2. Rock Deformation AKA – Mountain
Building
• Deformation - the bending, breaking, and
tilting of the earth’s crust.
• Three types of Stress:
1. Compressional
2. Tensional
3. Shear
3. FOLDING - flat layers of rock are
under severe compression and are
squeezed from the sides. The
layers moved into folded positions
without breaking (although some
cracks may appear).
4. Three types of Folds:
1. Anticlines - upward folds
2. Synclines – downward
folds
3. Monoclines – gently
dipping bends in
horizontal rock layershttp://www.cr.nps.gov/history/online_books/geology/publications/bul/1508/images/fig27.jpg
5. Features formed by tectonic activity
Normal
1. Faults - A break in the
rock layers along
which there is no
movement is called a
fracture.
Once movement
occurs, the fracture is
known as a fault.
Three Main Types of
Faults:
6. 2. Reverse Fault
• occurs along convergent boundaries (compression force)
• The hanging wall moves up above the foot wall
Thrust Fault
o reverse fault where the hanging wall is pushed at
such a low angle (not steep) that it moves UP AND
OVER the foot wall
7. 3. Strike-Slip Fault
• occurs at transform boundaries
(shearing force)
• The rocks along either side of the fault
slide horizontally
Ex. San Andreas Fault
9. Four Types of Mountains
1. Folded Mountains - Found where continents have
collided. Ex. Appalachian Mts., Himalayan Mts.
• Plateaus - areas of flat-topped land high above
sea level. Ex. Colorado Plateau (Grand Canyon)
2. Fault-Block Mountains - Formed by faults, where
part of the earth’s crust have been broken into large
blocks and then were lifted above the surrounding
crust. Ex. Grand Teton, MT
10. 3. Volcanic Mountains - Form when molten rock erupts
onto earth’s surface.
Ex. Cascade Mts. in Pacific NW and
the mid-Ocean ridges
4. Dome Mountains - An unusual type that is formed when
molten rock rises but does not break through the surface.
Ex. Adirondacks, NY
