Chapter 15: The Dynamic Ocean Flashcards
Two types of surface circulation?
Ocean currents- masses of water that flow one place to another
Surface currents- develop from friction between ocean and wind
The Coastal Zone order
Shoreline- contact between land and sea
Shore- lowest tidal and highest tidal level affected by storm waves
Coastline- seaward edge of the coast
Beach- accumulation of sediment along landward of ocean
What is the definition of a wave?
Energy traveling along the interface between ocean and atmosphere. Gets energy from the wind
The two components of a wave?
1) Crest- top of wave
2) Trough- bottom of wave
The measurements of a wave?
A) Wave height- vertical distance between trough & crest
B) Wavelength- horizontal distance between crests & troughs
C) Wave period- time interval for one full wave to pass a fixed position
The wave height, length, and period depend on?
1) wind
2) ) length of time the wind blows
3) fetch- distance that he wind travels
As the wave travels, the water passes energy by?
Moving in a circle
-waveform moves forward
The color and type of beach sand reflects what?
the local geology.
Beaches are composed of whatever material is available.
How does beach material always keep moving?
Wave energy moves large parts of sand both parallel and perpendicular to the shoreline
What is Wave Refraction?
the bending of a wave!
-waves approach shore at an angel, but refract and become parallel when encounter w/ shallow seafloor
Wave erosion does what to a coastline?
Straightens the coastline out
What is a beach drift?
Sediment moves in a zigzag pattern along the beach face
What is a Longshore Current?
Current the surf zone
Flows parallel to the shore
Moves a lot more sediment than beach drift
Erosional Features:
Wave-cut Cliff
originate due to the cutting action of the surf against the base the coastal land
Erosional Features:
Wave-cut Platform
A relatively flat, bench-like surface left behind by the receding cliff
Erosional Features:
Marine Terrances
occur when a wave-cut cliff is uplifted above the sea by tectonic forces
What is associated with headlands?
Sea arch & sea stack
Four depositional features?
- Spit- ridge of sand from ridge to mouth (hooks landward)
- Baymouth Bar- sand bar crosses all of the bay
- Tombolo- sand that connects island to mainland
- Barrier Islands- mainly along Atlantic and gulf coastal plains …relatively flat
How does a Barrier Island originate?
A. spits that served from mainland by wave erosion
B. sand heaped up after being sourced from ocean bottom in a large storm
What is Hard Stabilization?
building structures to control coastline erosion and deposition
Three types of structures that stabilize the shore?
Groins
Breakwaters
Seawalls
What location is a great example of groins?
New Jersey shoreline.
What is a groin?
traps sand from longshore current migration, limiting erosion
What is a breakwater?
barriers built offshore & parallel to the coast… protect boats from waves
What are seawalls?
Structures armor coast against force of breaking waves
Two alternatives to hard stabilization?
- Beach nourishment: adding sand to beach
- downside: expensive and not a permanent fix
- Relocation buildings: away from the beach
Why is shoreline classification so difficult and what is is based on?
difficult= they are always moving!
based on= sea level
How much land is exposed with a Emergent coast and a Submergent coast?
Emergent coast- more land exposed
Submergent coast- less land exposed
Features of an Emergent Coast?
A. Wave-cut cliffs
B. Marine terraces- once flat has been techtonically uplifted
Features of a Submergent Coast?
A. Highly irregular shoreline (sea level rise
)
B. Estuaries= flooded river valleys
C. Fjords= flooded glacial valleys
What are tides?
are the daily changes in the elevation of the ocean surface
How are the changes in tides caused?
gravitational forces exerted upon Earth by moon and sun
What is a Spring tide?
kind of like a tidal wave
- Occurs during new and full moons
- Produce a large daily tidal range
What is a Neap tide?
scarcely touching (“without power”)
*Occurs when he sun and moon are at right angles
Three tidal patterns that influence tides?
1) Shape of the specific coastline
2) Configuration of the ocean basin
3) Water depth
Two types of tidal currents?
1) Flood current- advances into coastal zone
2) Ebb current- moves seaward
What is a Tidal current?
Horizontal flow of water accompanying the rise and fall of tides
How do Rip Currents develop?
When a wave attack is straight on to the shore
*water piles up on the beach and must return seaward
