Earth
Science, 10th edition
Chapter
9:
I. Deformation
A. Deformation is a general term that
refers to all changes in the original form and/or
size of a rock body
B. Most crustal deformation
occurs along plate margins
II. Folds
A. Rocks bent into a series of waves
B. Most folds result from compressional forces which shorten and thicken the crust
C. Types of folds
1. Anticline – upfolded, or arched, rock layers
2. Syncline – downfolded
rock layers
III. Faults
A. Faults are fractures (breaks) in rocks
along which appreciable displacement has taken place
B. Types of faults
1. Dip-slip fault
a. Movement along the
inclination (dip) of fault plane
b. Parts of a dip-slip fault
1. Hanging wall – the rock
above the fault surface
2. Footwall – the rock
below the fault surface
c. Types of dip-slip faults
1. Normal fault
2. Reverse and thrust
faults
2. Strike-slip faults
a. Dominant displacement is
horizontal and parallel to the trend, or strike
b. Transform fault
3. Joints
a. Fractures along which no
appreciable displacement has occurred
b. Most are formed when rocks
in the outer-most crust are deformed
A. Orogenesis
refers to processes that collectively produce a mountain belt
B. Mountain building at convergent
boundaries
1. Most mountain building occurs at
convergent plate boundaries
2. Aleutian-type mountain building
3. Andean-type mountain building
4. Continental collisions
5. Continental accretion
a. Third mechanism of mountain
building
b. Small crustal
fragments collide with and accrete to continental margins
c. Accreted crustal blocks are called terranes
d. Occurred along the