Leonard's crossword

12345678
Across
  1. 1. A deep undersea valley where crust sinks towards the mantle.
  2. 3. The process by which crust sinks back into the mantle at a colliding plate boundary
  3. 5. An original version or blueprint.
  4. 6. A force that sends an object forward.
  5. 7. A device that reflects sound waves off underwater objects and records the echoes
  6. 8. The way a person behaves.
Down
  1. 1. Apartment housing that is overcrowded and not well taken care of
  2. 2. An undersea chain of mountains that is part of a long system of underwater mountains
  3. 3. spreading The process by which molten material adds new crust below Earth's bodies of water
  4. 4. An aggressive young man that is usually a trouble maker.