1. Magnetic Striping: The ocean floor exhibits a pattern of alternating magnetic stripes, with bands of rock exhibiting normal polarity (aligned with the Earth's current magnetic field) and reversed polarity (aligned opposite to the current magnetic field). These stripes are symmetrical about mid-ocean ridges, where new oceanic crust is formed. This pattern can be explained by the process of seafloor spreading. As molten rock rises at the mid-ocean ridge and cools, it records the Earth's magnetic field at the time. Since the Earth's magnetic field flips periodically, new crust forms with alternating magnetic polarities. This symmetrical pattern provides strong evidence that the seafloor is spreading away from the mid-ocean ridges.
2. Age of Ocean Floor Sediments: Ocean floor sediments are much younger than the continents, and their age increases as you move away from mid-ocean ridges. This is consistent with the seafloor spreading hypothesis. As new ocean floor is formed at the ridges, older crust moves away from the ridge, making the sediments further away from the ridge older. Additionally, the thickness of sediment layers increases as you move away from the ridge, indicating that sediment has been accumulating over a longer period of time.
