Sea floor spreading was proposed by Harry Hess in the 1960s to explain the mid-ocean ridges. Sea floor spreading is when new sea floor is formed when magma is forced upward toward the surface at the mid-ocean ridge. The mid-ocean ridge is a large system of underwater mountains that have a deep crack, called a rift valley, running through their center. There is a great deal of volcanic activity that occurs at the mid-ocean ridge. The lava from the volcano hardens and forms new sea floor.
> Youngest rock~ near mid-ocean ridge
> Oldest rock~ farther away from the mid-ocean ridge
> Sound waves~ scientists were able to map the ocean floor and discovered a system of underwater mountain ranges
> Sea floor spreading helps explain how the continents drift
Scientists discovered that there is a permanent record of the Earth's magnetism in the rocks. This helped them discover that the magnetic poles reverse themselves from time to time. Studies show that over the past 3.5 million years, the magnetic poles have reversed themselves nine times. The pattern is identical on both sides of the mid-ocean ridge.
Scientists also discovered from drilling into the ocean floor, that the youngest rock is near the mid-ocean ridge and the older rock is farther away. This also helps prove that sea floor spreading actually does take place.
> Youngest rock~ near mid-ocean ridge
> Oldest rock~ farther away from the mid-ocean ridge
> Sound waves~ scientists were able to map the ocean floor and discovered a system of underwater mountain ranges
> Sea floor spreading helps explain how the continents drift
Scientists discovered that there is a permanent record of the Earth's magnetism in the rocks. This helped them discover that the magnetic poles reverse themselves from time to time. Studies show that over the past 3.5 million years, the magnetic poles have reversed themselves nine times. The pattern is identical on both sides of the mid-ocean ridge.
Scientists also discovered from drilling into the ocean floor, that the youngest rock is near the mid-ocean ridge and the older rock is farther away. This also helps prove that sea floor spreading actually does take place.