Explain the evidence for seafloor spreading?

One piece of evidence for seafloor spreading is that with increased distance from the Mid Ocean Ridge (MOR), the age of rocks on the seafloor increases. This supports the concept that molten rock is ejected at the mid ocean ridge and cools, before being forced away from the MOR by the production of new material, resulting in the presence of younger material closer to the center. GPS can also be utilized to provide evidence of seafloor spreading. By utilizing GPS we can pinpoint the position of coastlines, and their relative distance from each other. Changes in their position can then be monitored, with a gradually widening ocean being evidence for seafloor spreading. Another, more complex, piece of evidence for seafloor spreading is the existence of magnetic stripes in the rock of the seafloor. The earth possesses magnetic poles (north and south poles) and the orientation of these poles reverses about every 200,000 years. Molten rock emerging from the MOR contains crystals of iron, these (due to iron being a magnetic metal) align in the direction of the earth's magnetic pole and then, as the molten rock cools, are preserved with this alignment as they form part of the sea floor. Analysis of the ocean floor shows a pattern of alternating stripes of magnetic alignment parallel to the MOR - in addition, this pattern is symmetrical across the center of the mid ocean ridge. This suggests the production of material at the MOR which was then forced to either side of the MOR as it cooled, each side preserving the magnetic alignment of the iron crystals within, alternating with the reversal of the poles.