1. All About Plate Tectonics
   The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle
   http: //enchantedlearning.com/subjects/astronom...
   
   
2. How Plate Tectonics Works
   A spreading boundary is where the tectonic plates are separating. Some spreading boundaries are places where the crust is sinking downward as it is stretched thin
   
   http: //extremescience.com/PlateTectonicsmap.ht...
   
   
3. How Plates Move
   Learn about the ocean trenches and how volcanoes are formed.
   http: //volcano.und.nodak.edu/vwdocs/vwlessons/less...
   
   
4. Plate Tectonics & Heat Flow
   Information on Plate Tectonics & Heat Flow..
   http: //cotf.edu/ete/modules/volcanoes/vtectoni...