ABSTRACT

Gradualism is a school of thought arguing that, throughout the history of the Earth, geological and biological processes have operated at rates more or less the same as those observed in the present day. Most commentators credit James Hutton (1726-97) as the father of gradualism. Admittedly, well before Hutton, Aristotle and Leonardo da Vinci discussed the effectiveness of geological agencies – wind, rain, sea, sun, and earthquakes – in refashioning the Earth’s surface, but Hutton was assuredly the architect of the first full-blown gradualist system of Earth history. He saw the world as a perfect machine that would run forever through its cycles of decay and repair – crustal uplift, erosion, transport, deposition, compaction and consolidation, and renewed uplift – now called the geological or sedimentary cycle. John Playfair (1748-1819) energetically championed Hutton’s revolutionary ideas; Charles Lyell (1797-1875), in his celebrated Principles of Geology (1830-33), embellished and elaborated upon them. Lyell, the arch gradualist, carefully and convincingly argued that the slow and steady operation of present geological processes could explain the apparently enormous changes that the Earth had evidently suffered in the past. Gradualism was an essential ingredient of Lyell’s uniformitarianism that pervaded thinking in the Earth and life sciences until catastrophism made its recent comeback.