Michigan Geologic Time Line List Rocks: www.educ.msu.edu/michiganrocks Student No. Event Age Geologic Time Name Division 1. Modern Humans .01 (10,000 Holocene years) 2. Ice Age Begins; Glaciers 2 million years Pleistocene cover all of Michigan; Great ago Lakes carved out by Glaciers 3. First Humans 4.5 million Pliocene years ago 4. First Horses 40 million years Eocene ago 5. Last Dinosaurs 65 million years /Tertiary ago Boundary 6. First Flowering Plants 100 million Cretaceous years ago 7. First Birds 150 million years ago 8. Redbeds (reddish 145 million Jurassic sandstones and shales) years ago deposited at the end of the Michigan Basin 9. First Mammals 215 million years ago 10. First Conifer Trees 230 million Triassic years ago 11. First Dinosaurs 240 million Triassic years ago 12. Last Trilobites 250 million /Triassic years ago Boundary 13. Swampland in Lower 290 million Pennsylvanian Peninsula and eastern years ago Upper Peninsula, Michigan Basin. Peat deposits. Also oil and gas deposits 14. First Reptiles 300 million Pennsylvanian years ago 15. Gypsum and Limestone 320 million Mississippian deposited in shallow seas in years ago Lower Peninsula and eastern Upper Peninsula – Michigan Basin 16. First Sharks 350 million years ago

Student No. Event Age Geologic Name Time Division 17. Hexagonaria coral deposits 360 million years Devonian (becomes MI state fossil aka ago Petosky Stone) in Michigan Basin 18. First Amphibians 370 million years Devonian ago 19. First Insects 400 million years Devonian ago 20. First Land Plants 420 million years ago 21. Salt deposited in shallow seas 430 million years Ordovician in southern Michigan in ago Michigan Basin 22. First Fish 480 million years Ordovician ago 23. Sandstones of the Pictures 500 million years Rocks National Lakeshore ago deposited in shallow seas; Beginning of the Michigan Basin 24. First Trilobites 550 million years Cambrian ago 25. First abundant fossils 600 million years Precambrian ago 26. Mountains as big as the Rocky 1.0 billion years Proterozoic Mountains in western Upper ago Peninsula 27. Oldest known fossil (algae) in 2.1 billion years Archean iron deposits probably similar ago to black smokers in oceans today 28. Volcanoes, basalt flows, pillow 2.8 billion years Archean lavas (lavas erupted in ocean ago water) 29. Metamorphic rocks of the 3.5 billion years Archean Canadian Shield, oldest rocks in ago Michigan, exposed in Western UP 30. Earth Formed 4.6 billion years Hadean ago