HUTTON, JAMES (b. Edinburgh, Scotland, 3 June 1726; d. Edinburgh, 26 March 1797), geology, agriculture, physical sciences, philosophy.

Interest in various branches of the earth sciences was then widespread, but recognition of geology as an individual science had scarcely begun. The mining of economic minerals was one of the oldest industries, but the development of scientific mineralogy was retarded by the undeveloped state of chemistry and crystallography. Nevertheless, through mining and quarrying operations, a knowledge of stratigraphy must have been acquired locally, but it remained rudimentary because of the almost universal belief that the fossiliferous sediments had been deposited by, or during the retreat of, the Noachian flood. While fossils themselves had long aroused interest (it was recognized that some forms could not be matched by known living species) their value as chronological and stratigraphic indexes had not yet been recognized except, perhaps, over very limited local stratigraphic ranges.

Crystalline rocks such as granite and gneiss, usually found in the core of mountain ranges, were regarded as primeval in age, and the sediments, often fossiliferous, on the flanks of the mountains and in low ground were assumed to be flood deposits. This classification carried no implication that any rocks were older than the five or six thousand years allowed for in biblical chronology. By about the middle of the eighteenth century, however, one or two authors had suggested that geological time might be longer than this chronology allowed. The effects of erosion, long recognized, formed a subject for debate over whether denudation would ultimately render the earth uninhabitable, or whether it would be compensated by the elevation of new lands on which life would continue.

There existed one major gap in geological knowledge. It was unsuspected that rocks of the type now classed as igneous formed a major and widely distributed rock group, wholly distinct in origin from the sediments. The extrusion of lava from active volcanoes was looked on as a local and superficial phenomenon. After about 1740, Italian and French naturalists recognized the existence, locally, of volcanic cones and lava flows in areas where there was no record of volcanic activity in historic times; but many years passed before it was realized that volcanic activity had been worldwide, not only in historic times but in past geologic ages. The igneous origin of many rocks interbedded in, or otherwise closely associated with, the sediments was still unrecognized.

Broadly speaking, the position was that many geological observations had been made and recorded in the literature; but previous attempts to synthesize these observations into a general “theory of the earth” were unscientific and had not proved acceptable. The issue had been confused and progress retarded by a literal belief in the biblical account of creation and the universal flood.

The Theory of the Earth.

Hutton's theory, or “System of the Earth,” as he called it originally, was first made public at two meetings of the Royal Society of Edinburgh, early in 1785. The society published it in full in 1788, but offprints of this paper were in circulation in 1787, and possibly in 1786. The theory first appeared in print in condensed form, in a thirtypage pamphlet entitled Abstract of a Dissertation ... Concerning the System of the Earth, Its Duration, and Stability, which Hutton circulated privately in 1785. The interest of this pamphlet is that it states all the conclusions which were essential to the theory as a whole. It emphasizes that even at this early date Hutton's thinking was far ahead of that of his contemporaries. For this reason, and because it is more easily comprehended than the full version, it is summarized here.

Hutton's approach in the Abstract is logical, but his thought is not translated into clear and incisive prose. As with almost all that he wrote (other than private letters), his style is prolix and abstruse, so that the text must be read with care to appreciate its full significance.

Hutton describes briefly his purpose in carrying out the inquiry, the methods he employed in reaching his conclusions, and the conclusions themselves. His purpose was to ascertain (a) the length of time the earth had existed as a “habitable world”; (b) the changes it had undergone in the past; and (c) whether any end to the present state of affairs could be foreseen. He stated that the facts of the history of the earth were to be found in “natural history,” not in human records, and he ignored the biblical account of creation as a source of scientific information (a view he expressed explicitly later on). The method he employed in carrying out his inquiry had been a careful examination of the rocks of the earth's crust, and a study of the natural processes that operated on the earth's surface, or might be supposed, from his examination of the rocks, to have operated in the past. In this way, “from principles of natural philosophy,” he attempted to arrive at some knowledge of the order and system in the economy of the globe, and to form a rational opinion as to the course of nature and the possible course of natural events in the future.

Hutton concluded that rocks in general (clearly he referred here to the sedimentary rocks) are composed of the products of the sea (fossils) and of other materials similar to those found on the seashore (the products of erosion). Hence they could not have formed