Indiana University
Indiana University: Evolution of Continents and Oceans
A course lecture on how the Earth's geological features have evolved through the movements of tectonic plates. Explains the different types of plate boundaries and how they manifest in geological formations. Also describes the structure...
National Geographic
National Geographic: Encyclopedia: Ocean Trench
Comprehensive information about deep-ocean trenches. Includes maps, a video [1:29], and a vocabulary list.
Woods Hole Oceanographic Institution
Woods Hole Oceanographic Institution: Trenches
Explains what ocean trenches are and why they are important. Includes links to videos, additional articles, and information about some deep-ocean submersibles.
Encyclopedia Britannica
Encyclopedia Britannica: Geology: Deep Sea Trench
Detailed information about oceanic trenches, their structure, and how they are formed. Discusses the twenty trenches that exist around the world. Includes several labeled illustrations.
Other
San Andreas fault.org: Tectonics
Provides a good overview of plate tectonics with embedded links to related information.