<Ol> <Li> the stripes are symmetrical around the crests of the mid-ocean ridges; at or near the crest of the ridge, the rocks are very young, and they become progressively older away from the ridge crest; </Li> <Li> the youngest rocks at the ridge crest always have present - day (normal) polarity; </Li> <Li> stripes of rock parallel to the ridge crest alternate in magnetic polarity (normal - reversed - normal, etc .), suggesting that they were formed during different epochs documenting the (already known from independent studies) normal and reversal episodes of the Earth's magnetic field . </Li> </Ol> <Li> the stripes are symmetrical around the crests of the mid-ocean ridges; at or near the crest of the ridge, the rocks are very young, and they become progressively older away from the ridge crest; </Li> <Li> the youngest rocks at the ridge crest always have present - day (normal) polarity; </Li> <Li> stripes of rock parallel to the ridge crest alternate in magnetic polarity (normal - reversed - normal, etc .), suggesting that they were formed during different epochs documenting the (already known from independent studies) normal and reversal episodes of the Earth's magnetic field . </Li>

What is the activity of the earth moving plates called