Hutton was the son of a merchant and city officeholder. Though Hutton’s father died when his son was quite young, Hutton managed an education in the local grammar school and at the University of Edinburgh. Although already interested in chemistry, he entered the legal profession. But as a lawyer’s apprentice, he is said to have devoted more time to amusing his fellow clerks with chemical experiments than to copying legal documents. He, along with his friend James Davie, was also deeply interested in investigating the manufacture of sal ammoniac from coal soot. As a result, he was released from law apprenticeship before his first year was out, and he turned to the study of medicine, as it was most closely related to chemistry. He spent three years at the University of Edinburgh, then two in Paris, and finally was granted an M.D. degree in Holland in September 1749.
But medicine held small appeal for Hutton. His association with Davie in developing an inexpensive method for the manufacture of sal ammoniac proved financially rewarding, and so Hutton decided to take up farming in Berwickshire, Scotland. By 1765 both the farm and the company producing sal ammoniac were prospering, and with a good income available, he gave up farming in 1768 to establish himself in Edinburgh, where he could pursue his scientific interests.Hutton devoted his time to extensive scientific reading and traveled widely to inspect rocks and observe the actions of natural processes. His chief contribution to scientific knowledge, the uniformitarian principle, was put forward in his papers presented to the Royal Society of Edinburgh in 1785. Two of these papers were published in 1788 in the Transactions of the Royal Society of Edinburgh under the title “Theory of the Earth; or an Investigation of the Laws Observable in the Composition, Dissolution, and Restoration of Land Upon the Globe.”Hutton’s view as stated in these papers was that the world’s geologic phenomena can be explained in terms of observable processes, and that those processes now at work on and within the Earth have operated with general uniformity over immensely long periods of time. These two papers marked a turning point for geology; from that time on, geology became a science founded upon the principle of uniformitarianism.
Hutton’s ideas were astonishing when viewed in the context of the opinion of his day. By the late 18th century, much knowledge had been gained about rocks, strata, and fossils, but none of this wealth of data had been synthesized into a workable general theory of geology. Such a task was seriously impeded by the still-accepted belief that the Earth had been created only about 6,000 years ago, according to the narrative in the biblical book of Genesis. The world’s sedimentary rocks were believed by some geologists to have been formed when immense quantities of minerals precipitated out of the waters of the biblical flood. Erosional processes had long been recognized, but there was no equivalent explanation for the creation of land surfaces, as opposed to their destruction by erosion. The significance of rock formation by means of volcanism and other heat-generated processes in the Earth’s crust was almost completely unrecognized, as was the existence of igneous rocks in general.
Hutton’s ideas were diametrically opposed to much of this contemporary theory. He asserted that many rocks had indeed been formed by sedimentary processes—i.e., that rock particles had been washed off the land into the oceans, had accumulated in beds there, and had solidified into rocks. But he posited that the solidification into rocks was due not to the particles’ simple precipitation out of a watery solution but rather was due to the effects of pressure and heat, an explanation which stands to the present day. Hutton asserted that the wearing down of land surfaces by erosion was countered by the formation of new land surfaces due to volcanism and other processes in which the internal heat of the Earth brought new rock constitutents up to the Earth’s surface. These new mountains and other landforms were then in turn eroded and were deposited as sediments in the sea, from which they could be upthrust into new land surfaces by subterranean heat-generated processes.
Hutton claimed that the totality of these geologic processes could fully explain the current landforms all over the world, and no biblical explanations were necessary in this regard. Finally, he stated that the processes of erosion, deposition, sedimentation, and upthrusting were cyclical and must have been repeated many times in the Earth’s history. Given the enormous spans of time taken by such cycles, Hutton asserted that the age of the Earth must be inconceivably great.
Hutton summarized his views and provided ample observational evidence for his conclusions in a work published in two volumes, Theory of the Earth, in 1795. A third volume was partly finished at the time of Hutton’s death.
Although Hutton’s ideas received a fairly wide circulation among European scientists, their immediate impact was blunted by the fact that Hutton’s writing style was difficult to understand. Fortunately, his close friend John Playfair wrote a clear and precise condensation of Hutton’s work, embellished with additional observations of his own, and published it in 1802 under the title Illustrations of the Huttonian Theory of the Earth. It went far toward establishing the correctness of uniformitarianism, the cornerstone on which the science of geology is erected.
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