As present processes are thought to explain all past events, the Uniformitarian slogan is the present is the key to the past. Uniformitarianism is a key principle of geology. My research will explain the theory of uniformitarianism and the work of many geologists such as Charles Lyell and James Hutton. To begin, one needs to understand that no serious scientific discussion of any topic should include supernatural explanations, since the basic assumption of science is that the world can be explained entirely in physical terms.
Uniformitarianism was formulated by Scottish naturalists in the late 18th century, beginning with the work of the geologist James Hutton, which was refined by John Playfair and popularized by Charles Lyells Principles of Geology in 1830. In 1785 James Hutton proposed an opposing, infinite cycle based on natural history and not on the Biblical record. The solid parts of the present land on earth appear to have been made up of the productions of the sea, and of other materials similar to those now found upon shores.
Hence we find reason to conclude first, that the land we live on is not simple and original, but that it is a composition, and had been formed by the operation of second causes. Secondly, that before the present land was made, there had been a world composed of sea and land that had tides and currents, which still take place now at the bottom of the sea. And lastly, that while the current land was forming at the bottom of the ocean, the land before had plants and animals; at least the sea was then inhabited by animals, in a similar way as it is now.
Hutton then sought evidence to support his idea that there must have been repeated cycles, each involving deposition on the sea floor, up lifting with tilting and erosion, and moving under the sea again for more layers to be deposited. In the spring of 1788 he took a boat trip along the Berkwickshire coast with Playfair and another geologist named James Hall. Playfair later recalled that the mind seemed to grow giddy by looking so far into the abyss of time, and Hutton concluded a paper he presented at the Royal Society of Edinburgh with the phrase we find no vestige of a beginning, no prospect of an end.
From 1830 to 1833 Charles Lyells multi-volume Principles of Geology was published. The books subtitle was An attempt to explain the former changes of the Earths surface by reference to causes now in operation. In the book he stated that most of Earths structural features could be explained as the result of constantly occurring processes over millions of years, further developing Huttons idea. He drew his explanations from field studies conducted right before he went to work on the book.
The terms uniformitarianism for this idea, and catastrophism for the opposing idea, were coined by William Whewell in a review of Lyells book. Principles of Geology was said to be the most influential geological work in the middle of the 19th century, and Lyell is acclaimed as the father of modern geology. Lyell influenced Charles Darwin, who later wrote The Origin of Species in 1859. Lyell supported his theory by analyzing the long-term effect of observations in a way similar to Hutton, such as the erosion of land by rivers.
In Lyells time, most scientists still believed Earth had been shaped by rare and sudden events that were unique to the past, so convincing people of his time was extremely difficult. Other scientists had opinions on the theory of Uniformitarianism as well. In 1963, a geologist named Reijer Hookyas decided to even further analyze Lyells work. According to Hookyas, Lyells uniformitarianism is a family of four related propositions, not a single idea. None of these connotations requires another, and they are not all equally inferred by uniformitarianism.
The four related propositions are: Uniformity of Law The laws of nature are constant across time and space. Uniformity of Methodology The appropriate hypothesis for explaining the geological past are those with analogy today. Uniformity of Kind Past and present causes are all of the same kind, have the same energy, and produce the same effects. Uniformity of Degree Geological circumstances have remained the same over time. Stephen Jay Goulds first scientific paper, Is uniformitarianism necessary? which was published in 1965, reduced these four interpretations to two, methodological and substantive uniformitarianism.
Uniformitarianism was originally proposed in contrast to catastrophism, which states that the distant past consisted of epochs of paroxysmal and catastrophic action interposed between periods of comparative tranquility. (Whewell 103-123). Especially in the late 19th and early 20th centuries, most geologists took this interpretation to mean that catastrophic events are not important in geologic time; one example of this is the debate of the formation of the Channeled Scablands due to the catastrophic Missoula glacial outburst floods.
An important result of this debate and others was the re-clarification that, while the same principles operate in geologic time, catastrophic events that arent frequent on human time-scales can have important consequences in geologic history. Derek Ager noted that geologists do not deny uniformitarianism in its true sense, that is to say, of interpreting the past by means of the processes that are seen going on at the present day, so long as we remember that the periodic catastrophe is one of those processes. Those periodic catastrophes make more showing in the stratigraphical record than we have hitherto assumed. Even Charles Lyell thought that ordinary geological processes would cause Niagara Falls to move upstream to Lake Erie within 10,000 years, leading to catastrophic flooding of a large part of North America. Unlike Lyell, modern geologists do not apply uniformitarianism in the same way. They question if rates of processes were uniform through time and only those values measured during the history of geology are to be accepted. (Matthews, 16-18). The present may not be a long enough key to unlock the deep lock of the past.
Geologic processes may have been active at different rates in the past that humans have not observed. According to Gary A. Smith, By force of popularity, uniformity of rate has persisted to our present day. For more than a century, Lyells rhetoric conflating axiom with hypotheses has descended in unmodified form. Many geologists have been stifled by the belief that proper methodology includes an a priori commitment to gradual change, and by a preference for explaining large-scale phenomena as the concatenation of innumerable tiny changes. The current hypothesis is that Earths history is a slow, gradual process punctured by occasional natural catastrophic events that have affected Earth and the people who inhabit it. In practice it is reduced from Lyells theory to simply the two philosophical assumptions. This is also known as the principle of geological actualism, which states that all past geological action was like all present geological action. The principle of actualism is the cornerstone of paleoecology.