Sharon Johnson GeoImages.Berkeley.EDU.

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

2. 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

3. 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.

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

5. 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

6. 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

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

8. Folding, Faulting and Denudation Anticline – upfolds or ridges

9. Folding, Faulting and Denudation Syncline – downfolds or valleys

10. Folding http://astro.sau.edu/~earth/html/md11.html

11. Folding, Faulting and Denudation Faults This is a transform plate boundaries, the most famous example of which is the San Andreas Fault

12. 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

13. Folding, Faulting and Denudation Normal fault – side or profile view http://salem.k12.va.us/shs/lester/ch16faulting.html

14. Folding, Faulting and Denudation Reverse fault – side or profile view http://salem.k12.va.us/shs/lester/ch16faulting.html

15. Folding, Faulting and Denudation Strike-slip fault – side and top view http://salem.k12.va.us/shs/lester/ch16faulting.html

16. 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

17. 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)

18. 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/GeoImages/Wells/geomorph/adobe.html

19. Folding, Faulting and Denudation Occasionally, differential erosion creates some interesting features Lisa Wells http://geogweb.berkeley.edu/GeoImages/Wells/geomorph/tufoni1.html

20. 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.

21. Folding, Faulting and Denudation Mechanical weathering http://www.geo.duke.edu/geo41/wea017.gif

22. Folding, Faulting and Denudation Chemical weathering Karst topography http://www.dc.peachnet.edu/~pgore/geology/geo101/weather.htm

23. 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.

24. Folding, Faulting and Denudation Talus slope at base of mountain http://maps.unomaha.edu/maher/geo117/part2/masswastingpics/Svalbardtalus.jpeg

25. 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/geography/52120/trial2/folding&.htm

26. Folding, Faulting and Denudation http://www.northernterritory.com/3-2.html

27. 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

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

29. 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

30. 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

31. Folding, Faulting and Denudation Where rivers cross the escarpment, waterfalls may be formed by undercutting.

32. Folding, Faulting and Denudation Some of these waterfalls are quite spectacular.