Part VII. Plate Tectonics II.

A. Geologic Structures (Chapter 9 in textbook).

1. Folds, fractures, and faults.

2. Form in response to stress.

3. How rocks respond to stress depends on?

4. Response to Stress = strain.

5. Types of Structures.

a. Folds

• synclines
• anticlines
  

The diagrams below are ones that I drew in class to illustrate how folding of the Earth's crust occurs:

	<-- The diagram on the left shows a pair of folds, a syncline and an anticline. Click on the image for a larger version.
Unequal stress over an area can produce plunging folds, and erosion planes off the folds exposing a pattern of lines and curves on the map view. The diagram on the right shows a pair of plunging anticlines separated by a plunging syncline. Click on the diagram for a larger version -->

b. Faults.

• Classified based on the type of movement which ultimately is controlled by the type of stress present.

The diagrams below are ones we drew in class to show how fault geometries relate to different stress regimes:

	<-- This diagram shows a block cut by NORMAL faults. What type of stress causes this type of structure? Click on the diagram for a larger view.
The diagram on the right shows a REVERSE dip slip fault. What type of stress causes this structure? Click on the picture for a larger view -->