Geologic Time
What is Geologic Time?
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A _____________ scale which divides geologic time into units.
Relative time is ________________ to something.
Units are from largest to smallest
o Eon  ______  Period  ______________  Age
Basis For Subdivision of Time
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Law of ___________________
Age of Earth ______ ______________ yrs oldest rock 4 billion yrs
_____________________
Precambrian Era
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Vast time in earth history _________ the deposition
of Cambrian _____________ bearing rocks.
Fossils are _____ because animals were ______ bodied.
Example: Jellyfish, paramecium, and trail marks from animals.
Plants & Animals
Paleozoic Era
Life increased in _______________
The continents collided to form
____________
Cambrian Period
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Also has “Age of __________” in it
Divided into ___-___ periods
1st common and ________________ fossils (index)
o example: Algae, sponges, worms, mollusks
 All lived in the Sea
o ________ large but few
o ______ :clams
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Cambrian Environment
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sea cucumbers
Ordovician Period 540 – 425 mya
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Rise of new ____________ groups of importance.
Oldest _________________- fragments of bone
o example: bryozoans, brachiopods, echnoids
Sea covered land
o ________ & _____________ building
Trilobites
Silurian Period 425-405 mya
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New ____________ rather than new groups of animals
Most important ___________ (fossil of oldest plant)
Trilobites, crinoids, etc. from ancient reefs near Chicago
types of ___________ starting
Crinoids
Environment
Devonian Period 405-345 mya
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Expansion of _______ and land plants
1st ______ animals (primitive amphibians)
First developed fish
o _____________ fish
o plate-skinned fish
o sharks
o 1st _________ fish
o From lobed-fin fish -amphibians
Oldest _________, millipedes and insects
Fresh water clams
Great ___________ starting
Coral reefs
Carboniferous 345-280 mya
Mississippian period 345-310 mya
o ______________ warm seas
o _____ animals and plants ___________
o Amphibians and land plants spread
o ______ swamp forests (most US under water)
Permian Period 280-230 mya
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Pennsylvanian Period 310-280 mya
Scale trees, seed ________ develop
_________ dragonflies
o (30 inch wing span)
Reptiles from amphibians
Primitive ___________________
New insects (beetles, and true dragonflies)
Active ________________
o different from skull and vertebrae fossil eggs
example:
o ____________-back lizard (sail as ________________ control)
o Theriodonts – carnivore ( mammals are descendents)
A lot become _________________ (trilobites, corals, blastoids)
Mesozoic Era
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Known as ______________ Life
Also has the “______ of the _____________” in it.
New pattern of lands and seas, formed _______________ ranges
Triassic Period 230-180 mya
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A lot of ____________ activity
_______________ dominate
o advanced body structure
o __________-protected eggs
o both _______ and __________ reptiles
1st appeared lobster like creature
______________ forest- Petrified forest
Jurassic Period 180-145 mya
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Flying reptiles and herbivores in water
__________ mammals-fragments of rat sized jaws & teeth.
Oldest known _______
Over thousand species of insects
Dinosaurs
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 3 main groups
_____________: long-necked, long-tailed, four-legged
o (largest land animal 87 ft long)
________________: armored reptiles, weighed up to 10 tons
_________________ Theropods: walk on ________ legs
Dinosaur Hips
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Dinosaurs are also classified by the _______ types of hips.
Saurischian- _____________ hipped
ornithischian- _________ hipped
Cretaceous Period 135-63 mya
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Major advanced of ________
________ arrivals- flowering plants, trees-magnolia, oaks, maple, etc.
New sources of food provided for mammals, birds, reptiles, and insects
_______________ roamed over all continents
____________ mammals, marsupials
At the ________ of period _________________ of dinosaurs.
Cenozoic Era 63-1 mya (last 70 my)
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_______ Periods and __________ epochs
Includes the age of the ________________
Includes the age of Man
Birds are numerous
______________ fish dominate
Our era of ___________
Tertiary Period
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Has __________ epochs.
A lot of changes taking place
examples:
o -___________ mammals to _____________ mammals
o -_____________ plants to _______________
o -Single animals to __________
-Alps, Himalayas, Rockies, Andes and Glacier formation
Paleocene Epoch
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Mammals are _________
____________ plants
Eocene Epoch
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Mammals becoming _______________
Ancestors of modern ____________ and
_____________
Oligocene Epoch
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________________ plants _____________ by grasses and pines
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Apes, elephants, cats and dogs families
Miocene Epoch
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__________ of grass eating animals
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Land bridge between ___________ and ______________Mastodans cross.
Pliocene Epoch
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____________began to form
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Sea level ________
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Animals crossed __________ bridges and new land formed
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Animals hunting herds
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(Near End of Epoch)
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Ice age ________________
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___________ _______________ was carved out of rising rock layers
Quaternary Period
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Includes _______ Epochs
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Climate much ___________
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Includes the __________ Age
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Includes the age of _______
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Our period of ________________
Pleistocene Epoch
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_________ mya Ice Age
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___________________ advanced at least _________ different times
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Animals either developed ________________ covering or moved
__________
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example: mastodons, saber-tooth tigers, ________________
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(At end of the epoch)
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10,000 yrs ago Ice sheets __________________
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Large mammals became _________________
Holocene Epoch
Earth’s climate became ______________
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Human civilization arose (Age of man)
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The epoch of _______________