Cliff

In general, a cliff is identified as being “a mass of rock that rises very high and is almost vertical, forming near the ocean, high in mountains, or as the walls of canyons or valleys,” and can be spotted with waterfalls, which “tumble over cliffs” [2].

The processes that form cliffs tend to be “erosion and weathering,” with “tiny pieces of rocks broken off by weathering, called sediment or alluvium” and erosion being the “transportation of this sediment." Where cliffs form inland, “sediment is often carried away by rivers or winds” [2].

Two other means through which cliffs form are through glacial movement and tectonic activity. When the earth began to exit the ice age, “glaciers began moving across earth, forming some depressions as they flowed across the globe,” creating “expansive cliffs” with their “tremendous weight." With tectonic activity, “the plates shift from time to time” and may come into contact with one another, creating “huge pressure, forcing one of the plates to move upwards and protrude” [3].

Additionally, near the ocean, cliffs are “common features of a coastline, shaped through a combination of erosion and weathering – the breakdown of rocks caused by weather conditions,” and cliff types are recognizable with how “sand and clay eroding easily to create gently sloping cliffs” whereas “hard rock, e.g. chalk, is more resistant and erodes slowly to create steep cliffs” [1]. This process occurs in several steps, with “weather weakening the top of the cliff,” followed by a “wave-cut notch” created by the cliff base being worn away at by the sea, which then increases in size, “causing the cliff to collapse” [1]. The “joints, fissures, and softer strata” which “are especially vulnerable” at the cliff base aid in this process of weathering and erosion [5]. The “backwash carries the rubble towards the sea” and this continues to occur, with the cliff “continuing to retreat” [1].

These maritime cliffs (cliffs near the sea) have “limited accessibility,” which is equated with “limited potential for plants to gain a foothold,” leading to a majority of the vegetation occurring “at the top, where the slope is gentler and less severely exposed” [4].

References

[1] British Broadcasting Corporation (BBC). (2021). BBC Bitesize: Coastal landforms. Retrieved (2021, July 14), from https://www.bbc.co.uk/bitesize/guides/zsfwcwx/revision/4

[2] Caryl-Sue & Evers, J. (2013, March 4). Cliff. National Geographic Society. Retrieved (2021, July 13), from https://www.nationalgeographic.org/encyclopedia/cliff/

[3] Misachi, J. (2018, March 1). What Is A Cliff And How Is It Formed? World Atlas. Retrieved (2021, July 14),
from https://www.worldatlas.com/articles/what-is-a-cliff-and-how-is-it-formed.html

[4] The Wildlife Trusts: Protecting Wildlife for the Future. (n.d.). Maritime cliff. Retrieved (2021, July 14), from https://www.wildlifetrusts.org/habitats/coastal/maritime-cliff

[5] US Army Corps of Engineers: Institute for Water Resources Website. (n.d.). Waves and Sea Cliffs. Retrieved (2021, July 14), from https://www.iwr.usace.army.mil/Missions/Coasts/Tales-of-the-Coast/Coastal-Dynamics/Waves/Waves-and-Sea-Cliffs/