The Geologic Time scale Mountain Eras Periods Building Life The prese nt CENOZOIC QUATERNARY Himal ayas Ma MESOZOIC TERTIARY Rocky Mins PALEOZOIC m y CRETACEOUS 1000 9Roubm ONo山 JURASSIC Birds 20 my La st Ou 2000 Tril obits PERMIAN UraLs Appalachians· Re piles CARBONIFEROUS 3000 DEVON IAN Sharks 400 des Northern First life Fossil SILURIAN Appalachia Continents Ide st ORDOVIC AN 4000 a corals CAMBRIAN 570 Trilobites