The Coastal System

The Study of Coasts Coasts can be studied in several different ways dependent upon their classification: Erosional or depositional Sediment type (clastic: shingle and sand; or muddy) Submergent or emergent Tectonic setting Process-based: wave dominated, tide dominated and wind dominated - the agents of erosion

Wave Dominated Tide Dominated Wind Dominated Shore Platforms Mudflats Sand Dunes Cliffs Sandflats Beaches Salt Marshes Spits, Tombolos Mangroves Deltas Deltas Questions & Answers Cause and Effect Knowledge & Understanding Energy High Low (French, 1997)

Coastal Processes Coastal Form Wind, Waves, Tide, Currents Weathering, Erosion, & Deposition Coastal Form Dynamic over Space & Time Equilibrium Wind, Waves, Tide, Currents Sediment Movement

Cliffs and Shore Platforms The Coastal System ENERGY WAVES TIDES WIND GEOLOGICAL STRUCTURE MATERIALS Dominant Less Dominant Terrestrial Marine Coarser Finer Cliffs and Shore Platforms Mudflats Coral Reefs Beaches Sand Dunes (Hansom, 1988)

The Coastal System Coastal Systems: coastal systems vary primarily in response to wave intensity and tidal currents breaking waves (and resultant currents) provide most of the systemic energy several additional factors also influence coastal processes and landforms original geology of the coastline relative 'erodibility' of regional bedrock sea level variations (global and local tectonic or glacio-eustatic changes) coastal systems typically characterized as erosional or depositional erosional or depositional nature of any coastline varies with the systemic energy

Weathering & Erosion What is? Weathering: Breakdown of rock (Geology) to form sediment in situ Weathering is a set of physical, chemical and biological processes that alter the physical and chemical state of rocks and soil at or near the earth's surface. Rock and soil is altered physically by disintegrating and chemically by decomposing. Nearly all weathering involves water, mostly directly: frost shattering, wetting and drying, salt weathering, and all chemical weathering is in solution. That is, weathering is climatically driven and thus the term weathering. Because weather and climate occur at the earth's surface, the intensity of weathering decreases with depth and most of it occur within less than a metre of the surface of soil and rock. Erosion:Transport of weathered material from one location to another...The wearing away of land or the removal of beach and/or dune sediments by wave action, tidal currents, wave currents, drainage, or wind. Erosion includes, but is not limited to, horizontal recession and scour and can be induced or aggravated by human activities.

Erosional & Depositional Coastal Landforms