Geological Sciences 100

EARTH SYSTEM I:
GEOLOGICAL ENVIRONMENT

Lecture XXXVI. North American Geology

G) Phanerozoic History of North America (Cont.)

G) Phanerozoic History of North America (continued)
1. Incursions of marine waters
2. The Appalachian Mountains
3. The Rocky Mountains (Cont.)
  1. Cambrian to Devonian
  2. Devonian to Triassic
  3. Triassic through Early Cenozoic
  4. Mid-Tertiary (ca. 25 -30 Ma)
    
    Figure 36.1 Interaction between rise and trench leads to mutual annihiliation and the formation of the San Andreas Fault Zone and Coast Ranges, etc.
    - convergent transform margin
    - San Andreas fault zone
      
      Figure 36.2 Map of the California Coast Range and the Sierra Nevada (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).
  5. Present-day Cordillera
    
    Figure 36.3 Schematic cross section of the Cordilleran belt at about 40°N latitude showing possible diapir development of the Basin and Range Province.
    - Extensional tectonics
    - Basin & Range Province
      horsts and grabens
    - Hotspot activity
      Snake River & Yellowstone
      Rio Grand rift
      
      Figure 36.4 Present-day Cordilleran region (from The Changing Earth - Introduction to Geology (2nd ed.), by Mears, Jr., D. Van Nostrand Co., 1977).
4. Pleistocene (ca. 1 Ma) geology
  1. Nonglacial processes
    - weathering
    - erosion
    - transport
    - orogeny, etc.
  2. Glaciation
    
    Figure 36.5 Extent and location of Pleistocene glaciers in North America (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard, D. C. Heath and Co., 1973).
    - surficial topography
    - surficial deposits
    - rivers, streams, and lakes
      
      Figure 36.6 Extent of Pleistocene North American lakes, now greatly reduced or gone (from The Changing Earth - Introduction to Geology (2nd ed.), by Mears, Jr., D. Van Nostrand Co., 1977).
      
      Figure 36.7 Earlier episode in Great Lakes history when ice forced drainage into the Mississippi River (from The Changing Earth - Introduction to Geology (2nd ed.), by Mears, Jr., D. Van Nostrand Co., 1977).
      
      Figure 36.8 Later episode when ice retreat expanded lakes and opened a new outlet through the Hudson Valley of New York (from The Changing Earth - Introduction to Geology (2nd ed.), by Mears, Jr., D. Van Nostrand Co., 1977).
      
      Figure 36.9 Present Great Lakes with ice gone and drainage northeastward through the St. Lawrence River (from The Changing Earth - Introduction to Geology (2nd ed.), by Mears, Jr., D. Van Nostrand Co., 1977).
    - Ohio's drainage divide ==> controlled by isostatic rebound due to retreat of glaciers
      
      Figure 36.10 Ohio drainage basins and divide.