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									Folding, Faulting and Denudation




                      Sharon Johnson
             http://GeoImages.Berkeley.EDU.
Folding, Faulting and Denudation


                    Forces in Balance


   Some forces build up the earth – e.g. plate tectonics,
           volcanoes and folding and faulting.
  Other forces tear down that which is built – e.g. rivers,
                 glaciers and weathering
Folding, Faulting and Denudation

    This unit will examine the
     “balance” between some
    localized forces – folding,
      faulting and denudation
     (levelling of the surface)




                              Sharon Johnson
                     http://GeoImages.Berkeley.EDU.
Folding, Faulting and Denudation
     Tectonic activity is an “earth-building” activity




                               Sharon Johnson
                      http://GeoImages.Berkeley.EDU.
Folding, Faulting and Denudation
   Folding is the process that bends and twists rocks,
               usually due to compression
  Faulting is the process where rocks move past each
                  other along a fracture




                    http://www.geog.ouc.bc.ca/physgeog/
                             contents/10l.html
Folding, Faulting and Denudation
   Volcanism is the term
   used to describe the
   movement of molten
  rock beneath or above
     the earth’s surface
    (covered in another
            unit)




                    http://volcano.und.nodak.edu/vwdocs
                       /volc_images/img_arenal1.html
Folding, Faulting and Denudation

Folds
Occur when
compressional
forces cause
rock layers to
bend
Folding, Faulting and Denudation

             Anticline – upfolds or ridges
Folding, Faulting and Denudation

           Syncline – downfolds or valleys
Folding




          http://astro.sau.edu/~earth/html/md11
                            .html
Folding, Faulting and Denudation

           Faults
      In the unit on plate
   tectonics you discovered
  the existence of transform
  plate boundaries, the most
 famous example of which is
    the San Andreas Fault
Folding, Faulting and Denudation
 On a smaller scale there are a number of other types of
faults, categorized by the relative motion of the blocks of
                          earth:




                    http://astro.sau.edu/~earth/html/md11
                                      .html
Folding, Faulting and Denudation
Normal fault – side or profile view




                     http://salem.k12.va.us/shs/lester/ch16
                                  faulting.html
Folding, Faulting and Denudation
 Reverse fault – side or profile view




                      http://salem.k12.va.us/shs/lester/ch16
                                   faulting.html
Folding, Faulting and Denudation
 Strike-slip fault – side and top view




                       http://salem.k12.va.us/shs/lester/ch16
                                    faulting.html
Folding, Faulting and Denudation
  Where a block of earth rides up or down between two
     parallel fractures we see grabens and horsts




                   http://astro.sau.edu/~earth/html/md11
                                     .html
Folding, Faulting and Denudation

Denudation – processes which tend to level the earth’s
surface.


Consists of two broad categories :
•degradation (weathering, erosion and transportation)
•aggradation (deposition)
Folding, Faulting and Denudation
   Once new landforms are created by tectonic forces,
weathering and erosion begin to wear away at those forms.
     The overall effect is a “softening” of landscapes.




                                Lisa Wells
                   http://geogweb.berkeley.edu/GeoIma
                     ges/Wells/geomorph/adobe.html
Folding, Faulting and Denudation
    Occasionally, differential erosion creates some
                  interesting features




                                Lisa Wells
                   http://geogweb.berkeley.edu/GeoIma
                     ges/Wells/geomorph/tufoni1.html
Folding, Faulting and Denudation


 Chemical weathering involves a chemical change in at
 least some of the minerals within a rock.
 Mechanical weathering involves physically breaking
 rocks into fragments without changing the chemical
 make-up of the minerals within it.
Folding, Faulting and Denudation
 Mechanical weathering




                 http://www.geo.duke.edu/geo41/wea0
                                17.gif
Folding, Faulting and Denudation


Chemical
weathering
Karst topography




                   http://www.dc.peachnet.edu/~pgore/g
                        eology/geo101/weather.htm
Folding, Faulting and Denudation
 As soon as a rock particle (loosened by one of the two
 weathering processes) moves, we call it erosion or
 mass wasting. Mass wasting is simply movement down
 slope due to gravity. Rock falls, slumps, and debris
 flows are all examples of mass wasting. We call it
 erosion if the rock particle is moved by some flowing
 agent such as air, water or ice.
Folding, Faulting and Denudation
 Talus slope at
 base of
 mountain




                  http://maps.unomaha.edu/maher/geo1
                  17/part2/masswastingpics/Svalbardtal
                                 us.jpeg
Folding, Faulting and Denudation
  Consider this famous landform feature resulting from a
resistant layer of rock appearing at the surface, surrounded
                by softer rocks. (Ayers Rock)




                    www.ahs.cqu.edu.au/humanities/geog
                     raphy/52120/trial2/folding&.htm
Folding, Faulting and Denudation




                http://www.northernterritory.com/3-
                             2.html
Folding, Faulting and Denudation
 In Ontario, the Niagara Escarpment has been formed by
                    differential erosion.




                             http://www4.vc-
                    net.ne.jp/~klivo/gen/geology.htm
Folding, Faulting and Denudation




                          http://www4.vc-
                 net.ne.jp/~klivo/gen/geology.htm
Folding, Faulting and Denudation
  The escarpment is the exposed edge of a large scale
               syncline (geosyncline).




                             http://www4.vc-
                    net.ne.jp/~klivo/gen/nmapeng.gif
Folding, Faulting and Denudation
  The escarpment is the exposed edge of a large scale
               syncline (geosyncline).




                             http://www4.vc-
                    net.ne.jp/~klivo/gen/geology.htm
Folding, Faulting and Denudation
  Where rivers cross the escarpment, waterfalls may be
                 formed by undercutting.
Folding, Faulting and Denudation
     Some of these waterfalls are quite spectacular.

								
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