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Uniformitarianism (science)
Encyclopedia
In the philosophy of naturalism
, the uniformitarianism assumption is that the same natural laws and processes that operate in the universe
now, have always operated in the universe in the past and apply everywhere in the universe. It has included the gradualistic
concept that "the present is the key to the past" and is functioning at the same rates. Uniformitarianism has been a key principle of geology, but naturalism's modern geologists, while accepting that geology has occurred across deep time, no longer hold to a strict gradualism.
Uniformitarianism was formulated by Scottish naturalists
in the late 18th century, starting with the work of the geologist
James Hutton
, which was refined by John Playfair
and popularised by Charles Lyell
's Principles of Geology in 1830. The term uniformitarianism was coined by William Whewell
, who also coined the term catastrophism
for the idea that the Earth was shaped by a series of sudden, short-lived, violent events.
The earlier conceptions likely had little influence on 18th century European geological explanations for the formation of the Earth. Abraham Gottlob Werner
proposed Neptunism
where strata
were deposits from shrinking seas precipitated
onto primordial rocks such as granite
. In 1785 James Hutton
proposed an opposing, self-maintaining infinite cycle based on natural history and not on the Biblical record.
Hutton then sought evidence to support his idea that there must have been repeated cycles, each involving deposition on the seabed
, uplift with tilting and erosion
, and then moving undersea again for further layers to be deposited. At Glen Tilt
in the Cairngorm mountains
he found granite penetrating metamorphic
schist
s, in a way which indicated to him that the presumed primordial rock had been molten
after the strata had formed. He had read about angular unconformities
as interpreted by Neptunists, and found an unconformity
at Jedburgh
where layers of greywacke
in the lower layers of the cliff face have been tilted almost vertically before being eroded to form a level plane, under horizontal layers of Old Red Sandstone
. In the Spring of 1788 he took a boat trip along the Berwickshire
coast with John Playfair
and the geologist Sir James Hall, and found a dramatic unconformity showing the same sequence at Siccar Point
. Playfair later recalled that "the mind seemed to grow giddy by looking so far into the abyss of time", and Hutton concluded a 1788 paper he presented at the Royal Society of Edinburgh
, later rewritten as a book, with the phrase "we find no vestige of a beginning, no prospect of an end."
Both Playfair and Hall wrote their own books on the theory, and for decades there was a robust debate between Hutton's supporters and the Neptunists. Georges Cuvier
's paleontological work
in the 1790s, which established the reality of extinction
, explained this by local catastrophes, after which other fixed species repopulated the affected areas. In Britain, geologists adapted this idea into "diluvial theory
" which proposed repeated worldwide annihilation and creation of new fixed species adapted to a changed environment, initially identifying the most recent catastrophe as the biblical flood.
's multi-volume Principles of Geology
was published. The work's subtitle was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation". He drew his explanations from field studies conducted directly before he went to work on the founding geology text, and developed Hutton's idea that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. The terms uniformitarianism for this idea, and catastrophism
for the opposing viewpoint, were coined by William Whewell
in a review of Lyell's book. Principles of Geology was the most influential geological work in the middle of the 19th century.
(1963), Lyell's 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 uniformitarians.
Gould
expounded on similar propositions in Time's Arrow, Time's Cycle
(1987), stating that Lyell conflated two different types of propositions: a pair of methodological assumptions with a pair of substantive hypotheses. The four together make up Lyell's uniformitarianism.
Methodological assumptions
The two methodological assumptions are universally acclaimed by scientists, and embraced by all geologists. Gould further states that these philosophical propositions must be assumed before you can proceed as a scientist doing science. "You cannot go to a rocky outcrop and observe either the constancy of nature's laws or the working of unknown processes. It works the other way around." You first assume these propositions and "then you go to the out crop of rock."
Substantive hypotheses
The substantive hypotheses were controversial and, in some cases, accepted by few. These hypotheses are judged true or false on empirical grounds through scientific observation and repeated experimental data. This is in contrast with the previous two philosophical assumptions that come before one can do science and so cannot be tested or falsified by science.
