Final sprint to finish line.

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Final sprint to finish line.

• Exam IV scheduled for Wednesday, Dec. 19,
  1000-1150am
• Review session??
• See me for grades later Wednesday

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Ch. 19 Review

• Modern ice age
• Human evolution

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Reconstruction ofAustralopithecus
Shoulder joint typical of arborescent apes, long
arms, strong wrists, long curved fingers
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African emmigrant
1st widespread hominid
Eurasian hominid
increase in brain capacity
climate change
bipedalism
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Todays outline Neogene tectonics

• Destruction of the Tethyan seaway
• Development of the American west
• Rejuvenation of the Appalachians

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Destruction of the Tethyan Seaway

• In Neogene time, Indian Subcontinent and several
  smaller continental fragments of Gondwanaland
  collided with Eurasia
• Result was Himalaya Mountains, mountains of the
  Near East, and Alps
• Today, only the Mediterranean Sea, Black Sea,
  Caspian Sea, and Aral Sea are vestiges of the
  former Tethyan Seaway

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Final driftof IndianSubcontinent
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Closure ofTethys Seaway
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Modern Geology of theAmerican West

• All modern physiographic provinces of the
  American west were formed during Neogene time
• Rocky Mountains
• Colorado Plateau
• Basin and Range
• Columbia Plateau/Snake River Plain
• Cascades
• Sierra Nevada
• Coast ranges

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Western physiographic provinces
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Western physiographic provinces

• Rocky Mountains are a very high (14,000 ft)
  basement uplift
• Colorado Plateau is a high plain (elevation
  5,000 ft) of highly dissected, but nearly flat
  strata
• Grand Canyon, Green River Canyon
• Basin and Range is an area of semi-parallel
  mountains and valleys formed by block faulting

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Green RiverCanyon(near Moab, Utah)
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Basin and Range
Extensional forces (stretching)
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Western physiographic provinces

• Columbia Plateau and Snake River Plain is a
  broad, flat area of extrusive volcanic rocks
  (basalt flows)
• Cascades are volcanic mountains (e.g., Mount St.
  Helens)
• Sierra Nevada is a granitic uplift
• Coast Ranges are faulted and folded mountains

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Sierra Nevada
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Eastern face of Sierra Nevada
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Origin of western tectonism

• Coast Ranges, Cascades, and Columbia River
  Plateau/Snake River Plain are directly related to
  subduction along western continental margin
• Uplift of Colorado Plateau and Rocky Mountains
  may be partly isostatic, but mostly related to
  swelling within the mantle
• Sierra Nevada is a basement uplift associated
  with plate margin tectonics

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Origin of western tectonism

• Origin of Basin and Range is problematic, but
  possibly related to western margin tectonics and
  origin of San Andreas fault
• Complex interaction where a spreading ridge
  becomes part of a subduction zone
• Transform fault (San Andreas)
• Extensional thinning of the crust (Basin and
  Range)

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San Andreas Fault and crustal thinning (Basin and
Range)
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Rejuvenation of the Appalachians

• Last episode of deformation in Appalachians was
  Alleghenian Orogeny
• Pennsylvanian time
• Appalachians were completely leveled by erosion
  during Mesozoic time
• Modern topography developed in response to
  Neogene isostatic uplift
• Mild, vertical elevation without deformation

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Rejuvenation of the Appalachians
Cretaceous
Holocene
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Major Events in Earths History

• Origin of the Earth
• Formation of continents
• Origin of life (simple cells)
• Origin of multicellular life
• Invasion of land by plants and animals
• Formation of major mountain chains
• Assembly and break-up of supercontinent Pangaea
• Five great mass extinctions
• Age of dinosaurs
• Origin of mankind

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Key Messages

• Close linkage between biologic events and
  geologic events
• Need to look at Earths history in order to
  understand Earth today
• Change is normal

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Earth in the year 50,002,001 A.D.