Week 10/19/12

This week in Geology we discussed many different things that i finally felt like i understood. For example, there are three different types of stress; compressive, tensional, and shear. Stress is force applied per unit area. This would be an example of each of those stresses:   
There is also multiple types of strains; elastic, yield point, plastic, and fracture.
My favorite topic of this week was folds. A part of a fold that i remember well is the fold nose or hinge fold, which is usually at the axis.  There was also two types of folds that we dicussed in full, anticline and syncline. Anticline concave downward and they are made up of older rocks. Synclines are made up of younger rocks and concave upward. Synclines make a smiley face while anticlines make an A if you draw a straight line across the downward fold.
The following picture shows an anticline to the left, a downward fold, and syncline to the right which is an upward fold.