James Hutton (1726 – 1797) was a Scottish natural philosopher based in Edinburgh. He is now remembered as a geologist, although the science was not really established when he was working (indeed, he is sometimes called 'the father of geology') and he had much wider interests. He had studied medicine but never practiced, and he was a student and champion of new farming techniques.
Hutton's major contribution was arguing for a model of the world based on slow, on-going, processes. That is, rather than the then common view that the current state of the earth was the result of past catastrophes, Hutton argued that the processes in operation today (such as erosion by wind and sea) shaped the landscape over an extremely long period of time.
Hutton compared the earth to a machine (indeed, some of his idea seem similar to the Gaia hypothesis) where material was recycled. New continental material was being formed at great depth beneath the seas under conditions of high temperatures and pressure, then slowly raised up. Meanwhile rocky material was broken down to gravel and sand, and then eventually compressed into sediments. Hutton recognised that chalk was derived from animal shells and coal from plants.
Whilst some details of his theory were incorrect, his general idea of the recycling of materials powered by a source of heat deep within the earth, with the cyclic formation and breakdown of land, represented a major progression in thinking about the earth.
