A cliff is a mass of rock that rises very high and is almost vertical, or straight up-and-down. Cliffs are very common landscape features. They can form near the ocean (sea cliffs), high in mountains, or as the walls of canyons and valleys
<em>A cliff is a steep and often sheer rock face. If you stand on the edge of a cliff and peer over, you'll be able to see the waves crashing on the rocks below.</em>
