Final answer:
Oceanographers discovered the major ocean floor feature called mid-ocean ridges after World War II. These ridges are formed by divergent plate boundaries and are characterized by volcanic activity and the formation of new crust.
Step-by-step explanation:
After World War II, oceanographers discovered the major ocean floor feature known as mid-ocean ridges.
These ridges are underwater mountain ranges and rift systems formed by divergent plate boundaries in the ocean. They are characterized by volcanic activity and the formation of new crust as molten rock rises to fill the space between the separating plates.
The Mid-Atlantic Ridge is one example of a mid-ocean ridge.