Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth's Surface, by Reference to Causes Now in Operation is a book by the Scottish geologist Charles Lyell that was first published in 3 volumes from 1830 to 1833. Lyell used the theory of uniformitarianism to describe how the Earth's surface was changing over time.[3] This theory was in direct contrast to the geological theory of catastrophism.[3]
Many individuals believed in catastrophism to allow room for religious beliefs. For example, the Genesis flood narrative could be described as a real geological event as catastrophism describes the changing of the Earth surface as one-time, violent events.[3] Lyell challenged the believers of the catastrophic theory by studying Mount Etna in Sicily and describing the changes from one stratum to another and the fossil records within the rocks to prove that slow, gradual changes were the cause of the ever-changing Earth's surface.[3] Lyell used geological evidence to determine that the Earth was older than 6,000 years, as had been previously contested. The book shows that the processes that are occurring in the present are the same processes that occurred in the past.[4]