's first scientific paper, Is uniformitarianism necessary? (1965), reduced these four interpretations to two, methodological and substantive uniformitarianism. He dismissed the first principle, which asserted spatial and temporal invariance of natural laws, as no longer an issue of debate. He rejected the second as an unjustified limitation on scientific inquiry, as it constrains past geologic rates and conditions to those of the present. So, uniformitarianism was unnecessary.
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" 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 are infrequent on human time-scales can have important consequences in geologic history.
Derek Ager has 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. The present may not be a long enough key to penetrate the deep lock of the past. Geologic processes may have been active at different rates in the past that humans have not observed. “By force of popularity, uniformity of rate has persisted to our present day. For more than a century, Lyell’s 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 consensus is that Earth's history
is a slow, gradual process punctuated by occasional natural catastrophic events that have affected Earth and its inhabitants. In practice it is reduced from Lyell's conflation 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
.
Metaphysical naturalism
Metaphysical naturalism, also called ontological naturalism and philosophical naturalism, or just naturalism, is a philosophical worldview and belief system that holds that there is nothing but natural elements, principles, and relations of the kind studied by the natural sciences, i.e., those...
, the uniformitarianism assumption is that the same natural laws and processes that operate in the universe
Universe
The Universe is commonly defined as the totality of everything that exists, including all matter and energy, the planets, stars, galaxies, and the contents of intergalactic space. Definitions and usage vary and similar terms include the cosmos, the world and nature...
now, have always operated in the universe in the past and apply everywhere in the universe. It has included the gradualistic
Gradualism
Gradualism is the belief in or the policy of advancing toward a goal by gradual, often slow stages.-Politics and society:In politics, the concept of gradualism is used to describe the belief that change ought to be brought about in small, discrete increments rather than in abrupt strokes such as...
concept that "the present is the key to the past" and is functioning at the same rates. Uniformitarianism has been a key principle of geology, but naturalism's modern geologists, while accepting that geology has occurred across deep time, no longer hold to a strict gradualism.
Uniformitarianism was formulated by Scottish naturalists
Natural history
Natural history is the scientific research of plants or animals, leaning more towards observational rather than experimental methods of study, and encompasses more research published in magazines than in academic journals. Grouped among the natural sciences, natural history is the systematic study...
in the late 18th century, starting with the work of the geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
James Hutton
James Hutton
James Hutton was a Scottish physician, geologist, naturalist, chemical manufacturer and experimental agriculturalist. He is considered the father of modern geology...
, which was refined by John Playfair
John Playfair
John Playfair FRSE, FRS was a Scottish scientist and mathematician, and a professor of natural philosophy at the University of Edinburgh. He is perhaps best known for his book Illustrations of the Huttonian Theory of the Earth , which summarized the work of James Hutton...
and popularised by Charles Lyell
Charles Lyell
Sir Charles Lyell, 1st Baronet, Kt FRS was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by slow-moving forces still in operation...
's Principles of Geology in 1830. The term uniformitarianism was coined by William Whewell
William Whewell
William Whewell was an English polymath, scientist, Anglican priest, philosopher, theologian, and historian of science. He was Master of Trinity College, Cambridge.-Life and career:Whewell was born in Lancaster...
, who also coined the term catastrophism
Catastrophism
Catastrophism is the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope. The dominant paradigm of modern geology is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
for the idea that the Earth was shaped by a series of sudden, short-lived, violent events.
18th century
Abraham Gottlob Werner
Abraham Gottlob Werner , was a German geologist who set out an early theory about the stratification of the Earth's crust and coined the word Neptunism...
proposed Neptunism
Neptunism
Neptunism is a discredited and obsolete scientific theory of geology proposed by Abraham Gottlob Werner in the late 18th century that proposed rocks formed from the crystallisation of minerals in the early Earth's oceans....
where strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
were deposits from shrinking seas precipitated
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
onto primordial rocks such as granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
. In 1785 James Hutton
James Hutton
James Hutton was a Scottish physician, geologist, naturalist, chemical manufacturer and experimental agriculturalist. He is considered the father of modern geology...
proposed an opposing, self-maintaining infinite cycle based on natural history and not on the Biblical record.
