Hydrogeology is a branch of geology, the study of rocks and the structures that are formed over past periods of time. The way that sediments have been deposited to create different layers of rock beneath the surface, or the way that rocks have been heated and folded over millions of years to create complex structures are the subjects of geology. Hydrogeology looks at how water interacts with geological systems. But there is more to hydrogeology than wet rocks. Water is a vital natural resource for people all around the world - whether it is piped to homes or drawn out of wells. Understanding where it is and how it moves under the ground is essential in protecting this resource.