The Geological Time Scale NC Essential Standard

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The Geological Time ScaleNC Essential Standard
that the geologic time scale is a record of the
major events and diversity of life forms present
in Earths history. The geologic time scale began
when Earth was formed and goes on until the
present. At the end of each era a mass extinction
occurred, many kinds of organisms died out,
although there were other extinctions going on
during each period of geologic time. Using the
fossil record, paleontologists have created an
idea of the different types of common organisms
in each geologic period. o Precambrian Era ? The
Precambrian Era is Earth's first era of time. It
began with the creation of the Earth around 4.6
billion years ago. ? 5 major events occurred
during this era (1) the formation of the Sun and
light, (2) the creation of the Earth, (3) the
creation of the atmosphere through volcanic
out-gassing, (4) the creation of the oceans, and
(5) the creation of life. ? Began with simple
life forms such as bacteria and simple algae. ?
There was a rise of simple organisms such as
jellyfish and sea worms by the end of the era. ?
Few fossils because the life forms were
soft-bodied and had no hard skeleton. o Paleozoic
Era ? Began with the early invertebrates, such as
trilobites and brachiopods continued to develop
early vertebrate fish, then arachnids and
insects later came the first amphibians, and
near the eras end the reptiles became
dominant. ? Early land plants included simple
mosses, ferns, and then cone-bearing plants. ? By
the end of the era, seed plants were common. ?
The mass extinction that ended the era caused
most marine invertebrates as well as amphibians
to disappear. o Mesozoic Era ? Reptiles were the
dominant animals of this era, including the
various dinosaurs. ? Small mammals and birds also
appeared. ? Toward the end of the era, flowering
plants appeared and the kinds of mammals
increased. ? The mass extinction that ended the
era caused the dinosaurs to become extinct. o
Cenozoic Era ? New mammals appeared while others
became extinct. ? The diversity of life forms
increased. ? Flowering plants became most
common. ? Humans are also part of the most recent
period of this era
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• that a variety of artifacts are used to determine
  the geological history of the Earth, as well as
  how its life forms have changed over
• time. Ice cores are cylinders of ice that are
  drilled out of glaciers and polar ice sheets. Ice
  cores play an important role in helping
  scientists
• to gain an understanding of the Earths history,
  particularly how earths climate has changed over
  time. When snow falls it carries with it
• the compounds that are in the air at the time. In
  areas where temperatures are rarely above
  freezing (ice sheets and glacial areas), this
• builds up layer upon layer of compacted snow
  which becomes ice. Within these ice layers there
  is a record of the atmosphere at the time
• that the snow creating the ice layers fell.
• Sedimentary rock makes up about 75 of the rocks
  on the Earths surface. Sedimentary rocks form on
  the surface of the Earth, anywhere
• that sand, mud, or other types of sediment
  collect. Scientists can gain an understanding of
  Earths climate, biological, and geologic history
• by examining the contents of different layers of
  sedimentary rock. Sedimentary rock layers can be
  disturbed by igneous rock. This
• happens when molten rock forces it way up through
  the layers above it. This forms igneous rock
  sections within and across the
• sedimentary layers. The sedimentary rock layers
  must be there first, therefore the igneous rock
  intrusions are younger than the layers it cuts
• through. Sometime the molten rock will force its
  way to the surface and erupt, creating a younger
  igneous layer at the surface. With time,
• more sedimentary layers can form on top of the
  igneous rock. Igneous rock is always younger than
  rock layers it cuts through.
• ? that a fault is a break in the rocks that make
  up the Earths crust that is formed due to the
  movement of rock on either side of the
• fault. Generally, faults occur where there is
  movement (a slip) of tectonic plates. Sudden
  movement of this type is associated with
• earthquakes. Students know that the two main
  types of faults involve dip slips and strike
  slips. In a dip slip, two pieces of land change
• their vertical position compared to one another.
  Afterward, one side of the fault is higher than
  the other. In a strike slip, two pieces of land
• move horizontally.

