Earth Studies HW 11

Once hard stabilization of a coast is initiated by construction of structures such as groins and breakwaters, why is it often necessary to continue building more of these structures?

Construction of groins and breakwaters disrupts the natural flow of sediments along the coast.

In the long term, what do beach drift and longshore current do?

Move sediment parallel to the shoreline

Which pattern of particle movement occurs when wave movement is oblique to the beach?

Particles move on the beach in a zigzag pattern.

Which term is used by geologists to identify the time interval between the passage of successive wave crests or troughs?

Period

What would you do to both grow a large beach and protect a harbor mouth?

Place two jetties on either side of the harbor mouth, and build a breakwater upcurrent from the harbor mouth.

Which situation occurs in the downcurrent direction when a groin is constructed on a beach to prevent erosion of a beach by longshore currents?

Sediment is removed on the downcurrent side of the groin.

Which of the following structures are types of coastal stabilization structures?

breakwaters groins jetties

How do jetties protect harbor entrances?

by inhibiting the deposition of sand in the harbor mouth

Which pattern best describes the motion of water particles in a wave in the open ocean?

circular orbit

In which direction does the longshore current move?

parallel to shore

Which feature results from the collapse of a sea arch?

sea stack

Why are coastal stabilization structures built along coastlines?

to protect coastal property from wave erosion to stop beach sand erosion

What is the longshore current?

water forced by waves to move along the shore

Occasionally, when a sea stack is formed, accumulations of sand are deposited behind it, producing a tombolo. Which process is responsible for the creation of the tombolo?

wave refraction

Which term is used to define the distance between successive wave crests or troughs?

wavelength

When waves approach shore and touch bottom, what happens to the wave form?

wavelength decreases and height increases

An open water wave with a wavelength of 4 meters moves onshore into shallow water. At what depth does the wave begin to touch bottom?

2 meters

If the wave period changes so that it is half its original value, how does this change the wavelength?

The wavelength will be twice as long.

When a headland of resistant bedrock extends out into the ocean, which statement best describes wave action in proximity to the headland?

Wave energy is focused on the headland.

Which process is directly responsible for the development of notches, cliffs, and platforms?

abrasion

Which way would sediment move if NO beach drift existed?

at an angle to shore