Coasts Flashcards
Why do waves refract?
As waves approaches the coast at an angle, the side of the wave that is closest to the shore is in shallower water, so it moves slower, and the the wave bends to be almost parallel with the beach.
What is the difference between isostatic and eustatic sea level change?
Isostatic change is change in a local area due to an uplift of the land. Eustatic change is on a global scale due to a change in overall volume in the oceans.
What is a longshore current? How does it form?
A longshore current is a current that moves sand down the shore. It occurs because waves aren’t completely parallel to the shore so sand is pushed in one direction.
What are the erosional features of a beach?
A wave-cut cliff, wave-cut platform, marine terrace, sea cave, and sea arch.
What is a wave-cut platform?
A notch is carved into a cliff, part of the cliff collapses, and a platform is left below sea level.
What is a marine terrace?
A wave-cut platform above sea level.
What is a sea arch?
A natural bridge started at a sea cave.
What are the depositional features of a beach?
spits, baymouth bars, tombolos, and barrier islands.
What is a spit?
It is when longshore currents carry sand across a bay or inlet.
What is a baymouth bar?
It is when a spit completely connects across a bay/inlet.
What is a tombolo?
It is sand attached to an island from the shore.
What is a barrier island?
Dunes that drowned, a baymouth bar with breaks, or a scouring of sand pushing piles of sand towards the shore.
What is a berm?
A berm is a hill of sand along the shore.
What is the swash zone?
The area of the beach where waves wash up onto the shore.
What is a longshore bar?
A submerged or partially submerged sandbar that runs parallel to the shoreline.
How does the beach differ in the summer and winter?
In the summer the berm is bigger and the longshore bar is small. In the winter the longshore bar is extremely pronounced and the berm is smaller.
Why does the beach look different in summer and winter?
In the winter there are bigger waves that pull sediment back and in the summer there are small waves that push sediment towards the beach.
How do man-made structures like jetties interfere with the coast?
They affect the natural movement of sand and can trap sediment on one side of the structure.
What are some indicators of an emergent coast?
A wave-cut platform is above sea level. A once low marsh is becoming high.
What are some indicators of a submergent coast?
Flooded dunes, submerged marine terraces, and a high marsh is becoming lower.
