiopods 570 MYA Simple Marine Life, Bacteria, Algae, Ozone layer formed. 4.6 billion years ago Jellyfish Outgassing caused the atmosphere to form and eventually the oceans. Meteorites bombarded Earth. Solid Earth divided into core, mantle, crust. Earth formed approximately 4.6 billion years ago. M.Y.A. = million years ago