Rock Deformation Basics
Ever wonder how mountains form? It all starts with stress—forces that push, pull, or twist rocks. There are three main types: compressional (pushing together), tensional (pulling apart), and shear (forces moving in opposite directions).
When rocks experience stress, they respond with strain—actual changes to their shape. How a rock responds depends on its strength, temperature, and pressure conditions. Some rocks might temporarily change shape (elastic strain), while others bend permanently (plastic/ductile strain) or completely break (brittle strain).
Geologists study rock structures using strike and dip measurements. Strike tells us the direction a rock layer travels horizontally, while dip indicates the direction and angle the layer tilts downward—kind of like describing which way a roof slants and how steep it is.
Quick Tip: Think of strike and dip like a book on a table. Strike is the direction along the spine, and dip is which way and how much the book is tilted.
