Figure 35.1 Principal structural elements of North America in Cambrian and later time (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).

• lithofacies map ==> past depositional environments

• isopach map ====> rock thicknesses

  
  
  Figure 35.2 Isopach and lithofacies map of the Cambrian System in North America. Cambrian rocks are probably more extensive than shown, but information about them is sketchy in northern parts of the continent, in the Western Cordillera, and beneath the coastal plains. In areas covered by the limestone pattern, Cambrian rocks are mostly limestone and shale; the shale pattern indicates mostly shale and sandstone; the dotted pattern, mostly sandstone (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).
  
  
  

1. Incursions of marine waters

   
   
   Figure 35.3 Chart summarizing chief aspects of the geologic history of North America since the Precambrian. Shaded areas show extent of marine waters on the continent, as indicated in scale across top. Wavy lines are regional unconformities. Orogenies in the continent's three major mobile belts are shown at right (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).
   
   
   

2. The Appalachian Mountains
   • Taconic orogeny (Ordovician - Silurian) ==> B

   • Arcadian orogeny (Devonian) ==> C

   • Allegheny and Ouachita orogenies (Carboniferous - Permian) ==> D

   • Palisades disturbance (Triassic) ==> E

     
     
     Figure 35.4 These simplified diagrams depict the development of the southern Appalachians as the ancient North Atlantic was closed during the formation of Pangea. Three separate stages of mountain building activity spanned more than 300 million years (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).
     
     
     

3. The Rocky Mountains

   
   
   Figure 35.5 The United States is part of a rather symmetrical continent having a stable interior flanked by highlands. The Atlantic coastal plain may represent a geosyncline (from The Changing Earth - Introduction to Geology (2nd ed.), by Mears, Jr., D. Van Nostrand Co., 1977).
   
   
   
   
   Figure 35.6 Chart summarizing chief aspects of the geologic history of North America since the Precambrian. Shaded areas show extent of marine waters on the continent, as indicated in scale across top. Wavy lines are regional unconformities. Orogenies in the continent's three major mobile belts are shown at right (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).
   
   
   

   1. Cambrian to Devonian (ca. 600 - 405 Ma)
      • passive margin miogeosyncline

      • accretion of oceanic & island arc assemblages

        
        
        Figure 35.7 The Cordilleran region from early Paleozoic to Devonian time. The Cordilleran geosyncline with miogeosynclinal and eugeosynclinal sites of deposition lay west of the continental platform (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).
        
        
        

   2. Devonian to Triassic (ca. 405 - 230 Ma)
      • active margin developing

      • Antler orogeny

      • Sonoma orogeny

        
        
        Figure 35.8 The Cordilleran region from Devonian to early Triassic time. After the development of the Antler and Sonoma belt, the site of the Paleozoic Cordilleran geosyncline was divided into an eastern geosynclinal belt along the Pacific border (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).
        
        
        

   3. Triassic through Early Cenozoic (ca. 220 - 60 Ma)
      • Andean-type margin

      • Nevadan orogeny

      • Sevier orogeny

      • Laramide orogeny

        
        
        Figure 35.9 The Cordilleran region in Mesozoic time. By latest Cretaceous time, Nevadan Sevier and Laramide orogenies had created a wide mountainous belt across the Cordillera (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).
        
        
        
        
        Figure 35.10 Mesozoic plate relations along the Cordilleran margin. Prior to the development of the San Andreas fault, plates of the Pacific Ocean were probably descending beneath the North American plate and creating a subduction zone like the present one along the west coast of South America (from Geology - An Introduction (2nd ed.), by Bates, Sweet, & Utgard,   D. C. Heath and Co., 1973).