The Geologic Time Scale Sections of time ERA

The Geologic Time Scale

Sections of time • ERA Two or more geological periods comprise an era, which is hundreds of millions of years in duration.

• PERIOD The period is the basic unit of geological time in which a single type of rock system is formed, lasting tens of millions of years. EPOCH An epoch is a division of a geologic period; it is the smallest division of geologic time, lasting several million years.

• Eon- Era- Period- Epoch- Age. • Humans as we know ourselves appeared in the Pleistocene Epoch of the Quaternary Period in the Cenozoic era of the Phanerozoic Eon…. .

Pre Cambrian time • 4. 6 Billion years ago 542 MA • Earth Forms • Stromatolites are dominant life form

Paleozoic Era • 542 to 251 mya • Multicellular life!!

Paleozoic, Cambrian, • • 488 -542 MA Trilobites dominate many phyla develop. “Cambrian Explosion”

Paleozoic, Ordovician, • 488 to 444 mya • North America is under shallow sea. • Modern Oxygen rich atmosphere develops • Vertebrates Develop

Paleozoic, Silurian • 444 MA 416 MA • First Land Plants and Animals

Paleozoic, Devonian, • 416 MA -359 MA • First amphibians • Age of fishes

Paleozoic, Carboniferius, Missippian • 359 MA – 318 MA • Amphibians Flourish • Forests and swamps cover land

Paleozoic, Carboniferius, Pennsylvanian • 318 MA – 299 MA • Giant flying insects • First Reptiles, ROAR!!

Paleozoic, Permian • 299 MA – 251 MA • Pangea comes together

Mesozoic Era • "The Age of Reptiles" 251 MA to 65. 5 MA

Mesozoic, Triassic • 251 MA – 200 MA • Dinosaurs appear • Mammals appear

• Cycads and conifers dominate

Mesozoic, Jurassic • 200 MA- 146 MA • Dinosaurs are the dominant animal. • Primitive vertebrate flight, first birds

Mesozoic, Cretaceous, • 146 -65. 5 MA • Flowering plants appear (angiosperms) • Modern Birds • All good until……

K-T Extinction • • 65 MA Kills off Dinosaurs Asteroid or volcano Iridium rich dust….

Cenozoic Era "The Age of Mammals" 65. 5 mya through today Continents at present locations

Cenozoic, Tertiary, Paleocene Tertiary 65 -55. 8 mya Paleocene- age on mammals begins First Primates

Cenozoic, Tertiary, Eocene • 55. 8 -33. 9 mya • Rodents appear. Primitive whales appear.

Cenozoic, Tertiary, Oligocene • 33. 9 -23 mya • Dogs and cats appear! • But they did not look like that -

Cenozoic, Tertiary, Miocene • 23 -5. 3 MA • Due to high abundance of grasses, herds of large mammals abound.

Cenozoic, Tertiary, Pliocene • 5. 3 -1. 8 • First hominids (australopithecines). Modern forms of whales. Megalodon swam the seas • Hominid- where humans and apes split

• Lions Tigers and Bears…. • Appear in the Pliocene

Cenozoic, Quauernary, Pleistocene • Quaternary Period "The Age of Man" 1. 8 mya to today • Pleistocene- The Last Ice Age 1. 8 -. 012 ma • Humans (Homo sapien) appear. You better remember this!

• Mammoths, sabertoothed cats,

Quaternary, Holocene • 11, 500 ya to today • Marked by complex human civilization • Ice melted, and sea level rose 140 m!