Download Mountain Building (pg.13)

Mountain Building (pg.13)
Mountains are generally formed in one of three ways:
a) Mountains formed as result of folding.
b) Mountains formed as a result of faulting, ex: normal fault, reverse fault,
overthrust fault, block mountain, rift valley.
c) Mountains formed as a result of volcanic activity, ex: ash and cinder cone,
composite cone, shield cone.
a) Mountains formed through folding:
1. Most major mountain ranges were formed by folding. Explain this process. As well,
include a sketch of this process with directional arrows indicating plate movement
and labels indicating the ANTICLINE and SYNCLINE sections of the mountains.
2. At which type of tectonic zone would you find folded mountains? (ridge or
subduction, see fig. 1.10, pg 12)
b) Mountains formed as a result of faulting: fault lines are great cracks in the crust. Draw arrows
to indicate the movement of the plates in each example.
a) Mountains Formed by Normal Faults: Normal Faults are caused by tensional
forces. When the land moves apart at a fault line one plate drops down lower that the
other.
b) Mountains Formed by Reverse Faults: Reverse faults are caused by compressional
forces where plates move together at the fault. This movement causes one plate rises
above another. The land that rises above can form a mountain.
c) Fault Block Mountains: Fault Block Mountains sometimes form when many layers
of the Earth's crust are moved vertically upward between two parallel fault lines.
Vertical force is caused by the earth's internal pressure. The mountains that are
formed in this way are called fault-block mountains. The Sierra Nevada mountains in
California and Nevada, and the Grand Teton range of Wyoming are examples of
fault-block mountains.
d) Overthrust Faults: Overthrust Faults are created in the same manner as reverse
faults, however, they have had folding occur before the fault and movement occured.
e) Rift Valley: created when two faults occur parallel to each other; the broken plate
between them drops down as the broken plates move away from each other.