LEQ: How do stress forces in Earth’s crust form mountains and what kinds of mountains are formed from the stress? Key Terms: fault block mountain, upwarped mountain, folds, folded mountain, anticline, syncline
Mountain Building • Please turn to page 106 in your textbook. • Stress forces produced by plate movement can build up mountains on Earth’s surface. • The process occurs over millions of years • The types of mountains formed from stress forces are: • Fault Block Mountains • Upwarped Mountains • Folded Mountains
Mountains formed by Faulting • When movement along faults moves blocks of rock up or down. • Caused by dip slip faults. • Uplift occurs over millions of years • Types of mountains formed: • Fault block mountains. • Upwarped mountains.
Fault Block Mountains • When normal faults uplift a block of rock. • Caused by the stress force of tension. • View some images of fault block mountains at this link.
Upwarped Mountains • When reverse or thrust faults uplift a block of rock. • Caused by the stress force of compression. • View some images of upwarped mountains at this link.
Mountains formed from folding • Under certain conditions, the stress force built up by plate movement does not break the rock, but causes the crust to fold. • Caused by compression. • Folds • A bend in the rock that forms where part of Earth’s crust is compressed. • Folds vary in size from a few centimeters across to hundreds of kilometers wide.
Types of Folds • Observe figure 4 on page 107. • Two types of folds: • Anticline • An upward fold in the rock layers • Syncline • A downward fold in the rock layers. • View some images of folded mountains at this link.
How are mountains formed? • Open the link below and view the teacher tube video on How Mountains are Formed. • How are Mountains Formed?