Hutton then sought evidence to support his idea that there must have been repeated cycles, each involving deposition on the seabed
Seabed
The seabed is the bottom of the ocean.- Ocean structure :Most of the oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources...
, uplift with tilting and erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
, and then moving undersea again for further layers to be deposited. At Glen Tilt
Glen Tilt
Glen Tilt is a glen in the extreme north of Perthshire, Scotland. Beginning at the confines of Aberdeenshire, it follows a South-westerly direction excepting for the last 4 miles, when it runs due south to Blair Atholl...
in the Cairngorm mountains
Cairngorms
The Cairngorms are a mountain range in the eastern Highlands of Scotland closely associated with the mountain of the same name - Cairn Gorm.-Name:...
he found granite penetrating metamorphic
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
schist
Schist
The schists constitute a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is...
s, in a way which indicated to him that the presumed primordial rock had been molten
Mölten
Mölten is a comune in South Tyrol in the Italian region Trentino-Alto Adige/Südtirol, located about 60 km north of Trento and about 12 km northwest of Bolzano .-Geography:...
after the strata had formed. He had read about angular unconformities
Unconformity
An unconformity is a buried erosion surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe...
as interpreted by Neptunists, and found an unconformity
Hutton's Unconformity
Hutton's Unconformity is any of various famous geological sites in Scotland. These are places identified by 18th-century Scottish geologist James Hutton as an unconformity, which provided evidence for his Plutonist theories of uniformitarianism and about the age of the Earth.-Theory of rock...
at Jedburgh
Jedburgh
Jedburgh is a town and former royal burgh in the Scottish Borders and historically in Roxburghshire.-Location:Jedburgh lies on the Jed Water, a tributary of the River Teviot, it is only ten miles from the border with England and is dominated by the substantial ruins of Jedburgh Abbey...
where layers of greywacke
Greywacke
Greywacke or Graywacke is a variety of sandstone generally characterized by its hardness, dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or lithic fragments set in a compact, clay-fine matrix. It is a texturally immature sedimentary rock generally found...
in the lower layers of the cliff face have been tilted almost vertically before being eroded to form a level plane, under horizontal layers of Old Red Sandstone
Old Red Sandstone
The Old Red Sandstone is a British rock formation of considerable importance to early paleontology. For convenience the short version of the term, 'ORS' is often used in literature on the subject.-Sedimentology:...
. In the Spring of 1788 he took a boat trip along the Berwickshire
Berwickshire
Berwickshire or the County of Berwick is a registration county, a committee area of the Scottish Borders Council, and a lieutenancy area of Scotland, on the border with England. The town after which it is named—Berwick-upon-Tweed—was lost by Scotland to England in 1482...
coast with John Playfair
John Playfair
John Playfair FRSE, FRS was a Scottish scientist and mathematician, and a professor of natural philosophy at the University of Edinburgh. He is perhaps best known for his book Illustrations of the Huttonian Theory of the Earth , which summarized the work of James Hutton...
and the geologist Sir James Hall, and found a dramatic unconformity showing the same sequence at Siccar Point
Siccar Point
Siccar Point is a rocky promontory in the county of Berwickshire on the east coast of Scotland.It is famous in the history of geology for Hutton's Unconformity found in 1788, which James Hutton regarded as conclusive proof of his uniformitarian theory of geological development.-History:Siccar...
. Playfair later recalled that "the mind seemed to grow giddy by looking so far into the abyss of time", and Hutton concluded a 1788 paper he presented at the Royal Society of Edinburgh
Royal Society of Edinburgh
The Royal Society of Edinburgh is Scotland's national academy of science and letters. It is a registered charity, operating on a wholly independent and non-party-political basis and providing public benefit throughout Scotland...
, later rewritten as a book, with the phrase "we find no vestige of a beginning, no prospect of an end."
