How do ocean waves affect your coastlines?

Answer 1

1. Ocean wave effects on Coastlines depend greatly on the material composition of the land mass within the coastline.

2. Ocean wave effects on coastlines in this answer is preferred to be separated from the effects from tides, currents and ocean flooding.

3. Land moving effects such as advancing river deltas, and other movements of such as plat-technonics are separate.

Two opposite tendencies of wave effect exist for coastlines of sand versus coastlines of rock. A coastline of rock will erode in a chaotic manner dictated by the chaotic composition of the rock's consistent or inconsistent composition of weak rock, and strong rock. The coastline erodes according to that pattern due to wave action almost indiscriminately with one exception concerning wave focusing.

Wave focusing occurs when the underwater contours of depth (bathymetrics) become shallow or deeper. Bathymetry effects on waves are analogous to glass lenses effect on light. In the same way light travels slower through denser material like glass, ocean waves travel slower in shallow water than deep water. These effects focus waves energy away from bays and towards points. In this way waves tend toward flattening a coastline by picking up sand near a point and depositing it in a bay. So why aren't all coastlines flat? because of points 1, 2, 3 and the previous paragraph.