1. FOLDS and FAULTS Stresses in the Earth’s Crust

2. Stress can be Compressional, Tensional, or Shear Compressional stress pushes matter (rock layers) together Tensional stress pulls matter (rock and dirt layers) apart. Shear stress is rotational, the stress is parallel to a face of the material

3. 2 Basic Types of Folds 1- Anticline: when layers are folded upwards in what looks like an arch. The layers are symmetrical (look alike) on either side of its center. Caused by Compressional Stresses

4. 2 Basic Types of Folds 2- Syncline This is when the rock layers are folded downward. Caused by Compressional Stresses

5. A Third Type of Fold Overturned Folds: anticlines and /or synclines that have also undergone secondary forces Caused by Compressional Stresses followed by Shear Stresses, or Compressional Stresses from a different direction from the original force.

6. FRACTURES and FAULTS Breaks in rock are put into two categories • Fractures: When there is no movement along either side of the rock break. • Faults: When either side of the rock break moves in opposite directions

7. 3 Types of Faults 1- Normal Fault:One side of the fault has slipped down in comparison to the other side. Normal Faults are caused by layers being pulled apart, by TENSIONAL stresses. Gravity causes one side to slip down.

8. 3 Types of Faults 2- Reverse Fault: One side of the fault has slipped up in comparison to the other. When layers are pushed together, by COMPRESSIONAL forces, this kind of fault occurs. stress

9. 3 Types of Faults 3- Lateral or Strike-Slip Fault: Two layers of rock are shifted horizontally or parallel to the fault plane. These faults are created by SHEAR forces Images from: http://www.williamsclass.com/SixthScienceWork/FoldFault/FoldFaultGeologyNotes.htm#Fault