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• diversity of life evident across geologic time.
  Through the illustrations, not only does the
  diversity of life-forms increase, but the
• complexity of those life-forms also increases.
• ? that millions of fossils have been collected
  and studied. The fossil record gives important
  information about past life and environments
• on Earth. Certain fossilized organisms could only
  live in specific environments or under particular
  climate conditions. Extinction of lifeforms
• as well as how and when new life-forms appeared
  is part of the fossil record.
• ? that the relative age means the age of one
  object compared to the age of another object.
  Relative age does not tell the exact age of an
• object. The relative age of rocks and fossils can
  be determined using two basic methods ordering
  of rock layers and index fossils
• o Ordering of Rock Layers Scientists read the
  rock layers knowing that each layer is deposited
  on top of other layers. The law of
• superposition states that each rock layer is
  older than the one above it. This law is used to
  read rock layers. Using this
• understanding of layering, scientists infer that
  the relative age of the rock or fossil in the
  rock is older if farther down in the rock
• layers. Relative dating is best used when the
  rock layers have been preserved in their original
  sequence. Over millions of years,
• tectonic plate motion can distort these layers.
  As a result of this, the youngest layers of rock
  are not always found on top, because of
• folding, breaking, and uplift of layers.
• o Index Fossils Certain fossils, called index
  fossils, can be used to help find the relative
  age of rock layers. To be an index fossil an
• organism must have lived only during a short part
  of Earths history many fossils of the organism
  must be found in rock layers the
• fossil must be found over a wide area of Earth
  the organism must be unique.
• The shorter time period a species lived, the
  better an index it is. A key example of an
  organism used as an index fossil are trilobites,
• a group of hard-shelled animals whose body had
  three sections, lived in shallow seas, and became
  extinct about 245 million years
• ago. Therefore, if a trilobite is found in a
  particular rock layer, it can be compared with
  trilobites from other layers to estimate the

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Events in Your Life

• Construct a timeline of the important events in
  your life. Be sure to include all of the events
  listed below and any other events you feel are
  important. Your timeline should be constructed
  TWO ways
• Numerical Order (use actual dates)
• Sequential Order (most recent at top)

• ___When you started second grade
• ___When you were born
• ___ When you started kindergarten
• ___When you learned to ride a bike.
• ___ When you learned to walk.
• ___ When you learned to read.
• ___ When you lost your first tooth.
• ___ Todays date.

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What is the Earths time scale?

• The Geological time scale is a record of the life
  forms and geological events in Earths history.
• Scientists developed the time scale by studying
  rock layers and fossils world wide.
• Radioactive dating helped determine the absolute
  divisions in the time scale.

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Divisions of Geologic Time

• Eras are subdivided into periods...periods are
  subdivided into epochs.

Era
Period
Epoch
E P EP
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Divisions of Geologic Time

• Geological time begins with Precambrian Time.
  Precambrian time covers approximately 88 of
  Earths history.

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FOUR Eras

• PRE-CAMBRIAN 88 of earths history
• Paleozoic (ancient life)
• 544 million years agolasted 300 million yrs
• Mesozoic (middle life)
• 245 million years agolasted 180 million yrs
• Cenozoic (recent life)
• 65 million years agocontinues through present day

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Today

• Today we are in the Holocene Epoch of the
  Quaternary Period of the Cenozoic Era.

Which unit is the largest? Which unit is the
smallest?
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• earliest of the geologic ages
• The Earth was already more than 600 million
  years old when life began. The planet had cooled
  down from its original molten state, developing a
  solid crust and oceans created from water vapor
  in the atmosphere

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• The earliest living organisms were microscopic
  bacteria, which show up in the fossil record as
  early as 3.4 billion years ago.
• Some three billion years ago the Earth's
  atmosphere was virtually devoid of oxygen. At
  about 2.4 billion years ago, oxygen was released
  from the seas as a byproduct of photosynthesis by
  cyanobacteria

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Extinct

• Dickinsonia

• Ediacarans

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Survived

• soft-bodied creatures were sponges
• cnidarians, which included sea anemones, corals,
  and jellyfish, had sac-like bodies
• the annelids, or segmented flatworms,

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• It's thought the final stages of Precambrian time
  were marked by a prolonged global ice age

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Paleozoic Era (Ancient Life)

• The Cambrian period is the 1st period of the
  Paleozoic Era. Age of the Trilobites
• Explosion of life in the oceans began during this
  era.
• Most of the continents were covered in warm,
  shallow seas.
• Invertebrates were dominate - Trilobites
• Fish emerged during this time
• Fish led to the arrival of amphibians
• The end of the Paleozoic era is called the Age
  of Amphibians
• Early land plants including mosses, ferns and
  cone-bearing plants.
• The early coal forming forests were also formed
  during this time.

