Different types of movement cause different types of land formations. The spreading plate boundaries are mostly found on the ocean floor. Fresh lava pushes upward and forms new crust which pushes the plates apart and builds a chain of volcanoes called an oceanic ridge. The ridges connect in a continuous mountain chain that runs throughout the earth's oceans. This mountain chain is 40,000 miles long and contains some of the world's tallest peaks. Most of the mountains are hidden beneath the water, but some emerge from the waves to form islands. The ridge encircles the earth much like the seams of a baseball.