A. Earth's Interior Structure (fig 13-2)

1. lithosphere
   1. "rock sphere"
   2. outermost layer
   3. hard, rocky, rigid
   4. makes the 'plates' of plate tectonics
   5. about 100km thick
   6. two types of lithosphere:
   • oceanic lithosphere
     • thinner
     • heavier
     • uniform (basalt) composition
     • younger
   • continental lithosphere
     • thicker
     • less dense (lightweight)
     • diverse rock compositions
     • may be quite old (up to 4ba)
2. asthenosphere
   1. "without strength"
   2. underneath lithosphere
   3. hot, soft, mushy
   4. convection causes motion

B.  Plate Boundaries (fig. 14.7, 14-10, 14-11)

1. divergent boundaries - mid-ocean ridges, basalt volcs; create ocean crust
2. convergent boundaries -
   1. at least one ocean plate: subduction zones - explosive volcs.; destroy ocean crust
   2. two continents: continental collision, huge mountains
3. transform boundaries

C. Divergent Boundaries (fig. 14-8, 14-2, 14-3)

1. motion: away from each other
2. creates ocean crust
3. gentle lava volcanoes
4. small shallow earthquakes
5. mid-ocean ridge
6. Iceland, Mid-Atlantic Ridge

D. Convergent Boundaries (fig.14-14)

1. subduction zone
   1. motion - toward each other, ocean crust goes down under other plate
   2. destroys ocean crust
   3. explosive, deadly volcanoes
   4. huge, deep earthquakes
   5. trench and volcanic arc
   6. Cascades, Japan, Andes, Philippines, Aleutians
2. continental collision
   1. motion - toward each other
   2. no effect on ocean crust
   3. no volcanoes
   4. variable earthquakes
   5. huge mountains
   6. Himalayas, Alps, Appalachians

E. Transform (fig. 14-16)

1. side-by-side sliding motion
2. no effect on ocean crust
3. no volcanoes
4. variable earthquakes
5. subtle landforms
6. San Andreas