A Brief Look at Earth’s History The biological, geological, and climatic events listed appear in reverse chronological order, with the oldest event (at the bottom) and the most recent event (at the top). Era Beginning of Major Biological Events Major Geologic and Climatic Events Period Epoch Interval of the Era of the Era Quaternary Holocene or (10,000 years ago) Earth’s climate has been stable for the past 8,000 years. Recent Human Civilization Great Lakes formed as glacial ice melted. Pleistocene 1.7 million years ago The peak of the last ice age was 21,000 years ago. (MYA) Saber-toothed Cats, Earth experienced several periods of glacial First Humans, conditions (ice ages) and interglacial conditions. Bears, Mammoths, Sloths ---------------------------------- Cenozoic Tertiary Pliocene Earth became colder and drier. Miocene Flowering Plants Volcanic activity increased in western North America. Oligocene Horses, Cats, Dogs, Primates, Camels, Andes, Alps, and Himalaya Mountains formed as Eocene 66 MYA Rhinoceroses, Deer, Pigs, Small Mammals crustal plates moved. Paleocene Colorado River carved out Grand Canyon. Inland seas in North America drained away. Cretaceous Extinction of Dinosaurs Asteroid impact likely caused extinction of First Flowering Plants dinosaurs. Most Dinosaurs Rocky and Sierra Nevada Mountains formed. Jurassic Larger, Fiercer Dinosaurs Climate was much warmer than today. Mesozoic First Birds Shallow seas covered much of North America. First Small Mammals Atlantic Ocean formed. Triassic Many Cycads and Conifer Trees North America and Africa moved apart. Reptiles Pangaea began to break up. 245 MYA First Dinosaurs Permian Many Amphibians and Reptiles Land became drier. First Conifer Plants Basins were larger so water drained into them. Carboniferous First Reptiles Ural and Appalachian Mountains formed. Pennsylvanian Coal Forming Swamps Continents moved together, forming Pangaea. Mississippian Coal formed in swampy regions. Paleozoic Devonian First Amphibians, Sharks and Insects Shallow seas covered most of land. Silurian Coral Reefs Form First Land Plants Ordovician First Fish (Vertebrates) Cambrian 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 Precambrian 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 .