In , in the third edition of his Recherches. These discoveries all exerted a profound effect on both the scientific and popular imagination and presented a vivid picture of the abundance, diversity, and enormous size and strangeness of past forms of life. One of the points which had been at issue between the Huttonians and Wernerians had been the question of the origin of basalt.
The volcanic origin of basalt was generally accepted in Britain after when the Reverend William Buckland and the Reverend William Daniel Conybeare visited the Giant's Causeway in Ireland, where they found clear evidence that that particularly famous basalt formation had resulted from a volcanic outflow. In general, British geologists tended to abandon Werner's idea that rock strata had been formed by crystallization or deposition from a universal ocean, and had accepted the Huttonian idea that the strata had been laid down beneath the sea and had subse- quently been elevated.
However, in accepting the concept of movements of the land they necessarily accepted the occurrence of catastrophes during the history of the earth, because they could not conceive how elevations sufficient to create the existing hills and mountains could occur without catastrophes.
In the English geologist Thomas Webster published a description of the geology of the Isle of Wight in which he showed that the chalk strata forming the central range of hills in the island were vertical or very steeply inclined and that they formed one side of an anticlinal fold, the opposite side of which, he discovered on the south shore of the Isle of Wight.
Webster showed that the strata must once have been continuous in a great arch extending across the whole Isle of Wight and that most of this arch had since been removed. The chalk strata which had formed this arch had been formed as horizontal beds of sediment in the sea, so that their upraising to form the arch had required their uplift, bending, and disturbance on a great scale. This kind of disturbance was explicable to Webster only by some enormous convulsion of a kind entirely different from anything experienced in modern times.
The basic as- sumptions of geologists in the 's, whether Hut- tonian or Wernerian, was stated by William Whewell in In the dislocation of provinces, in the elevation of hills from the bottom of the sea, in the comminution and dispersion of vast tracts of the hardest rock, in the obliteration and renewal of a whole creation they seemed to themselves to see They spoke of a break in the continuity of nature's operations; of the present state of things as permanent and tranquil, the past having been progressive and violent.
During the 's the evidence for convulsive and catastrophic changes in the history of the earth seemed so compelling and universal that the revival of James Hutton's concept of a continuous process shaping the earth's surface indefinitely through time is a develop- ment requiring some explanation. Two factors seemed to have played a role. The first may have been an increasing interest in the study of volcanic activity in different parts of the world.
Beginning in Leopold von Buch made extensive studies in the Alps where he deter- mined that their structure showed that they had been uplifted. From his further observations on the Alban Hills and Vesuvius in Italy and on Etna in Sicily he became convinced of the vast extent and power of volcanic activity, and of its capacity to uplift whole areas of country. In he visited the Auvergne district of France where he found a series of volcanoes of different ages, all of which were connected with an underlying platform of granite.
The other Puys, which possessed the conical forms and craters characteristic of volcanoes, had been formed by the ordinary process of volcanic eruption. After a visit to Norway, where he observed granite veins extending into an overlying fossil-bearing limestone which was highly altered along the lines of contact, von Buch travelled to Madeira and the Canary Islands. There he saw the results of volcanic activity on a still larger scale and studied the way in which the islands had been formed as a result of volcanic action.
He concluded that most oceanic islands were the products of volcanic activity. When von Buch studied the form of volcanoes he noted that they were both conical in form and strati- fied, with the strata sloping away on all sides from the crater's summit. He decided that this structure was not the result of accumulated lava flows, because the lava emerged in small streams which did not form continu- ous sheets over the whole surface of the mountain. When he compared his observations in the Canary Islands with those he had made in central France, von Buch decided that each volcano had resulted originally from a dome-shaped extrusion of molten rock from the interior of the earth.
More often, however, the extrusion might burst like a bubble at the summit and collapse inward, thereby forming a cone-shaped vol- cano of typical form with a crater marking the site of explosion.
In this theory each volcanic mountain was the product of a single violent eruption instead of the accumulated product of a long series of eruptions extended over a great period of time. On his return to Europe, von Buch again studied the Alps for a number of years and decided that they had been formed by a process of upheaval from below, the upheaving force being volcanic rocks which could not find their way to the surface because of the thick- ness of the overlying rock strata.
In William Daniel Conybeare suggested that volcanic activity sustained over a long period might be able to produce a large scale elevation of the land. Volcanoes were studied by Charles Daubeny, and by George Poulett Scrope and both studied the area of extinct volcanoes in the Auvergne district of France as well as those in Italy and Sicily. The other factor which may have played a role in extending the time scale of earth history was the de- velopment of paleontology, which had also seemed to support catastrophism by requiring the extinction of so many successive assemblages of animals and plants.