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Paleozoic Era

• Much of the limestone quarried for building and
  industrial purposes, as well as the coal deposits
  of western Europe and the eastern United States,
  were formed during the Paleozoic.
• The Cambrian (beginning) opened with the breakup
  of the world-continent Rodinia and closed with
  the formation of Pangaea, as the Earth's
  continents came together once again.
• This event is thought to have caused the climate
  changes that led to mass extinction event.
• The Appalachian mountains were formed during this
  time.

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Paleozoic Era

• At the end of the Paleozoic, the largest mass
  extinction in history wiped out approximately 90
  of all marine animal species and 70 of land
  animals.
• Possible causes of this Mass Extinction Event
• Lowering of sea levels when the continents were
  rejoined as Pangaea (convergent boundary)
• Increased volcanic activity (ash and dust)
• Climate changes cooler climate

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Trilobites

• Lived in Earths ancient seas
• Extinct before the dinosaurs came into existence
• Cambrian Period is know as the Age of the
  Trilobites (put in on table)

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Brachiopods

• Marine animals that resemble clams.

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Early Fish
Early fish did not have jaws. Some species of
sharks were in existence at this time.
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Frilled Shark that was found in Japan in January
2007. This shark was considered a living fossil
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Early Land Plants
Mosses
Cone bearing plants
Ferns
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Mesozoic Era Middle Life

• At the beginning of this era the continents were
  joined as Pangaea.
• Pangaea broke up around the middle of this era.
• Reptiles became the most abundant animals because
  of their ability to adapt to the drier climate of
  the Mesozoic Era.
• Skin maintains body fluids
• Embryos live in shells

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Mesozoic Era

• Dinosaurs were also very active in this era.
• First small dinosaurs appeared in the Triassic
  Period.
• Larger and more abundant dinosaurs appeared in
  the Jurassic Period.
• Small mammals and birds also appeared during this
  era.
• The mammals were small, warm-blooded animals.
  Hair covering their bodies.
• These characteristics help them survive in
  changing environments.

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Mesozoic Era

• The main plant life of this time were Gymnosperms
  or plants that produce seeds, but no flowers.
• Pine Trees
• Flowering plants
• appeared during the
• END of this era.

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Mesozoic Era

• This era ended with a mass extinction event about
  65 million years ago.
• Many groups of animals, including the dinosaurs
  disappeared suddenly at this time.
• Many scientists believe that this event was
  caused by a comet or asteroid colliding with the
  Earth.

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Dinosaur Extinction

• https//www.youtube.com/watch?vY8Ij9xboreA

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Mesozoic Era Mass Extinction Event

• Asteroid or Comet collides with Earth.
• Huge cloud of smoke and dust fills the air
• Blocks out sunlight
• Plants die
• Animals that eat plants die
• Animals that eat plant-eaters die.
• However, not all forms of life died during this
  event. Many animals that you see today are
  descendants from the survivors of this extinction
  event.

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Mesozoic Reptiles
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Mesozoic Mammals
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Mesozoic Plants
Flowering plants evolved towards the end of the
Mesozoic Era.
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Cenozoic Era Recent Life

• Began about 65 million years ago and continues
  today!!!!!
• Climate was warm and mild.
• Marine animals such as whales and dolphins
  evolved.
• Mammals began to increase and evolve adaptations
  that allowed them to live in many different
  environments land, air and the sea.
• Grasses increased and provided a food source for
  grazing animals
• Many mountain ranges formed during the Cenozoic
  Era
• Alps in Europe and Himalayas in India Rocky
  Mountains in the USA

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Cenozoic Era

• Growth of these mountains may have helped to cool
  down the climate
• Ice Ages occurred late in the Cenozoic Era
  (Quaternary Period).
• As the climate changed, the animals had to adapt
  to the rise and fall of the oceans caused by
  melting glaciers.
• This era is sometimes called the Age of Mammals