what do you think the origin of the broad, flat surface is above the coastal cliffs shown below?

At the shoreline the currents can be deflected longshore and water may return seaward as a rip current. In breaking, waves transform their potential energy to kinetic energy, which is initially manifest as the broken wave of translation, or wave bore, which moves shoreward as broken white water. They can break as a spilling breaker on low gradient slopes, a plunging wave on moderate gradients, or a surging wave on steep slopes. Waves break when the water depth is approximately 1.5 times the wave height. The surf zone is the most dynamic part of the beach and extends from the breaker zone to the shore. For this reason waves slow down as they move towards the shore, with a 10 sec wave traveling at 56 km/hr (35 mph) in deep water slowed to 7 km/hr (4 mph) in 5 m water depth. When waves enter shallow water their velocity is controlled by the water depth (d) such that C=√gd where g is the gravitational constant.

The longer the period the longer and faster the waves, as wave length L=1.56 T, and wave velocity C = 1.56 T 2. Waves are defined by their height (H) (trough to crest), length (L) (crest to crest) and period (T) (time between successive crests). Swell waves can theoretically travel around the world with minimal loss of energy, while in reality they eventually break on some distant shore.Waves are a form of potential energy that can be transported across hundreds to thousands of kilometers of ocean to be released as kinetic energy when they shoal and break. Once the wind stops blowing, and/or the waves leave the area of generation, they quickly transform into swell - lower, longer, faster and uniform in direction. When waves are being generated they are called a sea and consist of short, steep, high, slower waves, which tend to topple over and break, and have a broad spectrum of direction.

What do you think the origin of the broad, flat surface is above the coastal cliffs shown below?