Earth

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Earths Internal Structure, Rock Cycle, and
Geologic Time January 16, 2014
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Earths Internal Structure, Rock Cycle, and
Geologic Time

• Earths inner structure
• Rocks and minerals in the Earths crust
• Geologic time
• Basic geomorphology of continents and ocean basins

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Earths Interior
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Earths Interior
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(No Transcript)
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Lithosphere
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The Geologic Cycle

• The vast give-and-take at the Earth-atmosphere-oce
  an interface or cycling within the lithosphere
• Fueled by the sun and Earths internal heat
• Geologic Cycle

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The Geologic Cycle
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The Rock Cycle

• Minerals vs. Rocks
• Minerals
• Naturally-occurring, inorganic solid with a
  definite chemical composition
• Rocks
• Made up of one or more minerals

Granite rock make up of variety minerals.
http//geomaps.wr.usgs.gov/parks/rxmin/rock.html
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Igneous Rock

• Formed from cooled magma liquid rock from
  asthenosphere
• Extrusive igneous rock
• Intrusive igneous rock

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Igneous Rocks
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Extrusive Igneous Rock
Basalt - fine-grained, dark-colored extrusive
igneous rock
Rhyolite - fine-grained, dark-colored extrusive
igneous rock
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Intrusive Igneous Rocks
Diorite coarse-grained, intrusive igneous rock
Gabbro coarse-grained, intrusive igneous rock
Granite coarse-grained, intrusive igneous rock
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Sedimentary Rock

• Vast amts of formerly loose minerals (sediment)
  deposited in layers
• Sediments cement to each other in process called
  lithification
• 3 Types

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Clastic Sedimentary Rock Examples
Siltstone
Sandstone
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Chemical Sedimentary Rock Formation
Andros Island, Bahamas
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Chemical Sedimentary Rock Examples
Limestone - can also form chemically from the
precipitation of calcium carbonate from lake or
ocean water
Rock Salt - forms from the evaporation of ocean
or saline lake waters.
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Organic Sedimentary Rocks

• Coal from plant and organic matter deposited in
  cool wetlands, forming peat over time overlying
  layers of sediment compress heat peat into coal
• Overcooked deposits become petroleum
• Natural gas from microscopic plants at surface
  of sea water decompose to gas

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Metamorphic Rock Types

• Parent rock can be sedimentary, igneous or
  metamorphic rocks

Parent Rock (rock type) Metamorphic Rock Metamorphic Features
Sandstone (sedimentary rock) Quartzite Quartz with silica cement
Limestone (sedimentary rock) Marble Fizzes with dilute HCl acid
Shale (sedimentary rock) Slate Sheet-like
Slate (metamorphic rock) Schist Displays flat shiny surfaces
Granite (igneous rock) Gneiss Alternating dark and light layers
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Metamorphic Rock Examples
Schist
Marble
Slate
Quartzite
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The Rock Cycle
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The Rock Cycle
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Geologic Time

• Earths history (4.5 B years) divided into
• Eons
• Eras
• Periods
• Epochs
• Radiometric Dating compare amt of radio-active
  isotope to amt of decayed end product in a rock
  to estimate its age

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Geologic Time
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Geomorphology of Continents and Ocean Basins

• Geomorphology study of formation, shape,
  distribution, evolution of landforms on Earth
• Landform a distinct geographic feature such as
  a mountain, river valley, coastline, or sand dune
• Continents consist of 3 basic geomorphic regions
  Alpine Chains, Continental Shelves, Continental
  Shields

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Continental Shelf
Earths land area increases dramatically (from
29 to 35 of Earths surface) if sea level falls
as in a previous glaciation (1.6 my ago) because
of the relatively shallow continental shelf.
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Continental Shields

• Geologically inactive regions with low relief
  made of old, stable, igneous or metamorphic rock

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Alpine Chains

• Belts of active mountain building due to volcanic
  or tectonic processes