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

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. Sharon Johnson http://GeoImages.Berkeley.EDU.
Folding, Faulting and Denudation
This unit will examine the “balance” between some localized forces – folding, faulting and denudation (levelling of the surface)
Sharon Johnson

4. Folding, Faulting and Denudation
Tectonic activity is an “earth-building” activity
Sharon Johnson

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

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)

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

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

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

10. Folding

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:

13. Folding, Faulting and Denudation
Normal fault – side or profile view

14. Folding, Faulting and Denudation
Reverse fault – side or profile view

15. Folding, Faulting and Denudation
Strike-slip fault – side and top view

16. Folding, Faulting and Denudation
Where a block of earth rides up or down between two parallel fractures we see grabens and horsts

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

19. Occasionally, differential erosion creates some interesting features
Folding, Faulting and Denudation
Occasionally, differential erosion creates some interesting features
Lisa Wells

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

22. Folding, Faulting and Denudation
Chemical weathering
Karst topography

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

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)

26. Folding, Faulting and Denudation
                                                                                   

27. Folding, Faulting and Denudation
In Ontario, the Niagara Escarpment has been formed by differential erosion.

28. Folding, Faulting and Denudation

29. Folding, Faulting and Denudation
The escarpment is the exposed edge of a large scale syncline (geosyncline).

30. Folding, Faulting and Denudation
The escarpment is the exposed edge of a large scale syncline (geosyncline).

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

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