1. Intrusive Volcanic Structures
   1. Batholith
      1. granite
      2. slowly cools
   2. Volcanoes
   3. Dike
      1. brings lava to surface
   4. Laccolith
      1. mound of lava
   5. Loppolith
      1. upsidedown laccolith
   6. Sill
2. What
   1. extrusive
   2. Volcanic
      1. lava
         1. low silica
            1. ropy
            2. runny
         2. cooling cinders
            1. clinkery
   3. Magma solidifies
      1. on earth's surface
      2. Near earth's surface
3. How
   1. flows through cracks
      1. cools
      2. contracts
         1. splits into columns
         2. basic lava
4. Giant's Causeway
   1. Antrim
      1. 65 million Ya
      2. 4000 SQ
      3. 800 M deep
   2. Extrusive Volcanic Structure
      1. 400 meters eroded
      2. heagonal columns
   3. Plateau
   4. formed
      1. plates pulled apart
         1. American
         2. European
      2. crust stretched
         1. cracks
         2. lava flowed
      3. Lava cooled quickly
      4. lasted 2 million Y
      5. eroded by sea
         1. edges
         2. cliffs
            1. undercut
            2. easily