Our planet is laced with shorelines, more than a million miles of them in all. They are infinitely varied in form, composition, and geographic character, but all have one trait in common: a capacity for unending change. This change comes from a wide variety of sources including earthquakes, tides, volcanoes, glaciers, land use, and hurricanes, but one system stands above all these as the premiere coastal change agent: the geomorphic system of waves and currents. This system operates almost everywhere all the time and is responsible for doing the lion's share of the work in eroding coastal land and transporting and depositing sediment. Our mission here is to understand how that system works, what drives it, and how it is capable of shaping the landforms of this celebrated environment. We also want to know how all this relates to humanity, because humans are particularly fond of the sea coast. Each year more and more people crowd into coastal lands throughout the world. We begin with a brief examination of the various systems that move sediment along the coast and then go on to the master system of wind waves, currents, wave erosion, and coastal landforms.
It was a glorious summer morning. We loaded our little boat for a trip along the Lake Superior shore. “What are we looking for, anyway?” Jim asked. “Shoreline features,” I said without thinking.