if you payed attention, you'll know...

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Across
  1. 3. proposed the continental drift theory
  2. 4. a tectonic boundary where two plates are moving towards each other
  3. 6. a moving or extending in different directions
Down
  1. 1. convection heat transfer
  2. 2. most dense layer made of iron and nickel
  3. 5. upper mantle or the rigid outer part of earth