Chapter 16 -- Shore and Shoreline Process Flashcards
The area from low tide to the highest level of land affected by storm waves
A ______ is the broader area which includes the shoreline, nearshore sandbars and islands, and sand dunes, marshes, sea cliffs.
Shoreline
Coast
Regular fluctuations of the sea in response to the gravitation attractions of the sun and moon.
Usually two cycles per day
Tides
27million x smaller than the sun ##% stronger gravitational pull ###x closer ## day revolution Tides occur ## minutes later each day
Moon
46%
390x closer
50 Minutes
Results from sun and moons combined effect.
Average 20% higher
Spring Tides
Results from the sun and moon at right angles
Average 20% lower.
Neap Tide
Oscillations of the water surface which transmit energy, in the direction of wave movement
Waves
Parts of a Wave
Highest point of the wave
Crest
Parts of a Wave
Lowest point of the wave.
Trough
Parts of a Wave
Distance from crest to crest.
Wavelength
Parts of a Wave
Time it takes for successive crests to pass a given point.
Period
Parts of a Wave
half of the wavelength
Wave Bass
Parts of a Wave
Wavelength divided by the Period
Speed
What are the four causes of waves?
Volcanic Eruptions
Faultings
Landslides
Wind
What are the three controlling factors of waves?
Wind Velocity
Wind Duration
Fetch
As waves enter water shallower than the wave base, the wavelength decreases but the wave height increases.
Waves then become too steep and plunge forward as ______.
Breakers
Area extending seaward from the upper limit of the shoreline to just beyond where the waves break.
Nearshore Currents
The bending of waves so that they are more nearly parallel to the shoreline
Wave Refraction
Current resulting from wave refraction that flows parallel to the shoreline
Responsible for much transport and deposition.
Longshore Currents
Narrow, surface currents which rapidly carry water from the nearshore zone seaward through the breaker zone. Extremely dangerous to swimmers.
Rip Currents
Shoreline Erosion
Develop where erosion exceeds deposition.
Sea Cliffs
Shoreline Erosion
Formed as a gently sloping, beveled surface abraded by wave action
Wave-Cut Platforms
Shoreline Erosion
Wave-cut platforms that have been raised above sea level.
Marine Terraces
Shoreline Erosion
Seaward projecting parts of the shoreline
Headlines
Wave refraction around a rocky headland may erode the headland to form ___ _____ on each side
Sea Caves
With continued erosion, the caves merge to form a ___ ____.
Sea Arch
A collapsed arch leaves isolated ___ ______.
Sea Stacks
Deposits of unconsolidated sediment extending landward from low tide to the edge of the dunes or a sea cliff.
Most common shoreline depositional feature.
Are continually modified by the action of the waves, longshore currents, tides, and storms
May be continuous or isolated pocket.
Beaches
Components of Beaches
____________ is usually dry and water that rolls back down the beach after waves break
Backshore
Components of Beaches
_______ are platforms that slope gently landward
Berms
Components of Beaches
_______ ____ is exposed to the wave swash
Beach Face
Components of Beaches
___________ is covered by water in high tide.
Foreshore
Components of Beaches
______ is water that washes up on shore.
Swash
Structures projecting seawards at right angles to the shoreline
Often built to widen a beach or slow erosion.
Groins
Fingerlike projection of a beach into a body of water such as a bay.
Recurved spits have a curved free end.
Spits
Spit that has grown until it completely closes off a bay from the open sea.
Both can be problematic where bays need to be kept open.
Baymouth Bars
Type is spit extending out from the shoreline to and island.
Forms on the shoreward side of an island by refracted waves.
Tombolos
Long narrow islands of sand formed at short distance offshore
Beach side is smoothed by waves
Land side is irregular due to storm shower deposits
Defined by beaches, wind blown dunes and a marshy area.
Barrier Islands
Characterized by abundant sediment, wide sandy beaches, deltas and barrier islands (US Gulf Coast)
Depositional Coasts
Steep and irregular, and lack well developed beaches (many west coast US beaches)
Erosional Coasts
Found where sea level is rising with respect to the land
Submergent Coasts
Found where land has risen with respect to sea level.
Tectonics, isostacy etc.
Emergent Coasts
