Figure 16.1 A marble cylinder deformed in the laboratory by applying thousands of pounds of load from above. Each sample was deformed in an environment that duplicated the confining pressure found at various depths. Notice that when the confining pressure was low, the sample deformed by brittle fracture, whereas when the confining pressure was high, the sample deformed plastically (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).

• Hooke's Law ==> elasticity

  
  
  Figure 16.2 Hooke's law.
  
  
  

Figure 16.3 Block diagram of principal types of folded strata (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).




Figure 16.4 Plunging fold interpreted into the subsurface.

• anticline vs. syncline

  
  
  Figure 16.5 Sheep Mountain - a doubly plunging anticline (NW WY). "V" s are pointing the direction of the plunges. Erosion due to the Gros Ventre River along the south flank resulted in a spectacular landslide in 1925.
  
  
  
  
  Figure 16.6 Elk Basin oil field (MT) - breached anticline.
  
  
  
  
  Figure 16.7 Dome 6 miles east of Rawlings, WY. Highway and railroad for scale.
  
  
  
  
  Figure 16.8 Folded metasediments near Macon, GA.
  
  
  
  
  Figure 16.9 Laminated gypsum - folding due to expansion of anhydrite in changing to gypsum (Castile Fm. (Permian), NM).
  
  
  
  
  Figure 16.10 Deformed quartz-muscovite-shist.
  
  
  

• symmetrical/asymmetrical, overturned, and recumbent folds

  
  
  Figure 16.11 Asymmetric anticline.
  
  
  
  
  Figure 16.12 SW plunging syncline of Precambrian metasediments (Ocoee Gorge, TN).
  
  
  
  
  Figure 16.13 Fold with drag fault along Kentucky River (KY).
  
  
  

• plunging folds, monocline

  
  
  Figure 16.14 Types of folds and their axial planes.
  
  
  
  
  Figure 16.15 Axial planes, fold axes and angles of plunge.
  
  
  
  
  Figure 16.16 River cutting through folds.
  
  
  
  
  Figure 16.17 Plunging folds. A) Idealized view. B) View after extensive erosion (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).
  
  
  
  
  Figure 16.18 Monocline consisting of folded sedimentary beds that were deformed by faulting in the bedrock below (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).
  
  
  

Figure 16.19 A) Photo of sedimentary strata sharply folded into an asymmetrical anticline and attacked by erosion. B) Drawing of this fold to illustrate the concept of strike and dip (from The Earth - An Introduction to Physical Geology (2nd ed.), by Tarbuck & Lutgens, Merrill Publishing Co., 1984).