Ocean Motion and Coastal Landscapes: A Definitive Study Guide to Waves and Tides

Curriculum Connection 2: This material investigates and interprets the vital links between water, climate, and landforms.
Learning Destination 2.1: The primary objective is to gain the capability to explain exactly how waves and tides function to change the landscape.
Focusing Question: The central inquiry of this study is: "How do waves and tides interact with shorelines to change the landscape?"

Waves: The rhythmic movement of energy across the surface of the ocean.
Swell: The steady movement of smooth waves near the shore, resulting from winds and storms far out at sea.
Erosion: The process of transporting rock fragments and soil from one location to another.
Weathering: The gradual wearing away of Earth's surfaces.
Deposition: The accumulation and building up of natural materials in new locations.
Tides: The daily change in the water level of the oceans, culminating in a cycle of high and low water levels.

Ever-Changing Environments: The coastal landscape is in a state of constant flux, reflecting the continuous processes of weathering, erosion, and deposition.
Primary Drivers of Change: A combination of waves, tides, wind, and ocean currents all contribute to the physical shaping of the coastline.
The "Sand Robbers" Metaphor: Gertrude M. Jones illustrated the process of coastal change through the following poem: * "The little waves ran up the sand, * All rippling, bright and gay. * But they were little robbers, * For they stole the sand away, * And when they'd tossed it all about, * They piled it in the bay."

Origins of Waves: Ocean waves are primarily created by winds.
Wind Sources: Winds are generated by a combination of the Earth’s rotation and the uneven heating between the equator and the poles by the Sun.
Growth Factors: Waves begin in the open sea. The height of a wave is determined by three specific variables: * How fast the wind blows. * How far the wind blows (fetch). * How long the wind blows.
Anatomy of a Wave: Ocean waves behave similarly to light, sound, and radio waves and are labeled using standard terminology: * Crest: The highest point, or top, of the wave. * Trough: The lowest point, or bottom, between two waves. * Still-Water Level: The level the water would occupy if it were perfectly calm and still. * Amplitude: Defined as half of the wave height, measured as the distance from the crest to the still-water level. * Wavelength: The measurement from crest to crest, or the spacing between wave peaks. * Frequency: The number of waves that pass a fixed point in a given amount of time.

Normal Wave Height: Standard winds typically produce waves ranging from $2 \, \text{m}$ to $5 \, \text{m}$ in height.
Extreme Wave Height: A hurricane is capable of producing waves as high as $30 \, \text{m}$ , which is taller than a typical school building.

Energy vs. Water Movement: In deep water, a wave represents a forward motion of energy, not the water itself. The water does not move forward with the wave.
Vertical Orbits: If a single drop of water is tracked during a passing wave, it moves in a vertical circle, returning to a point near its original position once the wave ends.
Effect of Depth: These vertical circular motions are most obvious at the surface. As depth increases, the circular effect decreases until it disappears entirely at a depth of approximately $\frac{1}{2}$ a wavelength below the surface.
Energy Transfer: Energy is transferred between particles as they bump into one another. An object placed in the ocean simply bobs up and down (raised to the crest and lowered to the trough) as the energy passes. If an object moves forward, it is typically due to wind, not the waves themselves.

Swell Formation: Smooth, steady waves near the shore (swells) originate from distant storms and winds far out in the open ocean.
Approaching the Shore: As a wave reaches the shoreline, the water depth decreases.
Friction and Slowing: When the trough of the wave touches the seabed, it is slowed by friction with the shore.
The Break: 1. The crest is not slowed by friction, unlike the trough. 2. As a result, the wavelength decreases. 3. The amplitude (height) of the wave increases. 4. The crest eventually outruns the trough, curls over, and collapses (breaks) onto the shore.

Reshaping Shorelines: Waves are highly effective agents of erosion, transportation, and deposition.
Coastal Landforms: Wave action specifically shapes sea cliffs, resulting in various coastal landforms like those seen on the coast of Vancouver Island or Vallarta Nayarit, Mexico.
Beach Formation: Beaches are formed when rocks carried by waves crash together, eroding into smaller, smoother rocks and eventually into sand particles.
The Settling Process: On gently sloped shorelines with calmer waters, these sand particles have the opportunity to settle out of the water, forming broad stretches of sand (e.g., Bavaro Beach in Punta Cana, Dominican Republic).

Definition of Tides: Tides are the daily change in ocean water levels, typically resulting in two high tides and two low tides every day.
Celestial Causes: Tides are caused by the gravitational pull of the moon and the sun. The water follows the moon as it cycles the Earth.
Tidal Shoreline Reshaping: * High Tide: During high tide, waves have the power to pick up and carry sand and other materials away from the beach. * Low Tide: The waves deposit this material elsewhere when the tide is lower, changing the coastline's shape.
Spring Tides: These are the highest tides. They occur when the moon is full or new and is aligned with the sun. This alignment combines the gravitational pull of both bodies, resulting in very high high tides and very low low tides.
Neap Tides: These represent the smallest tidal movements. They occur during the moon's quarter phases when the Earth, Moon, and Sun are positioned at right angles. This configuration causes the gravitational bulges to cancel out, resulting in minimal difference between high and low tide.

Waves are primary agents for the erosion, transportation, and deposition of sand and rock.
The motion of ocean water is the fundamental driver behind the evolution of coastal landscapes.
Tides serve as effective transportation agents, moving materials across the shoreline during high and low cycles.