Jan 24, 2016
- A scale that subdivides the 4.5-billion-year history of Earth into many different units and provides a meaningful time frame within which the events of the geologic past are arranged.
EON ERA PERIOD EPOCH
PHANEROZOIC
CENOZOIC
QUATERNARY HOLOCENE
PLEISTOCENE
TERTIARY PLIOCENE
MIOCENE
OLIGOCENE
EOCENE
PALEOCENE
MESOZOIC CRETACEOUS “Age of Reptiles”JURASSIC
TRIASSIC
PALEOZOIC
PERMIAN “Age of Amphibians”CARBONI-
FEROUSPENNSYLVANIAN
MISSISSIPPIAN
DEVONIAN “Age of Fishes”SILURIAN
ORDOVICIAN “Age of Invertebrates”CAMBRIAN
PRECAMBRIAN
EON• Two or more geological eras
form an Eon, which is the largest division of geologic time, lasting many hundreds of millions of years.
PRECAMBRIAN- means: "before the Cambrian
period." - From 4.6 billion years ago to the
beginning of the Cambrian Period (about 570 mya)
- It is actually composed of three Eons: HADEAN, ARCHEAN, AND PROTEROZOIC.
- The Precambrian represents about 88 % of the Geologic Time.
HADEAN EON• Hadean ("Hades-like") Eon. • 4.5 to 3.9 billion years ago• During this era the surface of the Earth was
like popular visions about Hades: oceans of liquid rock, boiling sulfur, and impact craters everywhere.
HADEAN EARTH("Hades-like")
ARCHEAN EON• Archean ("Ancient" or "Primitive") Eon.• 3.9 to 2.5 billion years ago• This eon began about a billion years after the
formation of the earth, and things have changed a lot! Mostly everything has cooled down. Most of the water vapor that was in the air has cooled and condensed to form a global ocean.
ARCHEAN EARTH("Ancient" or "Primitive")
The first life forms evolve - one celled organisms.
The cyanobacteria or "blue-green algae," have left a fossil record that extends far back into the Precambrian - the oldest cyanobacteria-like fossils known are nearly 3.5 billion years old, among the oldest fossils currently
known.
PROTEROZOIC EON
• 2.5 billion years ago to 540 mya• First multicellular life: colonial
algae and soft-bodied invertebrates appear. Oxygen build-up in the Mid-Proterozoic.
PROTEROZOIC EARTH("Early Life")
PHANEROZOIC EON- Is derived from Greek words
meaning visible life.- It is an appropriate description
because the rocks and deposits of the Phanerozoic eon contain abundant fossils that document major evolutionary trends.
- It is composed of three eras: PALEOZOIC, MESOZOIC, and CENOZOIC.
ERA• Two or more geological
periods comprise an era, which is hundreds of millions of years in duration.
PALEOZOIC ERA• Paleo = ancient zoe = life• 540 to 248 mya • At its beginning, multicelled animals
underwent a dramatic "explosion" in diversity, and almost all living animal phyla appeared within a few millions of years.
• At the other end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all marine animal species.
MESOZOIC ERA
• Meso = Middle zoe = life• "THE AGE OF REPTILES"• from 248 million to 65 million
years ago.
• The continents were jammed together at the beginning of the Mesozoic Era, forming the supercontinent of Pangaea, but would start breaking apart toward the middle of the Mesozoic Era.
CENOZOIC ERA• Ceno = recent zoe = life• 65 Million Years to the Present• sometimes called the “Age of
Mammals”
PERIODThe period is the basic unit of geological time in which a single type of rock system is formed, lasting tens of millions of years.
PALEOZOIC ERAPERMIAN
CARBONIFEROUS PENNSYLVANIAN
MISSISSIPPIAN
DEVONIAN
SILURIAN
ORDOVICIAN
CAMBRIAN
MESOZOIC ERA
CRETACEOUS
JURASSIC
TRIASSIC
CENOZOIC ERA
•QUATERNARY•TERTIARY