**2. Rocks and geological structures**

Geologic structures are usually the result of the powerful tectonic forces that occur within the earth. These forces fold and break rocks, form deep faults, and build mountains. Repeated applications of force can create a very complex geologic picture that is difficult to interpret.

### **2.1 Rock types**

Types of rocks are igneous, sedimentary and metamorphic. Igneous rocks are formed when molten rocks cools and solidifies. Sedimentary rocks arise when

particles settle down out of water or air, or by precipitation of minerals from the water. Pile up in layers. Metamorphic rocks result when existing rocks are altered by heat, pressure, or reactive fluids, such as hot water rich in minerals [3].
