Destructive Coastlines

Abstract

Coastal morphology and deposits are dependent on the geologic setting and history, climate, oceanographic environment and sediment supply, coastline orientation and exposure and the rate of past and modern sea level changes. Along secondary coasts the major geological forces operating at a shoreline – the line where the water surface intersects the shore – are waves and tides. Over the last 6000–7000yrs sea level has only oscillated slightly around its present day position. Therefore, for millennia waves have rolled onshore with calm troughs during quiet weather or breaking with fearful violence during storms and transforming, eroding and reshaping the coastlines around the world. In this chapter we will outline the result of abiotic destructive processes by these hydrodynamic forces from the sea and briefly discuss coastal forms produced by salt weathering. However, living organisms can affect coastal geomorphology on a grand scale with changes even perceptible on a human time scale. Here, we see how tiny organisms in the coastal zone create and shape coastal landforms and start with an important one: Bioerosion.