Both Playfair and Hall wrote their own books on the theory, and for decades there was a robust debate between Hutton's supporters and the Neptunists. Georges Cuvier
Georges Cuvier
Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
's paleontological work
History of paleontology
The history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms...
in the 1790s, which established the reality of extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
, explained this by local catastrophes, after which other fixed species repopulated the affected areas. In Britain, geologists adapted this idea into "diluvial theory
Diluvium
Diluvium is a term in geology for superficial deposits formed by flood-like operations of water, and so contrasted with alluvium or alluvial deposits formed by slow and steady aqueous agencies...
" which proposed repeated worldwide annihilation and creation of new fixed species adapted to a changed environment, initially identifying the most recent catastrophe as the biblical flood.
19th century
From 1830 to 1833 Charles LyellCharles Lyell
Sir Charles Lyell, 1st Baronet, Kt FRS was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by slow-moving forces still in operation...
's multi-volume Principles of Geology
Principles of Geology
Principles of Geology, being an attempt to explain the former changes of the Earth's surface, by reference to causes now in operation, is a book by the Scottish geologist Charles Lyell....
was published. The work's subtitle was "An attempt to explain the former changes of the Earth's surface by reference to causes now in operation". He drew his explanations from field studies conducted directly before he went to work on the founding geology text, and developed Hutton's idea that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. The terms uniformitarianism for this idea, and catastrophism
Catastrophism
Catastrophism is the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope. The dominant paradigm of modern geology is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
for the opposing viewpoint, were coined by William Whewell
William Whewell
William Whewell was an English polymath, scientist, Anglican priest, philosopher, theologian, and historian of science. He was Master of Trinity College, Cambridge.-Life and career:Whewell was born in Lancaster...
in a review of Lyell's book. Principles of Geology was the most influential geological work in the middle of the 19th century.
Lyell's uniformitarianism
According to Reijer HooykaasReijer Hooykaas
Reijer Hooykaas was a historian of science. He along with Eduard Jan Dijksterhuis were pioneers in professionalizing the history of science in the Netherlands. H...
(1963), Lyell's uniformitarianism is a family of four related propositions, not a single idea:
- Uniformity of law – the laws of nature are constant across time and space.
- Uniformity of methodology – the appropriate hypotheses 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.
None of these connotations requires another, and they are not all equally inferred by uniformitarians.
Gould
Stephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....
expounded on similar propositions in Time's Arrow, Time's Cycle
Time's Arrow, Time's Cycle
Time's Arrow, Time's Cycle is a history of geology by Stephen Jay Gould offering a historical account of the conceptualization of Deep Time and uniformitarianism using the works of Thomas Burnet, James Hutton, and Charles Lyell.-Deep Time:...
(1987), stating that Lyell conflated two different types of propositions: a pair of methodological assumptions with a pair of substantive hypotheses. The four together make up Lyell's uniformitarianism.
Methodological assumptions
The two methodological assumptions are universally acclaimed by scientists, and embraced by all geologists. Gould further states that these philosophical propositions must be assumed before you can proceed as a scientist doing science. "You cannot go to a rocky outcrop and observe either the constancy of nature's laws or the working of unknown processes. It works the other way around." You first assume these propositions and "then you go to the out crop of rock."
- Uniformity of law across time and space: Natural laws are constant across space and time.
- The axiom of uniformity of law is necessary in order for scientists to extrapolate inductive inference into the unobservable past. As James Hutton wrote: “If the stone, for example, which fell today, were to rise again tomorrow, there would be an end of natural philosophy [i.e., science], our principles would fail, and we would no longer investigate the rules of nature from our observations.” In essence, the constancy of natural laws must be assumed in our study of the past, because if we do not, then we cannot meaningfully study the past. Making inferences about the past is wrapped up in the difference between studying the observable present and the unobservable past. In the observable present, induction can be regarded as self-corrective. That is to say, erroneous beliefs about the observable world can be proven wrong and corrected by other observations. This is Popper's principle of falsifiabilityFalsifiabilityFalsifiability or refutability of an assertion, hypothesis or theory is the logical possibility that it can be contradicted by an observation or the outcome of a physical experiment...
