Unlike catastrophism, states that mountains formed slowly over time. William Smith was working as a surveyor in the late eighteenth century. He noticed that certain fossils were found in certain layers of sedimentary or igneous rock, that the same order of strata could be found in areas that were far apart, and these strata contained similar .
The Permian Period lasted from 299 Ma to 251 Ma. This means that the Permian Period lasted years.