The Pacific coast of North America is strikingly different from the Atlantic coast. Construction of breakwaters or seawalls parallel to the shore to reduce the impact of waves. Emergent and Submergent Coasts Emergent coasts Develop where coast has been uplifted or as a result of a drop in sea level. Areas that were once buried beneath great ice sheets. Characterized by extensive wave-cut cliffs and platforms.
Submergent coasts Develop where rising sea level has submerged stable coastal regions.
Characterized by drowned river mouths called estuaries. Periodic changes in the level of the ocean surface caused by the gravitational attraction of the moon and, to a lesser extent, the sun. The centrifugal force is everywhere the same on the earth, but the gravitational force is less on the side opposite the moon and greater on the side toward the moon, thus producing two bulges. Similarly for the sun. The effects of the moon and sun are additive.