Lopsided Cliffs that Reduce Coastal Erosion

 Cliff Profiles in Montenegro

Although I am not naturally prepared for attacking the Mediterranean mid-day sun (blonde hair and near-transparent skin), like all true Brits finding the perfect beach for sun-worshipping is the benchmark of any half decent holiday.

The Dream Beach (Photo: Natasha Driscoll)

In the midst of this challenge, we saw the dream beach from our hiking path between Petrovac (a tourist bay which has fully utilised its beach) and Bausunde (a huge derelict hotel complex which was evidently stopped due to limited funds).

The derelict hotel complex of Bausunde. (Photo: Natasha Driscoll)

It became the mission of my fellow holidayers to reach said dream beach by whatever means possible, resulting in us scaling down the side of a cliff via some rather precarious steps before reaching a possible path. The path, unfortunately, did not reach the beach and we determined that there was no possible route via land (and were not well equipt enough to travel with all our belongings via swimming). Hence we retired from the search of the beach but on the way stumbled across an even rarer find coastal cliffs with landward dipping bedding planes. What? I hear you say… well read on Geogra-geeks for it is about to all be explained.

Coastline with landward dipping bedding planes. (Photo: Natasha Driscoll)

Where was this?

Montenegro is a small Balkan nation in southern Europe. Montenegro borders Croatia (to the North West), Bosnia and Herzegovina (to the North), Serbia (to the West) Kosovo and Albania (to the South).

Budva is a tourist town, which holds a small-stonewalled old town surrounded by younger (less attractive) buildings constructed in the rush to attract tourists. Currently, the businesses in the area are trying to out-compete each other in the bid to earn a quick buck from the passing trade.

Further south along the coastline between Petrovac and Bausunde lies the Petrovac-Rezevici hiking trail where we stumbled across a perfect example of a cliff with a landward dipping bedding plane.

Geogra-context: Cliff Profiles

Coastlines erode at different rates due to geology, destructive or constructive waves amongst many other causes. One component that can be considered in the rate of coastal recession and the stability of cliffs, is cliff profiles and their bedding planes. Don’t panic I have simply explained these terms below (I have even added some basic diagrams).

Bedding Planes

Formation of Sedimentary Rock (Drawing: Natasha Driscoll)

Bedding planes are small divisions in sedimentary rock separating younger rock (at the top) from the older rock (at the bottom). This happens as sedimentary rock forms from the falling of material and organic matter (dead plants and animals) to the bottom of a body of water (lake or ocean). Over time this sediment is pressed down by the new material falling on top of it, causing it to be compressed and after cementation turns into sedimentary rock.

Cliff Profiles: Horizontal Bedding Planes

Cliff Profiles refer to how the bedding planes align with the coastline. In the most simplistic of examples, the bedding planes will be perfectly horizontal, thus perpendicular to the sea.

Erosion at Coastal Cliffs with horizontal bedding planes (Drawing: Natasha Driscoll)

Cliffs with horizontal bedding planes would see weaknesses in the bedding planes or different layers being exploited by the sea, leading to a wave-cut notch. Over time as the wave-cut notch increases in size, the rock above would become unsupported and collapse into the sea. Resulting in the cliff retreating.

Cliff Profiles: Landward Dipping Bedding Planes

The coastline between Petrovac and Bausunde do not have a horizontal bedding plane, as seen above. Due to tectonic uplift* and pressure, the bedding planes can be distorted. This may result in, the otherwise horizontal bedding planes, dipping towards the sea, decreasing the cliffs’ stability, or towards the land increasing the stability.

The coastline between Petrovac and Bausunde where the cliff has landward bedding planes. (Photo: Natasha Driscoll)

This dipping has occurred at the coastline between Petrovac and Bausunde, leading to the bedding planes tipping towards the land; a cliff profile known as landward dipping bedding planes. Unlike the horizontal bedding plane, these are much harder to erode. These coastlines are more resistant as the bedding planes are at an angle that cannot be easily targetted by marine erosion*. Furthermore, as no wave-cut notch forms on landward dipping cliff profiles, the rocks above do not lose their stability. Resulting in a slower coastal recession rate in comparison to cliffs with seaward dipping or horizontal bedding planes.

Cliff with landward dipping bedding planes (Drawing: Natasha Driscoll)

Final thoughts

The tilt (landward dipping) of the bedding planes of the coastal cliffs between Petrovac and Bausunde are not only intriguing and beautiful, but they also act as the first line of defence for the coastline.

• What other ways have geographical features naturally defended themselves from the processes occurring to them?
• If everything else was to remain the same, but the bedding planes were horizontal; what would the coastline look like?

Please share your opinions to the questions and examples of other cliff profiles in the comments below.

Glossary

 *Tectonic Uplift – the process by which tectonic plates movements can result in the ocean floor emerging onto the surface.

* Marine Erosion: the wearing away of rock along the coastline by the sea. The four main processes are hydraulic action, abrasion, attrition, corrosion (solution).