Earths History

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Earths History
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Formation of Sun

• Formation of Universe 13 billion years
• Formation of Galaxy 11 billion Years
• Formation of Solar System 4.6 billion years
• Sun is probably a third generation star
• Probably takes 10-100 million years for planets
  to form

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Formation of Planets

• Planets made of same material as Sun, minus
  elements that remain mostly in gases
• Inner Rocky Planets iron and magnesium silicates
  
• Outer gas giants and moons water ice
• Very far from sun methane, ammonia, nitrogen ice

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Formation of Earth

• Planets formed by accretion of smaller objects
  impact
• Very tiny objects hold together by atomic forces
• Objects kilometers across hold together by
  gravity
• How do objects the size of a refrigerator hold
  together?
• As planets get bigger, gravity gets stronger,
  impacts get more violent
• Big impacts throw out ejecta, trap heat
• Magma ocean
• Formation of core early in earth history as iron
  sinks

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Formation of Moon

• It's very hard to account for the Moon
• Very big compared to its parent planet
• Orbits nearly in plane of earth's orbit, not over
  equator.
• Co-creation with Earth?

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Unstable Early Earth

• May have been several moon-forming events
• 1000-km impactors can melt crust
• 100-km impactors create temporary atmosphere of
  vaporized rock, vaporize oceans
• Life not possible until large impacts cease
• To have life on Earth, we need Jupiter?
• Sweeps up debris and reduces impacts
• Stabilizes orbits of other planets
• To have life on Earth, we need Moon?
• Stabilizes changes in earth's axis tilt

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Conditions on Early Earth

• Oldest existing earth materials 4.1 billion
  years old
• Oldest rocks 3.9 billion years old
• Oxygen-poor atmosphere (present oxygen is created
  by life)
• Faint Early Sun perhaps 30 per cent less bright
• Evidence for liquid water from very early on
• Atmosphere and sun must have evolved in tandem

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How The Earth Works
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Earth Systems

• Geosphere
• Rock Cycle
• Plate Tectonics
• Biosphere
• Atmosphere
• Cryosphere
• Hydrosphere

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GEOSPHERE
The geosphere is the solid Earth that includes
continental and oceanic crust as well as the
various layers of the Earth's interior. Ninety-fou
r percent of the earth is composed of the
elements oxygen, iron, silica, and magnesium.
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The Solid Earth

• Core-solid in the center, molten outside layer,
  mostly Fe with a little nickel
• Mantle-thick, solid
• Athenosphere-inner zone partially molten
• Crusts-outer most, thin layer
• 8 elements-98.5
• fossil fuels minerals

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The Rock Cycle

• New Rocks Exposed by Erosion
• Rocks Broken Down Mechanically and Chemically
  (Weathering)
• Components Transported by Erosion
• Components Cemented into Sedimentary Rocks
• Burial and Heating creates Metamorphic Rocks
• Melting Creates Igneous Rocks

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The Rock Cycle
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Plate Tectonics

• The geospheres surface (crust) is in a constant
  state of motion that gives rise to movement of
  the continents.
• The unifying theory that explains how continental
  drift is possible is called plate tectonics,
  which was developed by geologists in the 1960s.
• Supercontinents
• Rodinia 800 million years
• Gondwana
• Laurasia
• Pangaea 250 million years, only lasted 70 million
  years

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Biosphere

• The biosphere is the
• life zone of the Earth
• and includes all living
• organisms, including
• man, and all organic matter that has not yet
• decomposed. Life evolved on earth during its
  early
• history between 4.5 and 3.8 billion years go and
  the
• biosphere readily distinguishes our planet from
  all others in the solar system

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Life

• What Is It?
• "Life is what dies when you stomp on it"--Dave
  Barry
• A self-replicating chemical system

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How Did Life Originate?

• Certainly not as complex as anything now alive
• Lots of candidates for first self-replicators
• Role of minerals as catalysts and templates?
• Simplest organisms are extremophiles
• At least since 3 billion years, probably much
  earlier

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Major Events in the History of Life

• Oxygen levels in atmosphere
• Plants release waste oxygen
• Eventually organisms developed a way to utilize
  oxygen
• Sex Who Needs It?
• We are a team Mitochondria
• Snowball Earth what survived and how?
• Cambrian "Explosion"

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Mass Extinctions
Causes ?

• Climate Change
• Disease
• Mountain-building
• Sea Level Change
• Competing Organisms
• Over-specialization
• Volcanism
• Meteor Impact

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Atmosphere

• Gasesous envelope that
• surrounds the Earth and
• constitutes the transition
• between its surface and
• the vacuum of space.
• The atmosphere consists of
• a mixture of gases composed primarily of
  nitrogen,
• oxygen, carbon dioxide, and water vapor.

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Atmosphere

• Troposphere - weather occurs
• Stratosphere - where the ozone layer is
  located

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Cryosphere

• The word "cryosphere
• originates from the greek word
• kryos, meaning frost or icy cold.
• The cryosphere is the portion of
• the Earth's surface where water
• is in a solid form, usually snow
• or ice. This includes sea ice,
• freshwater ice, snow, glaciers,
• and frozen ground (or permafrost).

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Hydrosphere

• The hydrosphere includes
• all water on Earth.
• Not a drop of liquid water
• can be found anywhere
• else in the solar system.
• Hydrologic Cycle

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Water

• Principal Agent in Modifying Earths Surface
• Medium for Storing and Distributing Global Heat
• The Universal Solvent
• Essential for Life
• Destructive to Rocks
• Lowers Melting Point of Rocks
• Reduces Strength of Rocks Under Pressure

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FRAMEWORK FOR EARTH SYSTEMS EDUCATION
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Understanding 1

• Earth is unique, a planet of rare beauty and
  great value.

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Understanding 2

• Human activities, collective and individual,
  conscious and inadvertent, affect planet Earth.

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Understanding 3

• The development of scientific thinking and
  technology increases our ability to understand
  and utilize Earth and space.

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Understanding 4

• The Earth system is composed of interacting
  subsystems of water, rock, ice, air, and life.

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Understanding 5

• Planet Earth is more than 4 billion years old and
  its subsystems are continually evolving.

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Understanding 6

• Earth is a small subsystem of a solar system
  within the vast and ancient universe.

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Understanding 7

• There are many people with careers that involve
  study of Earth's origin, processes, and
  evolution.