The geological action of the sea is what determines the coastal modeling through different movements of its waters:
- Sea currents. They are large masses of marine water that move in seas and oceans. Surface currents are caused by the action of the wind, and deep currents, by differences in density (temperature, salinity, etc.) between two bodies of water.
- Tides. They are ascents and descents of the sea level due to the gravitational pull of the Moon and, tolesser extent, the sun. Every day, any area of the Earth aligns itself twice with the Moon, producing two rises (high tide) and two decreases (low tide) in sea level.
Some particular cases of tides are spring tides, when the Sun and the Moon are aligned with the Earth, which occur twice a month, at full moon and new moon. On the other hand, neap tides occur when the Sun, the Earth and the Moon are arranged forming an angle of 90º, which also occurs twice a month, in the first quarter and the last quarter.
- Waves. Is heOscillatory movement of the particles on the surface of the sea that is produced by the action of the wind when brushing against the surface of the sea. The waves are the main component of the marine geological process, and it acts in several ways:
- Hitting the wave directly against the shore.
- Through the pressure exerted by the air that is between the cracks and fissures when compressed by the wave.
- Abrasion produced by the onslaught of waves loaded with rocky fragments.