Coasts Flashcards
Crest
Top of a wave
Trough
Low areas between waves
Swah
Movement of water and load UP the beach
Backwash
movement of water and load DOWN the beach
Velocity
Speed a wave is travelling
Wavelength
Distance between two crests or troughs
Wave height
Distance between the crest and trough
Wave frequency
Number of waves per minute
The size and energy of a wave is influenced by
How long the wind had been blowing
The strength of the wind
How far the wave has travelled (the fetch)
Why coastlines are under threat
Polluting
Rising sea levels
Destroying wildlife
Importance of coastlines
Sustains community Vacation/tourism Transportation Property value Eco-tourism Oil and gas extractor
What causes tides
changes in how much the moon’s gravity pulls on different parts of Earth
Spring Tides
Spring tides occur twice a month, at new moon and full moon. The combined force of the moon on one side of the earth and the sun on the other, produces a tide with the greatest difference between consecutive high and low tides
Neap tides
Produced at the moons first and third quarter, when the line between the moon and sun is at 90 degrees to the angle between the earth and moon. They occur twice a month
Process of forming tides
The force of gravity pulls the sun and moon toward each other. The moon’s gravity pulls Earth, leaving water behind an additional high tide. Low tides occur between high tides. There are two low tides and two high tides per day.
Constructive waves
Associated with calm weather Less powerful Break on shore depositing material Responsible for transporting material Swash is stronger than backwash
Destructive waves
Associated with storm conditions
Created when a wave energy is higher with a large fetch
Associated with erosion
Backwash is stronger than swash
The process of longshore drift
Waves hit the beach at an angle and then pulls the material straight back. Then repeats and sends them back to the beach at an angle to deposit it again. This action can erode away beaches or completely take them away
In the process of longshore drift, why does beach material get washed up the beach at an angle?
Due to the prevailing winds pushing the waves at an angle to the beach
In the process of longshore drift, why does beach material wash back down the beach at right angles to the coastline?
Because the force of gravity pulls the material straight back
Beach grading: (sorting)
Higher wave energy carries the largest particles.
Energy is lost in the backwash due to percolation
Over time, wave action will “sort” the beach materials from coarse to fine
Backwash has more friction than swash, therefore swash is stronger