Geology - The scientific study of the origin, history, and structure of the earth - The Science of the Earth - Different disiciplines of Geology - Historical - discovers the past - Physical - understanding

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Geology - The scientific study of the origin,
history, and structure of the earth - The
Science of the Earth -
Different disiciplines of Geology -
Historical - discovers the past -
Physical - understanding the processes
that operate on and inside Earth
Background Geology
Earths Internal Structure - Crust -
The outermost solid layer of Earth - Mantel
- the thick shell of dense, rocky matter
that surrounds the core - Core -
center densest part - largely metallic
iron - Atoms of Elements -Formed in
Solar Nebula - Minerals -General
chemicals compound formed by geological
process - Rocks - general
combination of minerals - Core Fe
Ni - Mantle O Si Mg -
Crust O Si
http//www.answers.com/Geology
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• plate tectonics
• theory that unifies many of the features and
  characteristics of continental drift and seafloor
  spreading into a coherent model and has
  revolutionized geologists' understanding of
  continents, ocean basins, mountains, and earth
  history.
• plate tectonics theory holds that the
  lithosphere, the hard outer layer of the earth,
  is divided into about 7 major plates and perhaps
  as many as 12 smaller plates, c.60 mi (100 km)
  thick, resting upon a lower soft layer called the
  asthenosphere. Because the sides of a plate are
  either being created or destroyed, its size and
  shape are continually changing. Such active plate
  tectonics make studying global tectonic history,
  especially for the ocean plates, difficult for
  times greater than 200 million years ago. The
  continents, which are c.25 mi (40 km) thick, are
  embedded in some of the plates, and hence move as
  the plates move about on the earth's surface.

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Types of Plate Boundaries
Compression - compacts a block of rock
squeezes it into less space - causes
shortening - reverse fault - convergent
boundary Tension ( also called dilation) - Pulls
a rock apart and inc. its length Causes
lengthening Normal fault Divergent
boundary Shear -Smears a block of rock and may
eventually tear it apart into blocks of rock
that slide past one of another along a
strike-slip fault Neither lengthening or
shortening Strike-slip fault Transform
boundary
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• Minerals
• Inorganic, naturally occurring substances that
  have a characteristic chemical compound,
• distinctive physical properties and
  crystalline structure
• Crystalline structure
• Is an orderly 3-D arrangement of atoms or
  molecules

• General. Mineral Properties
• Color
• Luster
• Is a des. Of how mineral surfaces reflect light
• Metallic
• Silvery, gold or brassy sheen
• Nonmetallic
• Luster unlike that of metal
• Streak
• Is color of substance after it has been ground to
  a fine powder

Metallic -Hematite
Hardness - Measure of resistance to scratching
mohs scale of hardness
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• Cleavage and Fracture
• Cleavage surfaces occur as sets of parallel
  surfaces of weak chemical bonding ( attraction)
  between repeating, parallel layers of atoms in a
  crystal
• Excellent cleavage
• Direction reflects light in one direction from a
  set of obvious, lg, flat and even surfaces
• Good cleavage
• Directions reflects light in one direction from
  a set of many small, obvious, flat, but uneven
  surfaces
• Poor Cleavage
• Direction reflects light in one direction from a
  set of flat, uneven surfaces that are
  inconspicuous compared to the fracture surfaces
• Most light is scattered randomly by the fractured
  surfaces
• Fractured surfaces of some irregular masses can
  be described as
• uneven
• splintery (like splintered wood)
• hackly ( jagged edges)
• conchoidal fractures
• smoothly curved fractures
• opal and pure quartz

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• Rocks

• Igneous Rocks
• are rocks that form when magma or lava cool to a
  solid form, either glass or masses of intergrown
  mineral crystals
• Common Igneous Rock Textures
• Glassy
• Completely lack grains
• Vesicular texture
• Have bubbles
• Have solutions cavities (cave-like spaces)
• Fractures
• Irregular spaces b/t poorly sorted grains of
  diverse size
• Randomly oriented small crystals fine- grained
  crystalline texture
• Grains gen. lt1mm and too small to identify
  without a hand lens
• Randomly oriented large crystals coarse-grained
  crystalline texture
• Grains gen. gt1mm lg enough to identify unaided

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• Sedimentary
• are rocks formed when fragments of plants,
  animals, or rocks are compressed together or
  otherwise hardened or they are masses of
  intergrown mineral crystals that precipitated
  from water( like the rock salt that remains when
  the ocean water is evaporated)
• Common Sedimentary Rock Textures
• Clastic texture contain clast (fragments) of
  minerals, other rocks, plants, or animals
• Detrital worn rock fragments
• Silty detrital (clastic) texture
• Sandy detrital (clastic) texture
• Layered crystalline texture
• Coarse-grained detrital (clastic) texture

Metamorphic

• Metamorphic Rocks
• are rocks changed from one form to another
  (transformed) by intense hear, intense pressure,
  or the action of hot fluids.
• Common Metamorphic Rock Textures (p. 69)
• Crystalline texture glittery when rotated in
  bright light
• Equigranular crystalline texture
• Equingranular all about the same size
• Folded texture
• Foliated small crystals and shiny reflection
• Foliated layered alighnemnt of flat-sided
  mineral grains so they are parallel to one
  another giving the appearance of folio-like
  (leaf-like)
• Foliated equigranular crystalline texture

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• Green house effect
• the property of the Earths atmosphere by which
  long-wavelength heat radiation from Earths
  surface is trapped or reflected back by the
  atmosphere

• Earths climate system consists of 4 interacting
  subsystems
• Atmosphere
• hydrosphere
• lithosphere
• biosphere
• solar energy drives the system
• some of the incoming radiation is reflected back
  into space from the clouds, atmospheric
  pollutants, ice , snow and other reflective
  surfaces

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• Tectonic movement affect
• surface relief
• which influences atmosphere circulation
• the geometry of continents and ocean basins
• which controls ocean circulations and location of
  ice sheets
• while volcanic and industrial gasses affect
  atmospheric composition
• The Carbon Cycle
• Natural fluxes of Carbon b/t the atmosphere,
  hydrosphere, biosphere, crust and mantel
• 1. carbon enters the atmosphere through
  volcanism, weathering and biological respiration
  and decay of organic matter in soils
• 2. photosynthesis incorporates carbon in the
  biosphere from which it can become part of the
  crust if buried w/accumulating sediment
• subduction liberates carbon from oceanic crust
  into the mantel
• anthropogenic activities release carbon to the
  atmosphere through fossil fuel-fuel use, combined
  w/deforestation and burning wood
• The Greenhouse Gases
• some of the short-wave (visible solar) radiation
  reaching Earth is absorbed by the land and
  oceans, while some reflects back
• Earth also radiates long-wave radiation
  (infrared) back to space.
• Greenhouse gases trap some of the outgoing
  long-radiation, causing the atmosphere to heat up
• W/inc. conc. Of these trace gases, the air temp
  of the lwr atmosphere rises.
• Historical Temperature Changes
• - Hemispheric and global temp changes since the
  mid-nineteenth century (w/both land and ocean
  data)