The Geologic Time Scale
description
Transcript of The Geologic Time Scale
THE GEOLOGICTIME SCALE
MASS EXTINCTIONS• 99.9% of all living things that have ever existed on earth have gone extinct• earth has experienced 5 five extinctions
GEOLOGIC TIME SCALEEra• Largest unit of geologic time • lasts tens to hundreds of millions of years and
consists of two or more periods. Period• Divides Eras• Most commonly used units of time scale• Lasts millions of years• Each is associated with a particular rock systemEpochs• Divide Periods• Smallest unit of geologic time• Lasts several million years
PRE CAMBRIAN
Life Climate/AtmosphereBacteria,sponges
• CH4, NH3, H2, C• Volcanic eruptions,
lightening• Some areas freeze
PALEOZOIC ERA
CAMBRIAN544-505 MYA
Life Climate/Atmosphere• “Cambrian Explosion” =
jellyfish, starfish, worms, sea scorpions
• Trilobites dominant
• Warm/tropical• No glaciation
ORDOVICIAN505-440 MYA
Life Climate/Atmosphere• Mass extinctions of
marine life• Invertebrates dominant
• Starfish, clams, oysters, squids, octopuses
• Land masses gather at south pole
• Massive glacier form dropping sea levels
SILURIAN440-410 MYA
Life Climate/Atmosphere
• Earliest land plants• First Jawfishes • Trilobites, sea scorpions,
mollusks still common
• Pangea forms• Tropical climate• Glaciers melt• Ocean rises• Warm shallow seas
form
DEVONIAN410-360 MYA
Life Climate/Atmosphere
• First sharks, amphibians, insects, and trees
• Extinction of armored fish
• Very warm
CARBONIFEROUS360-286 MYA
Life Climate/Atmosphere• Amphibians, winged
insects, small reptiles, and conifers and ferns
• Warm tropical areas• Glaciers at poles
PERMIAN286 – 245 MYA
Life Climate/Atmosphere• Centipedes, spiders, and
cockroaches • Seed plants• Reptiles abundant• Beetles first appear• Many inverts go extinct
• Temperatures increase• Sea levels rise
MESOZOIC ERA
TRIASSIC245-208 MYA
Life Climate/Atmosphere• Turtles, crocodiles, and
lizards appear• Sharks, sea urchins,
seastars are abundant• Early dinosaurs (ex.
placodont)
• Sea levels rise• land is very dry and
hot. • glaciers melting.
JURASSIC208-146 MYA
Life Climate/Atmosphere• Insects, sharks, crocodiles,
and fish are abundant• The earliest mammals
appear. • Early dinosaurs are abundant
• Hot• No glaciers
CRETACEOUS146-65 MYA
Life Climate/Atmosphere• “Age of the
Dinosaurs”• Flowering plants
and bees
• Pangea splits apart creating more coastline• Seasons begin to form
CENOZOIC ERA
TERTIARY65-1.8 MYA
Life Climate/Atmosphere•“Age of Mammals”•Grasslands, forests, palm trees, kelp forests•Birds evolve
•Started tropical and then started to cool•Continents crashed into each other creating mountains
QUARTERNARY1.8 MYA- PRESENT
Life Climate/Atmosphere•First appearance of woolly mammoth, giant sloth, saber-toothed cats
•Went through an ice age•Temps warmed and continue to