The earth science which deals with the solid earth, the rocks of which the solid earth is made up of, and the processes which are involved in their change is called geology. Along with Earth, geology also deals with the solid features of other planets and natural satellites. There are various methods which are used in geology such as geophysical techniques, numerical modeling, rock description and chemical analysis. Some of the practical applications of this field are providing insights into past climate change, evaluating water resources, remediating environmental problems, and mineral and hydrocarbon exploration. Geology is also involved in the dating of different rocks and fossils. The methods which are used for dating are broadly divided into two types, namely, relative dating and absolute dating. This book discusses the fundamentals as well as modern approaches of geology. It consists of contributions made by international experts. The book will serve as a valuable source of reference for graduate and post graduate students.