ch14 flashcards
(36 cards)
wave formation
Waves are generated primarily by wind transferring energy to the ocean’s surface. The size and energy of a wave depend on wind speed, duration, and the distance over which it blows (fetch)
wave refraction
The bending of waves as they approach shallow water and encounter varying bottom topography, causing wave energy to focus on headlands and disperse in bays
wave reflection
The bouncing back of waves from a steep or vertical shoreline feature, such as a sea wall or cliff, causing waves to return seaward with reduced energy
shoreline erosion
The removal of coastal material by wave action, currents, and tides, shaping features like terraces, stacks, arches, and headlands over time
terraces (marine terraces)
Flat, step-like surfaces formed by wave erosion and uplift of the coast, exposing former sea floors as elevated platforms
sea stacks
Isolated pillars of rock offshore, formed when waves erode arches or headlands, leaving resistant remnants standing in the sea
arches (sea arches)
Openings carved through headlands by wave erosion. When the roof eventually collapses, they can form isolated sea stacks
headlands
Protrusions of land that extend into the ocean. They are more resistant to erosion than adjacent areas, causing wave energy to concentrate and erode them
coves
Small, sheltered bays or inlets formed where waves erode softer rock behind headlands, creating protected, often rounded indentations in the coastline
longshore current
A current that moves parallel to the shore, formed by waves approaching the coastline at an angle and transporting sediment along the beach
longshore transport
The movement of sediment (sand, gravel) along the shoreline by longshore currents, shaping beach profiles and forming various coastal features
spit
A narrow, elongated ridge of sand or gravel extending from the shore into a body of water, created by longshore drift
barrier bar (Baymouth bar)
A ridge of sand or sediment that extends across a bay, sealing it off and creating a lagoon, formed by longshore transport
tombolo
A bar of sand or sediment connecting a former island to the mainland or another island, formed by wave refraction and longshore transport
groin
A man-made structure built perpendicular to the shoreline to trap sediment and reduce erosion on one side, but often causing increased erosion downstream
jetty
A structure extending into the ocean at the mouth of a river or inlet, designed to stabilize channels and prevent sedimentation, but can alter longshore transport and cause erosion elsewhere
breakwater
An offshore structure parallel to the shore that breaks incoming waves, providing calm waters behind it. It can cause sediment buildup behind it and changes in coastal erosion patterns
emergent coastline
A coastline that has been uplifted or where sea level has fallen, exposing previously submerged features like marine terraces and revealing a “stepped” coastal landscape
submergent coastline
A coastline that has been flooded by rising sea level or sinking land, resulting in features like drowned river valleys (rias) and irregular shorelines
barrier island
A long, narrow island of sand parallel to the mainland coast, formed by wave action and longshore drift, providing protection to the shore behind it
Baymouth bar
A sandbar that completely crosses a bay, isolating it from the main body of water, forming a lagoon behind it
beach
A depositional landform composed of loose sediment, primarily sand and gravel, washed by waves and tides and shaped by coastal processes
beach face
The sloping surface of a beach that is washed by waves, lying between the low tide and high tide marks
berm
A nearly horizontal plateau on the beach formed by the deposition of sediment at the high tide line
