-Hadean Eon

      -Archean Eon

      -Proterozoic Eon

      -Phanerozoic Eon

-Began with the formation of Earth by planetesimal accretion

      -Age of meteorites

      -Mars size planet hit the earth, and the debris from collision formed a ring around     the Earth, creating the moon

      -Was close, now far away

      -A molten surface, uninhabitable

      -First oceans created due to rain

-3.8 Ga Earth cooled from lithosphere

      -Plate tectonics

                  -Many small microplates

                  -Archean lithosphere was too hot to subduct

      -Continental crust formed when low-density felsic rocks formed above subduction zones 

-90% of Earth's continental crust

      -Grew by addition of volcanic arcs

      -Continents cooled and strengthened to become cratons

-Paleozoic - ancient

 -Mesozoic - middle

      -Cenozoic - recent

-Continents rifted and developed passive margins

      -Rising seas flooded expanses of continental crust

      -Rifting of Pannotia led to 4 large continental fragments

-Silurian climate warmed and created greenhouse conditions

      -Devonian: microcontinent Avalon was welded onto North America

      -Created the Antler orogenic belt

      -New species replaced those lost to extinction

      -Land plants changed earth

      -Fish rapidly evolved

      -The first land animals followed plants

      -The first amphibians appeared

-Dense tropical wetland hosted vegetation and giant insects

      -Reptiles appeared for the first time

-90% of all marine species disappeared

            -Some believe a large impact

-First ancestors of mammals appear at Trassic

-By end of Triassic, dinosaurs appeared!

-Corals

      -Gymnosperms

      -Reptiles diversified

-By end of Jurassic, sauropods were abundant

-First feathered birds

-Climate warms and seas flood the continents

      -Pangaea breaks up

      -Uplifts in Colorado - Laramide orogeny, reverse faulting

-Fish appear

      -Swimming reptiles

      -Angiosperms appear

      -Dino's reached evolutionary peak

      -Mammals had larger brains and specialized teeth

-Sudden mass extinction

      -Dinosaurs gone, 90% plankton gone, 75% plant species vanished

      -Catastrophic impact

-Final stages of breakup of Pangaea

            -Climate has cooled

-2Ma to present - cool climate

      -Not the only ice age

-After K-T boundary, plant life is recovered

      -Forests of angiosperms reappear

      -Birds diversify and spread

      -Known as age of mammals

-Late Cenozoic humans first appeared

      -First humanlike primate 4Ma

      -First member of genes Homo appeared at 2.4Ma

      -Modern humans appeared 150Ka

The Geologic Time Scale

Earliest to Most Recent

1. Hadean

2. Archean

3. Proterozoic

4. Phanerozoic

   -Paleozoic

      -Cambrian

      -Silurian

      -Devonian

   -Mesozoic

      -Triassic

      -Jurassic

      -Cretaceous

   -Cenozoic