Understanding Geological Factors in Coastal Systems
Geological Factors play a fundamental role in shaping coastal landscapes and processes. The interaction between rock types, structures, and ocean dynamics creates diverse coastal formations that evolve over time through complex systemic relationships.
Lithology, which encompasses the physical and chemical properties of rocks, significantly influences coastal erosion rates and landform development. Different rock types exhibit varying levels of resistance to erosive forces. For instance, clay formations demonstrate weak lithology due to their loose particle bonds, making them highly susceptible to erosion and mass movements. In contrast, basalt, composed of dense interlocking crystals, shows remarkable resistance and often forms prominent coastal features. Chalk and carboniferous limestone present unique challenges as they're vulnerable to chemical weathering through carbonation.
Definition: Lithology refers to the physical and chemical composition of rocks, determining their resistance to coastal processes and weathering.
The structural properties of rocks, including jointing, bedding, and faulting patterns, determine coastal planform at regional scales. When rock outcrops run parallel to the coastline, they typically produce straight, concordant coasts. Conversely, rocks positioned at angles to the coast create distinctive headland and bay formations, known as discordant coasts. The angle of rock dip particularly influences cliff profiles - horizontally bedded and landward-dipping strata provide stability, while seaward-dipping strata often follow bedding plane angles.
Example: In a coastal system example, the Dorset coast demonstrates how varying rock resistance creates distinctive landforms - with harder Portland limestone forming headlands while softer clays form bays.