Drill cores from the ocean floor were dated and found to be very young compared to the age of the earth. This means the crust had to be formed recently, which can be explained by creation of crust at a spreading center.
The theory of seafloor spreading states that seafloor lithosphere is not stationary, on the contrary, it is constantly renewing at mid-ocean ridges. The research from the Glomar Challenger, that use a scientific drilling vessel, helped to support this theory by taking rock samples from the Mid-ocean ridge. After analyzing the rock samples it was revealed that the farther from the mid-ocean ridge, the older the rock was.
