Question

What is uniformitarianism?

Answer 1

Hint: Uniformitarianism is a theory developed by Charles Lyell and James Hutton in the field of geology. This theory is the foundation on which the advancements in the science of geology can be done.

Complete answer:
Like every revolutionary scientific break-through during the olden times, uniformitarianism was also resisted greatly by the people of the $18^{th}$ century when James Hutton first presented his idea in Theory of the Earth (1795). The theory for the origins of Earth before James Hutton was widely accepted. People believed that the planet we live on was created by some supernatural phenomenon.
When uniformitarianism was introduced, which proved that rocks alone could explain the formation of Earth by studying the geological processes that operate till date, believers of the supernatural theory opposed. Uniformitarianism suggested that the present is the key to the past.
The theory shows that the Earth’s history can be understood by looking at the geological changes we observe today, like earthquakes, weathering of rocks, sedimentation, formation of soil, etc. James Hutton also stated that supernatural causes had nothing to do with the formation of Earth.
In 1830-33, Scottish geologist Sir Charles Lyell, gave evidence supporting Hutton’s theory, which was supported by Charles Darwin. Later in the $19^{th}$ century, William Thompson pointed out that due to thermal conduction, Earth loses heat and this heat loss could be the reason for the geological changes stated in theories by Hutton, Lyell and Darwin’s Origin of Species.

Note:
Though the theory states that geological processes have been the same over time but due to radioactive decay of Uranium and Thorium present in the Earth’s crust, its temperature has changed leading to change in igneous activity and movement of crust. This contradicts the theory as the phenomenon that caused deformation billions of years ago may have been different due to a hotter Earth’s crust.