Geologic Time Table

Holocene

Begin-10,000 years EndToday EraCenozoic PeriodQuaternary

Recession of glaciers; extinction of megafauna; dominance of mankind.

Pleistocene

Begin-2 My End-10,000 years EraCenozoic PeriodQuaternary

Glacial episodes and ice ages. More mammals develop, including the now extinct saber-toothed tiger and the mastodon. Modern man appears.

Pliocene

Begin-5 My End-2 My EraCenozoic PeriodTertiary

Monkeys and australopithecines.

Miocene

Begin-24 My End-5 My EraCenozoic PeriodTertiary

Rise of Colorado Plateau; formation of Basin and Range; beginning of mankind. Horses, dogs, bears, modern whales, South American monkeys, modern birds. Ramapithecus appears.

Oligocene

Begin-37 My End-24 My EraCenozoic PeriodTertiary

Pigs, rhinoceros, and tapirs.

Eocene

Begin-58 My End-37 My EraCenozoic PeriodTertiary

Rodents and primates evolve. Whales and horses appear.

Paleocene

Begin-65 My End-58 My EraCenozoic PeriodTertiary

Recovery from Cretaceous terminal event; ascendence of mammals; rise of Rockies; dinosaurs, pterosaurs, and ammonites extinct; rise of modern animals; shrubs, grasses, and other flowering plants. Mammals such as camels, bears, cats, monkeys, rodents, and dogs develop. Grasses and fruit develop similar to what we have today.

Cretaceous

Begin-140 My End-65 My EraMesozoic PeriodCretaceous

Dominance of dinosaurs; flowering plants; primates; evolution of birds; Rockies begin to rise; sea level stands at Fall Line; demise of dinosaurs and other large animals at end, probably resulting from Chicxulub impact (K-T terminal event). First angiosperm plants; Mesozoic reptiles peak of development, as well as the downfall of the great dinosaurs. Triceratops, Tyrannosaurus Rex, and the giant Pterodactyl.

Jurassic

Begin-200 My End-140 My EraMesozoic PeriodJurassic

Beginning of birds; Pangea splits; Atlantic Ocean widens. Ferns, cycads, ginkgos, rushes, conifers, ammonites, lobster, shrimp, shellfish and other invertebrates; pterosaurs, archaeopteryx appears, giant dinosaurs develop, as well as abundant plant life.

Triassic

Begin-250 My End-200 My EraMesozoic PeriodTriassic

Pangea begins to split; Atlantic Ocean opens; invertebrates pervade; reptiles dominant: turtles, dinosaurs, ichthyosaurs. Beginning of dinosaurs, both plant and meat eaters, flying reptiles and crocodiles.

Permian

Begin-290 My End-250 My EraPaleozoic PeriodPermian

Pangea intact; no Atlantic Ocean; demise of many marine animals; evolution of reptiles. Trilobites extinct; amphibians and reptiles dominant land animals; gymnosperms dominant plants. Molluscs dominate the seas. At the end of the Paleozoic, the Permo-Triassic extinction event wiped out approximately 90% of all marine animal species. Reptiles become abundant. Trees similar to pine develop.

Pennsylvanian

Begin-320 My End-290 My EraPaleozoic PeriodPennsylvanian

Iapetus Ocean closes; Pangea coalesces; coal swamps; reptiles; the beds of the Cumberland Plateau are laid down.

Mississippian

Begin-360 My End-320 My EraPaleozoic PeriodMississippian

Fern forests; sharks; the Highland Rim in Tennessee and Kentucky. Foraminiferans, corals, bryozoans, brachiopods, blastoids; seed ferns are plentiful, lycopsids, and other plants; amphibians become more common. The first reptiles evolve from amphibians. Spiders, cockroaches, scorpions appear. First animals to live on dry land.

Devonian

Begin-410 My End-360 My EraPaleozoic PeriodDevonian

Insects; amphibians; corals, brachiopods, ammonoids, crinoids and early land plants. Fish evolve into more complex animals, sharks and amphibians multiply.

Silurian

Begin-440 My End-410 My EraPaleozoic PeriodSilurian

Vascular land plants, the first true plants appear; air-breathing animals; brachiopods, corals, primitive fish. Crinoids are abundant, and eurypterids, believed to be the first air-breathing animal, appear.

Ordovician

Begin-500 My End-440 My EraPaleozoic PeriodOrdovician

Fish; corals; the Nashville Basin. Graptolites dominant; also trilobites, brachiopods, bryozoans, gastropods, bivalves, echinoids, crinoids, cephalopods, and corals. Graptolites, Orthoceras, and primitive fish, the first vertebrates, begin to appear.

Cambrian

Begin-600 My End-500 My EraPaleozoic PeriodCambrian

Proliferation of multi-cellular life; first marine animals with mineralized shells appear: trilobites, echinoderms, brachiopods, arthropods, molluscs, primitive graptolites; a variety of worms, algae, and many invertebrates similar to jellyfish and worms. The first shelled animals begin to appear.

Pre-Cambrian

Begin-4500 My End-600 My EraPre-Cambrian PeriodPre-Cambrian

Formation of Earth's crust; multiple tectonic cycles; oldest dated crustal rocks, -3900 My. Beginnings of life; oldest evidence for life, -3800 My. Iapetus Ocean begins to open near one end. During this time, the Earth formed, life arose, the first tectonic plates arose and began to move, eukaryotic cells evolved, the first oxygen/ozone layer formed around -2000 My, and just before the end of the Precambrian, complex multicellular organisms, including the first animals, evolved.