Coastal Processes, Hazards, and Society

Environments of Coastal Zones


Environments of Coastal Zones

In what sort of tectonic setting would you expect rocky coasts most often? What is the role of different rock types in how erosion may take place along an uplifted, high wave energy rocky environment?

Rocky Coasts

Some estimates suggest that nearly 75% of the world’s shorelines are considered rocky coasts, meaning that the shoreline consists of erosionally resistant cohesive bedrock or sediment that has been recently cemented together to form a cohesive unit. Most often, rocky coasts are in areas of high wave energy and are erosional with only localized areas where sediment might accumulate, such as small beaches between rocky headlands. They exist across a wide range of geologic settings, including very mountainous regions, areas that have been or are covered with glacial ice, or along volcanoes that are located in the open oceans. Although rocky coastlines may be present on passive, trailing tectonic margins, they are most frequently located along collisional tectonic margins.

Very flat rocks - see caption for more.
Rocky shoreline at Bheemunipatnam, India.
Credit: Adityamadhav83, CC0, via Wikimedia Commons
Many boulders in the water - see caption for more.
Rocky shoreline along the coast of Oregon, United States.
Credit: By Jsayre64 at Wikipedia CC-BY-SA-3.0 or GFDL, via Wikimedia Commons
Tall rocky cliffs - see caption for more.
Rocky cliff line along the coast of Ireland.
Protruding headlands undergoing erosion - see caption for more.
Rocky coast along Sozopol, Bulgaria shows several protruding headlands that are undergoing erosion as indicated by the fragments of the headlands in the water. Notice the deformed folded rock in the foreground indicated by the arrow and how this deformed unit of rocks is more indented and thus eroding more quickly than the surrounding rock. Also, note the isolated pocket beach in the background that is also denoted with an arrow.
Credit: By Evgeni Dinev from Burgas, Bulgaria (Flickr) [CC-BY-2.0], via Wikimedia Commons