East Pacific Rise Part of the nearly uninterrupted mountain chain that circles the earth on the seafloor, the East Pacific Rise (EPR) extends from about the Gulf of California to 55° S in the eastern half of the Pacific Ocean. The EPR towers above the surrounding seafloor, or abyssal plain, because heat from deep within the earth's crust expands the rocks. The Rise contains the youngest real estate on earth, created as the earth is pulled part at about 10-20 cm/year, and lava wells up from under the crust. The lava, which is frozen on contact with seawater, forms glassy basalts that will dull with age.