1. Unlike catastrophism, states that mountains formed slowly over time. 2. 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 . 3. The Permian Period lasted from 299 Ma to 251 Ma. This means that the Permian Period lasted years.

uniformitarianism, Fossil groups, 48 million years ago.

Explanation:

Uniformitarianism is the doctrine of uniformity that assumes that same environmental laws and process operate till date that has also occurred on the past but not with the same uniformity. Unlike the atmospheric that is short-lived and sudden changes over the period of time. William Smith was a geologist who has noticed a certain type of fossil in a certain layer of sedimentary and igneous rock. A similar layer of strata could be found in the areas that were further apart. The Permian period was from 229 to 251 million years and was the last period of the paleozoic era and is recorded for the last major extinction in the history of life in earth and it lasted for 48 million years.