1. 
   hadal zone
   (from the article `marine ecosystem`) ...continental slope and rise. The abyssal zone (between 4,000 and 6,000 metres) represents a substantial portion of the oceans. The deepest region ...
   Found op http://www.britannica.com/eb/a-z/h/2
   
   
2. 
   Hadal zone
   The hadal zone (named after the Greek god, Hades, god of the Underworld), also known as the hadopelagic zone and trench zone, is the delineation for the deepest trenches in the ocean. This zone is found from a depth of around {convert|6000|m|ft} to the bottom of the ocean. ==Conditions== In 1960, J...
   Found op http://en.wikipedia.org/wiki/Hadal_zone
   
   

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