Rocks

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Rocks Geologic Time

• Introduction to Rocks Minerals
• Igneous Rocks Bowens Reaction Series
• Metamorphic Rocks
• Sedimentary Rocks
• The rock record Geologic time

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Minerals

• Naturally Occurring
• Inorganic
• Solid
• Crystalline Structure
• Definite Chemistry
• Distinguishing are chemistry and structure

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Why Should you Care?

• It is impossible to make it through a single day
  without the use of a Geologists work.
• Everything (including you!) is made up of
  minerals or elements taken from the Earth.
• You may not like geology or rocks or minerals,
  but you cannot escape them!

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Which of the Following are Minerals?

• Coal?
• Salt?
• Ice?

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Coal

• It is naturally occurring
• It is solid
• It has a definite chemistry
• It has a crystalline structure
• It is NOT inorganic
• Therefore COAL is NOT a mineral

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Salt?

• It is naturally occurring
• It is solid
• It has a definite chemistry
• It has a crystalline structure
• It is inorganic
• Therefore SALT IS a mineral

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Ice?

• It is naturally occurring
• It is solid
• It has a definite chemistry
• It has a crystalline structure
• It is inorganic
• Therefore ICE IS a mineral

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Most Common Elements in the Crust of the Earth

• Oxygen (O2-)
• Silicon (Si4)
• Aluminum (Al2)
• Iron (Fe2,3)
• Calcium (Ca2)
• Sodium (Na)
• Potassium (K)
• Magnesium (Mg2)

Silica Tetrahedra
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Minerals make up Rocks

• Rocks are simply aggregates of one or more
  minerals.
• Three types of Rocks
• Igneous Born of Fire
• Metamorphic Born of Change
• Sedimentary Born of Dirt

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Igneous Rocks

• Formed when minerals and other rocks melt
• Are classified according to their chemistry and
  texture
• Bowens Reaction Series Explains all there is to
  know

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Texture of Igneous Rocks

• Texture describes how the minerals fit together
  in a rock and their size
• Fine-grained are usually volcanic rocks
• Coarse grained are commonly plutonic rocks.

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Definitions

• Plutonic Intrusive (magma stays underground)
• Volcanic Extrusive (magma flows to the surface)
• Lava Magma that has reached the surface.

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Geothermal Gradient

• Why do rocks melt?
• Because the earth is hot inside!
• The change in temperature with increasing depth
  is called the Geothermal gradient.

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What Happens When Rocks Melt?

• They expand which causes.
• The density to decrease (because you have the
  same amount of rock in a larger volume) which
  causes..
• The melted rock to rise toward the surface!

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Bowens Reaction Series (Chemistry of Igneous
Rocks
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Additional Notes on Bowens

• As SiO2 increases density decreases.
• As SiO2 increases melting temperature decreases.
• As SiO2 increases crystallization temperature
  decreases.
• As SiO2 increases viscosity increases.
• As SiO2 increases explosive potential increases.

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Trivia Question

• What type of magma comes from the volcano at Mt.
  St. Helens?
• What type of magma comes from the volcanoes in
  Hawaii?

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More Interesting Trivia

• Why are continents, continents?
• Why are oceans, oceans?
• Answer
• Continental Crust Thick and Light (2.7)
• Oceanic Crust Thin and Heavy (2.9)

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Metamorphic Rocks

• Metamorphic rocks change shape or texture due to
• Pressure
• Temperature
• Chemical Conditions

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Metamorphic Rocks

• Deformation of rock on a large scale is called
  REGIONAL METAMORPHISM
• Smaller scale metamorphism due to hot fluids is
  called HYDROTHERMAL METAMORPHISM
• Smaller scale metamorphism due to hot rock
  encountering cold rock is called CONTACT
  METAMORPHISM

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Sedimentary Rocks

• Born of Dirt (sediment)
• Other rocks break down and are transported,
  buried and cemented.
• Chemical and Clastic Sedimentary Rock
• Rocks are layered.

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Chemical Sedimentary Rocks
Halite (Rock Salt) Precipitated from
Seawater Limestone CaCO3 Precipitated from
Seawater Dolomite CaMg(CO3)2 Altered limestone
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Biogenic Sedimentary Rocks
Coquina Shell fragments w/calcite and phosphate
cement Castillo de San Marcos- Built of Coquina
Washington Oaks Gardens Coquina
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Clastic Sedimentary Rocks
Clastic Sedimentary Rocks include Sandstone,
Shales, Mudstones, Conglomerates.