4. Compare and contrast the rate of sea floor spreading along the Mid-Atlantic Ridge and East Pacific Rise.

The Mid-Atlantic Ridge runs down the center of the Atlantic Ocean. ... The rift valley is 1 to 3 km deep, about the depth and width of the Grand Canyon. In contrast, the East Pacific Rise spreads fast at rates of 6 to 16 cm per year (more than 20 cm per year in the past).

igneous rocks which formed by the crystallization of magma at the surface of the earth called extrusive rocks. they are characterized by fine-grained textures because the rapid cooling at or near the surface did not provide enough time for large crystals to grow.