. However, past processes are not observable by their very nature. Therefore, in order to come to conclusions about the past, we must assume the invariance of nature's laws.
- "The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference which, as Bacon showed nearly four hundred years ago, is the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown and, therefore, no way of reaching general conclusions from a finite number of observations. (Since the assumption is itself vindicated by induction, it can in no way “prove” the validity of induction - an endeavor virtually abandoned after Hume demonstrated its futility two centuries ago)."
- "Uniformity is an unprovable postulate justified, or indeed required, on two grounds. First, nothing in our incomplete but extensive knowledge of history disagrees with it. Second, only with this postulate is a rational interpretation of history possible, and we are justified in seeking—as scientists we must seek—such a rational interpretation."
- Uniformity of process across time and space: If a past phenomenon can be understood as the result of a process now acting in time and space, do not invent an extinct or unknown cause as its explanation.
- Though similar to the uniformity of law, this deals with geological causes, not physico-chemical laws. “We should try to explain the past by causes now in operation without inventing extra, fancy, or unknown causes, however plausible in logic, if available processes suffice.” This is known as the scientific principle of parsimony or Occam's razorOccam's razorOccam's razor, also known as Ockham's razor, and sometimes expressed in Latin as lex parsimoniae , is a principle that generally recommends from among competing hypotheses selecting the one that makes the fewest new assumptions.-Overview:The principle is often summarized as "simpler explanations...
.
- "Strict uniformitarianism may often be a guarantee against pseudo-scientific phantasies and loose conjectures, but it makes one easily forget that the principle of uniformity is not a law, not a rule established after comparison of facts, but a methodological principle, preceding the observation of facts . . . It is the logical principle of parsimony of causes and of economy of scientific notions. By explaining past changes by analogy with present phenomena, a limit is set to conjecture, for there is only one way in which two things are equal, but there are an infinity of ways in which they could be supposed different."
- Gould simplified the issue, noting that Lyell's “uniformity of process” was also an assumption: “As such, it is another a priori methodological assumption shared by all scientists and not a statement about the empirical world.”
Substantive hypotheses
The substantive hypotheses were controversial and, in some cases, accepted by few. These hypotheses are judged true or false on empirical grounds through scientific observation and repeated experimental data. This is in contrast with the previous two philosophical assumptions that come before one can do science and so cannot be tested or falsified by science.
- Uniformity of rate across time and space: Change is typically slow, steady, and gradual.
- Uniformity of rate (or GradualismGradualismGradualism is the belief in or the policy of advancing toward a goal by gradual, often slow stages.-Politics and society:In politics, the concept of gradualism is used to describe the belief that change ought to be brought about in small, discrete increments rather than in abrupt strokes such as...
) is what most people (including geologists) think of when they hear the word “uniformitarianism," confusing this hypothesis with the entire definition. As late as 1990, Lemon, in his textbook of stratigraphy, affirmed that “The uniformitarian view of earth history held that all geologic processes proceed continuously and at a very slow pace.”
- Gould explained Hutton's view of uniformity of rate; mountain ranges or grand canyons are built by accumulation of nearly insensible changes added up through vast time. Some major events such as floods, earthquakes, and eruptions, do occur. But these catastrophes are strictly local. They neither occurred in the past, nor shall happen in the future, at any greater frequency or extent than they display at present. In particular, the whole earth is never convulsed at once.
- Uniformity of state across time and space: Change is evenly distributed throughout space and time.
- The uniformity of state hypothesis (i.e., steady-stateism) implies that throughout the history of our earth there is no progress in any inexorable direction. The planet has almost always looked and behaved as it does now. Change is continuous, but leads nowhere. The earth is in balance: a dynamic steady state.
20th century
Stephen Jay GouldStephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....
's first scientific paper, Is uniformitarianism necessary? (1965), reduced these four interpretations to two, methodological and substantive uniformitarianism. He dismissed the first principle, which asserted spatial and temporal invariance of natural laws, as no longer an issue of debate. He rejected the second as an unjustified limitation on scientific inquiry, as it constrains past geologic rates and conditions to those of the present. So, uniformitarianism was unnecessary.
