How do Humans Change Landforms?

A seismograph records movements in the Earth’s crust.

A shake table simulates the ground movements during an earthquake.

GPS receivers help seismologists measure the movements of faults and plates that cause earthquakes.

A levee is a wall of earth or concrete, built beside a river, that holds back rising flood waters.

Dams are built across a river to control the amount of water moving downstream.

Beach erosion causes some beaches to shrink and boating channels to fill up making them too shallow for ships.

A jetty is a wall-like structure that sticks out into the ocean. Jetties help stop beach erosion by breaking up longshore currents, trapping sand and small rocks up shore of the jetty.

Artificial reefs are made of many kinds of objects (like a sunken ship).

Hundreds of old subway cars, and other large objects, have been dropped into the ocean off the coast of Georgia.