The Beach Book describes the physical processes and materials that create and change the “edge of the sea.” Sunbathers who visit the shore on day trips or week-long vacations notice that the beach is different each time they return. It can be wide or narrow, pitch steeply or slope gently into the water, be rocky or sandy. Swimmers feel the currents. Many popular beaches are on barrier islands with sand dunes. Marshes that feed and shelter fish and crabs often are near beaches. Anglers and boaters navigate through tidal inlets, experience the roll of waves, and must remember the hours...

For many people, the beach is the shore. It is where they go to play in the sea, to sunbathe, to play beach volleyball, and to dance to beach music. In some uses, the words “shore” and “beach” are synonymous. An unemployed or a retired mariner is said to be “on the beach.” To the coastal scientist, however, a beach is a specific, physical environment. In Beaches and Coasts, Richard Davis and Duncan FitzGerald define it as a “deposit of unconsolidated sediment, ranging from boulders to sand, formed by wave and wind processes along the coast. The beach extends from...

An afternoon breeze off the water lessens the discomfort of a hot summer day in the sun, flies kites, dries bathing suits and beach towels, and blows gnats and mosquitoes away from the beach. Wind, especially storm wind, is an important part of beach processes. Very strong winds, such as hurricanes, affect much more than just the beach. Even moderate winds generate waves, which are important mechanisms that alter the shore and which add to our enjoyment of a day at the beach.

The sun is the essential driver of wind. As the sun heats the atmosphere, the sea, and...

Waves move energy from one place to another. Waves that break on the beach and rock boats also erode the shore and modify beaches. Wind causes most ocean waves, so they are called wind waves. When waves are in deep water and cannot interact with the seafloor, gravity is the major force acting to damp them; gravity tries to restore the water to a flat surface. Because of the importance of gravity in the physics of wind waves, they also are called gravity waves. There are several other ways to classify waves.

When wind, even a light breeze, blows across...

In studying tides, we have to think of the sun and the moon. Tides are a product of the gravitational attractions between Earth and the moon and between Earth and the sun. We also have to switch our thinking about the arrangement of the solar system back to that of our ancient ancestors and imagine Earth as being the center of the universe. The rotation of Earth on its axis and the revolutions of the moon and the sun “around” Earth cause the tides. The three-dimensional shapes of the ocean basins further modify the tides.

First, we take Isaac Newton’s...

Sediments collectively are the many solid particles of gravel, sand, silt, and clay. According to the Glossary of Geology, sediments originate from the weathering of rocks and are deposited by air, water, or ice. They also accumulate by chemical precipitation from solution or from secretion by organisms. They form in layers on Earth’s surface at ordinary temperatures in a loose, unconsolidated form. Sediments are the stuff that makes up beaches, sand dunes, and marshes and that forms the seafloor.

As with many collective terms, there are several schemes for classifying sediments. The terms within each scheme can intermix and lose...

Barrier spits and barrier islands buffer the mainland shore from the wave energy of the ocean. The origin of barrier spits is clear even to unsophisticated observers. A strong, net longshore current transports sediments from a source area, often a promontory. As the sediments move with the longshore current, the spit grows longer. Wave refraction and diffraction wrap around the end of the spit, creating a hook, or “re-curve,” as some of the sediments and the spit turn the corner into the back-barrier bay.

The sediments along a spit show the consequences of the transportation processes. Sediment particles that are...

Sand dunes and salt marshes are common features near beaches. Sand dunes occur where there is sufficient sand and enough wind to move it. They are an aeolian deposit, meaning that they develop from wind-blown sediments. In Greek mythology, Aeolus is the god of the winds. According to the Army Corps of Engineers’ Shore Protection Manual, “Winds blowing inland over the foreshore and berm move sand behind the beach to form dunes. Grass, and sometime bushes and trees, grow on the dunes, and the dunes become natural levees against sea attack. Dunes are the final natural protection line against wave...

Why does sea level change? The concepts of sea level and sea-level change are complex and can be confusing. What does sea-level change, more usually called sea-level rise, mean? How is sea level measured at any one place? How is it measured throughout a region or around the world? How is the change in sea level measured, and why does it matter?

When you spend a day at the beach, without realizing it, you observe sea-level change on two time scales: the second-to-second scale of waves and the hour–to-hour scale of tides. These two processes highlight the problems of...

Storm surge is the difference between the predicted, astronomical tide and the actual water level (figure 9.1). Although we think that storm surges cause unusually high tides, they also can lower anticipated water levels. The observed water level, occasionally called a storm tide or weather tide, combines the storm surge and the predicted, normal water level.

Wind, waves, and barometric pressure create the storm surge. Sustained, strong winds blowing toward the coast push seawater, so it piles up on the shore. Additionally, Ekman transport causes the water immediately below the wind-driven surface to flow to the right of the wind...

Most people’s gut reaction to the erosion of beaches is that it must be stopped. But erosion is a natural phenomenon whose basic causes tend to be relatively simple: waves and currents, usually during sporadic storms. Ongoing sea-level rise also plays a role. As the water rises, the leading edge of the ocean moves landward, aggravating erosive processes. Storm waves chew the beach and eat the base of the foredune or backshore region. By excavating the area behind the beach, the storm waves make “new” sediment available to be carried by the longshore-drift system, which during a major storm operates...