Uniformitarianism was originally proposed in contrast to catastrophism
Catastrophism
Catastrophism is the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope. The dominant paradigm of modern geology is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
, which states that the distant past "consisted of epochs of paroxysmal and catastrophic action interposed between periods of comparative tranquility" 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
Channeled scablands
The Channeled Scablands are a unique geological erosion feature in the U.S. state of Washington. They were created by the cataclysmic Missoula Floods that swept periodically across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. Geologist J Harlen Bretz coined...
due to the catastrophic Missoula
Missoula Floods
The Missoula Floods refer to the cataclysmic floods that swept periodically across eastern Washington and down the Columbia River Gorge at the end of the last ice age. The glacial flood events have been researched since the 1920s...
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 are infrequent on human time-scales can have important consequences in geologic history.
Derek Ager has 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
Charles Lyell
Sir Charles Lyell, 1st Baronet, Kt FRS was a British lawyer and the foremost geologist of his day. He is best known as the author of Principles of Geology, which popularised James Hutton's concepts of uniformitarianism – the idea that the earth was shaped by slow-moving forces still in operation...
thought that ordinary geological processes would cause Niagara Falls
Niagara Falls
The Niagara Falls, located on the Niagara River draining Lake Erie into Lake Ontario, is the collective name for the Horseshoe Falls and the adjacent American Falls along with the comparatively small Bridal Veil Falls, which combined form the highest flow rate of any waterfalls in the world and has...
to move upstream to Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
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. The present may not be a long enough key to penetrate the deep lock of the past. Geologic processes may have been active at different rates in the past that humans have not observed. “By force of popularity, uniformity of rate has persisted to our present day. For more than a century, Lyell’s 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 consensus is that Earth's history
History of Earth
The history of the Earth describes the most important events and fundamental stages in the development of the planet Earth from its formation 4.578 billion years ago to the present day. Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's...
is a slow, gradual process punctuated by occasional natural catastrophic events that have affected Earth and its inhabitants. In practice it is reduced from Lyell's conflation 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
Actualism
In contemporary analytic philosophy, actualism is a position on the ontological status of possible worlds that holds that everything that exists is actual. Another phrasing of the thesis is that the domain of unrestricted quantification ranges over all and only actual existents...
is the cornerstone of paleoecology
Paleoecology
Paleoecology uses data from fossils and subfossils to reconstruct the ecosystems of the past. It involves the study of fossil organisms and their associated remains, including their life cycle, living interactions, natural environment, and manner of death and burial to reconstruct the...
.
See also
- GradualismGradualismGradualism is the belief in or the policy of advancing toward a goal by gradual, often slow stages.-Politics and society:In politics, the concept of gradualism is used to describe the belief that change ought to be brought about in small, discrete increments rather than in abrupt strokes such as...
- CatastrophismCatastrophismCatastrophism is the theory that the Earth has been affected in the past by sudden, short-lived, violent events, possibly worldwide in scope. The dominant paradigm of modern geology is uniformitarianism , in which slow incremental changes, such as erosion, create the Earth's appearance...
- Scientific consensusScientific consensusScientific consensus is the collective judgment, position, and opinion of the community of scientists in a particular field of study. Consensus implies general agreement, though not necessarily unanimity. Scientific consensus is not by itself a scientific argument, and it is not part of the...
- Paradigm shiftParadigm shiftA Paradigm shift is, according to Thomas Kuhn in his influential book The Structure of Scientific Revolutions , a change in the basic assumptions, or paradigms, within the ruling theory of science...
- History of geologyHistory of geologyThe history of geology is concerned with the development of the natural science of geology. Geology is the scientific study of the origin, history, and structure of the Earth. Throughout the ages geology provides essential theories and data that shape how society conceptualizes the...
- History of paleontologyHistory of paleontologyThe history of paleontology traces the history of the effort to understand the history of life on Earth by studying the fossil record left behind by living organisms...