Ocean ridges can be found at divergent boundaries where two plates are moving away from each other. As the magma rises to fill the void, it cools into rock and forms new crust. The iron minerals in the rocks align with the earth’s magnetic field before the rock cools. This causes the rocks in these areas of seafloor spreading to have band-like patterns. The irons align differently each number of years in relation to the flipping of the earth’s magnetic field. This phenomenon has been used to determine the ages of these rock layers.
Volcanoes. It is an impressive sight: two sides of land so visibly ripped apart. The Mid-Atlantic Ridge that is to blame runs through the whole of Iceland
