Define structural geology, stress, and strain in rocks.

Step 1: Define Structural geology. Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. Its primary goal is to understand the forces and processes that cause deformation in the Earth's crust. Step 2: Describe stress in rocks. Stress in rocks is the force applied per unit area on a rock body. It is a measure of the intensity of the forces acting on a rock and can be compressional (squeezing), tensional (pulling apart), or shear (sliding past each other). Step 3: Describe strain in rocks. Strain in rocks is the deformation or change in shape, size, or orientation that a rock body undergoes in response to applied stress. It can manifest as changes in length, volume, or angle, leading to features like folds, faults, and fractures. That's 2 down. 3 left today — send the next one.