Figure 9.1 Relationship of active volcanoes to major plate boundaries.




Figure 9.2 Three zones of volcanism. Two of these zones are plate boundaries, and the third includes areas within the plates themselves (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).

Figure 9.3 Cross sectional view illustrating the basic intrusive igneous structures (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).

• Plutonic (intrusive) Rocks
  1. Shape (tabular, massive)

  2. Orientation to country (host) rock (discordant, concordant)

  3. Types of plutons
     • batholiths

       
       
       Figure 9.4 Batholiths in the shield of Western Australia from Landsat.
       
       
       

     • stocks

     • laccoliths

     • dikes (or dykes)

       
       
       Figure 9.5 Dike through Mt. Moran (Grand Tetons Nat'l Park, WY).
       
       
       
       
       Figure 9.6 Close-up of Mt. Moran Dike in Figure 9.5.
       
       
       

     • sills

     • volcanic necks & feeders

     
     
     
     Figure 9.7 Flood basalts. Magma erupts from fissure cut through earlier crystallized flows to produce a thick accumulation of basaltic rock (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).
     
     
     
     
     Figure 9.8 Map of Columbia Plateau, showing areas built by fissure eruptions (from Physical Geology (3rd ed.), by Leet & Judson, Prentice-Hall Inc., 1965).
     
     
     
     
     Figure 9.9 Lava flows of Columbia Plateau (Palouse River, WA).
     
     
     
     
     Figure 9.10 Major plateau basalts.
     
     
     
• Volcanic (extrusive) Rocks