GEOLOGICAL TIME SCALE

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GEOLOGICAL TIME SCALE

• Section 18.1,18.2 By Christian Flores and Jordan

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Section Objections

• Summarize the development of the geologic column.
• List the major units of geologic time.
• identify the characteristics of Precambrian rock
• Explain what scientists have learned from the
  geological record about life during the Paleozoic
  era.
• Explain what scientist have learned from the
  geologic record about life during the Cenozoic
  era.

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New Vocabulary

• Cenozoic Era- The most recent geologic era,
  beginning 65 million years ago the Age of
  Mammals.
• Epoch- Subdivision of a geologic period.
• Era- Largest unit of geologic time.
• Geologic Column- Arrangement of rock layers based
  on the ages of the rocks.
• Invertebrate- An animal without a backbone
• Mesozoic Era- Geologic era that lasted from 245
  million years ago the Age of Reptiles.
• Paleozoic Era- Geologic era that followed
  Precambrian time, lasting from 570 million to 245
  million years ago.
• Period- Subdivision of a geologic era.
• Precambrian Time- earliest and longest geologic
  era lasting from 4.6 billion to 570 million years
  ago.
• Theory Of Evolution- Theory that organisms are
  derived from ancestral types.
• Vertebrate- An animal with a back bone.

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The Geologic Column

• Using the law of superposition and the study of
  index fossils, nineteenth-century scientists
  determined the relative ages of rock layers in
  the areas throughout the world. No single area on
  the earth contained a record of all geologic
  time.
• Scientist combined their observations from around
  the world to create a standard arrangement of
  rock layers called now the geologic column.
• Rock layers in the geologic column are
  distinguished by the fossils they contain and the
  rock type.

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Divisions of Geologic Time

• Is divided into units.
• Geologist use events like earths geologic
  history, major changes in the earths surface or
  climate changes to dived them into units.
• A unit is often characterized by fossils of a
  dominant life-form.

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Eras

• A very large unit of geologic time is an era.
• Earliest is Precambrian Era. It is known more as
  Precambrian time because it is much longer then
  other geologic eras. When this era started
  earths crust was just beginning to solidify. It
  lasted for 4.6 billion years
• Paleozoic Era followed Precambrian time. It means
  ancient life. It lasted 325 million years. They
  contain fossils of marine and land plants and
  animals.
• Mesozoic Era followed the Paleozoic Era. It
  means middle life. These fossil's contain more
  complex forms. It lasted 180 million years.
• The Cenozoic Era followed the Mesozoic Era. It
  means recent life. The fossils of mammals are
  common in this era. This era started 65 million
  years ago and still continues today.

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Periods and Epochs

• Eras have been divided into shorter times called
  periods. Each period is characterized by specific
  fossils and usually named for the location in
  which the rocks containing the identifying
  fossils.
• Epochs are even shorter time periods then periods.

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Precambrian Time

• Began nearly 4.6 billion years ago and ended 570
  million years ago.
• It makes nearly 88 of earths history.
• Large areas of exposed rock Precambrian rocks,
  called shields are found in every continent, one
  of these shields covers much of eastern Canada.
• Fossils are rare in Precambrian rocks because the
  life forms used to have soft bodied. These
  organisms lacked bones, shells and other hard
  parts needed to make a fossils.

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The Paleozoic era

• Began 570 million years ago ended 245 millions
  years ago
• Had Cambrian period, Ordovician period, Silurian
  Period, Devonian Period, Carboniferous Period,
  Permian Period.

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The Mesozoic Era

• Began 245 million years ago ended 65 million
  years ago.
• Had Triassic Period, Jurassic Period, and
  Cretaceous Period.

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The Cenozoic Era

• Began 65 million years ago and it still continues
  today.
• Had Quaternary Period, and Tertiary Period.
• Also had these epochs Holocene, Pleistocene,
  Pliocene, Miocene, Oligocene, Eocene, Paleocene.

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The End