Activity 4: Faults
WHOSE FAULT IS IT?
Earth's crust is broken into many pieces called plates. Within each plate, smaller breaks are found along which movement occurs. These breaks are called faults. Students will use blocks of wood to distinguish among fault types and describe the movement along each type.
Instructional Method: Experiment
Goal: Introduce students to three different fault types and the movements along each type.
Objectives: Students will be able to:
Activity time: 30 minutes
A fracture in rock along which movement occurs is called a fault. Geologists consider faults to be a planar break in rock, along which there has been movement of one side relative to the other. Pieces of crust on either side of a fault are known as fault blocks. Each block moves as an individual unit during earthquakes. It is helpful to imagine breaks in this manner because it allows you to use common objects to simulate fault block interactions.
Faults can be very short or can be miles in length, continuous or intermittent. There are three common fault types, classified according to fault block motion. They are:
Faults can often be seen at the surface. Many man made items are affected by fault movement: a fence that has been separated, underground pipes that are sheared, or a canal that has been set off course by a fault.
In many places, faults are detected by rock associations. To look for a fault in nature you search for younger rock beside older rock (normal or reverse faults) or older rock on top of younger rock (thrust faults). In many places along a fault plane broken rock (fault breccia) or even powdered rock (fault gauge) are found. Sometimes if the plane of the fault is visible, there are little lines called slickensides on the rock surface showing the direction of fault movement, created by the scraping of the rocks against one another. Large fault planes are often exposed at the surface and can be seen cutting across hills and mountains.
When movement occurs between two fault blocks we feel an earthquake. For more information about earthquakes and movement caused by earthquakes, link to Surfing Rock Waves. The following activity uses wood blocks to experiment with fault movement.
Are there any faults in your area? If so, do you know which type is near you? Which type of fault would result in the most damage? Why? How do you know?
Play-doh can be used in place of wood blocks. Use three different colors. Stack the colors forming layers. Once the layers are formed and stacked, cut a diagonal or vertical line in the middle of the dough to represent the fault surface. Now use the two blocks of Play-doh to perform all the fault movements.
Included National Parks and other sites:
Utah Science Core:
5th Grade Standard 2 Objective 1,2,3