Geologic Development of California

Major Mountains of California

• Sierra-Nevada - classic example of a fault-block mountain range.
  • Mt. Whitney - 14,495 ' (tallest in continental U.S.)
• Coast Range - example of mélange; sedimentary and metamorphic
  • Mt. Linn - (8,000')
• Klamath & Siskiyou Mountains - also known as "Klamath Knot"
  • Trinity Alps and Mt. Thompson - (9002')
• Cascades - active volcanic range (igneous extrusive)
  • Mt. Shasta (14,152'), Castle Crags & Mt. Lassen (10,457)
• Basin & Range - back side of Sierra-Nevada
  • White Mountain Peak (14.242') above Death Valley (-282)
• Transverse and Peninsular Ranges - "it their fault" southern California
  • Mt. San Jacinto (10,804') and Channel Islands (2,125')

Plate Tectonics - General Concepts

• Evidence
  • geothermal heat, bulges, volcanoes, faults, and earthquakes
  • different north and south coastlines
    
    
• Major Plates: oceanic and continental
  • Pacific
  • North American
  • Gorda and Juan De Fuca
    
    
• Sea-floor spreading
  
  
• Subduction
  
  
• pair belts of mélange & magmatism
  

Geologic History of California - Movement, Mountain Building & Deformation

1) Subduction - Pacific Plate jammed beneath North American Plate (200 million)

• scraping / jamming of sea floor sediments into Sierran trench
  • color images of sea floor (north and south)
• crumpling, dipping, folding and faulting
  
  

2) California Mountains emerge (150 million)

• accretion - slices of old sea floor added to edge of continent
• Sierran Trench jump 60 miles west (130 million)
  • Great Central valley eventually emerges
    
    

3) Plate movement shifts (30 million)

• Subduction ceases
  
  • Franciscan uplift becomes western Coast Range
  • long chains of volcanoes rise through batholith
    • granite and exfoliated domes
      
      
• Lateral movement begins - San Andreas fault
  
• System of parallel faults
• 300-350 miles of movement
• Tranverse Range created & compressed
  
  
• New interior batholith and rising magma
  • Modoc Plateau rises with active volcanoes
  • Basin & Range undergoes stretching and block faulting
  • Sierra Nevada Mountain Range tilts up to the east
    • fault-block mountain range
  
  

- Geology Worksheets

- Video to explain Plate Tectonics, Subduction, etc. (Earth Rocks, ESCI 119/120)

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