However, the succession of floras and faunas revealed by paleontology also required greatly lengthened pe- riods of time. In addition, the detailed study of the fossil animals and plants found together in a single bed frequently suggested the existence of conditions analogous to those of the present. For instance, in the Tilgate Forest bed, studied by Gideon Mantell in and subsequent years, there was a collection of the bones of turtles, one or more species of crocodiles, freshwater shells, and the remains of various plants including tree ferns and large weeds.
There were successive layers of clay and sand, such as might have been laid down in a modern river delta, and the animals and plants were comparable to those which might live in a river delta in a modern tropical country.
These fossils, therefore, suggested that conditions on the earth's surface at a very remote period of time had been comparable with those of modern times, although the climate and latitude of Great Britain had then been much warmer. In Charles Lyell gave a reverse kind of analogy when he compared the plants and animals living in modern freshwater lakes in Scotland with the fossil animals and plants found in freshwater marls of the Paris basin, and found the assemblage of species very similar in both instances.
From to Charles Lyell was first a law student and later a practicing barrister, but through the whole time, he was an enthusiastic amateur geologist and naturalist.
He travelled frequently and extensively. In he had toured Switzerland and northern Italy. In he returned to Switzerland and this time went as far south in Italy as Rome. He made frequent excursions on horseback through southern England, and in spent many weeks in Paris where he became acquainted with the Parisian geologists and studied the geology of the Paris basin.
In he spent an extended period in Scotland. These travels gave him a broader experience of landscape, geography, and. In a letter to Roderick Murchison written as he was returning northward, Lyell expressed the geological conviction to which his tour had led him:. That no causes whatever have from the earliest time to which we can look back, to the present, ever acted but those now acting and that they never acted with different degrees of energy from that which they now exert.
Lyell, 2 vols. He was stating the central principle of what was to be known as uniformitarianism. As a principle, it was the outgrowth of Lyell's geological experience, but it must be emphasized that it was not, and is not, a demonstrable scientific conclusion. Instead, it is a statement of faith and a working hypothesis which is, nonetheless, a hypothesis indispensable to the progress of geology as a science.
Lyell assumed that gradual causes acting through long periods of time might exert large-scale effects. His further assumption, that all geological effects are the result of gradual causes acting over large periods, required him to study relentlessly the existing processes going on both in the earth and over its surface, to pursue their consequences, and to estimate their rates.
His principle of uniformity re- quired Lyell always to attempt to explain geological phenomena and never to abandon this attempt to seek explanation by dismissing phenomena as the result of catastrophic events of unknown origin and magnitude. Lyell assumed that the order of nature and the physical laws of nature remained constant through time. He saw, too, that our only possibility of attaining knowl- edge of the geological past was by analogy with mod- ern conditions. The geologist had to assume that con- ditions in the past were comparable to those of the present and that processes going on in the past were comparable to processes going on at the present time, or else he would have to abandon all hope of acquiring any knowledge of the past.
Furthermore, Lyell's principle of uniformity opened up to the geologist a multitude of questions for investi- gation because the whole present order of nature, existing both over the earth's surface and within its interior, became relevant to his purpose.
Hence, the geologist must seek to learn what is going on at the present in order to understand what has gone on in the past. Catastrophism, on the other hand, removes the necessity for investigating modern processes be- cause events in the past are considered to have no counterparts in the present. The effect of catastrophic explanations in each instance in which they were used and in which they are used today, is to close off further investigation.
Lyell stressed that an enlarged view of the existing order of nature was the primary requisite for a geologist, and the chief means of attaining this enlarged view was travel.
He wrote:. To travel is of first, second, and third importance to those who desire to originate just and comprehensive views con- cerning the structure of our globe. Lyell, Principles of Geology, 11th ed. During his lifetime Lyell upheld the principle of uniformity in eleven successive editions of his Principles of Geology, published between and , and in other books and memoirs.
With unequalled insight, he interpreted a vast range of geological data in terms of processes observable in the modern world. Of even more far-reaching significance was his influence on Charles Darwin. During the voyage of the H. Beagle, , Darwin came to appreciate the great value of the approach to geology embodied in Lyell's Principles. He then applied the same principles to the interpretation of the geological history of species and considered what would be the effect of a modern process, namely, natural selection, if it had continued to act through an indefinite period of past time.
Darwin's theory of the origin of species by natural. Towards the end of Lyell's life uniformitarianism was attacked by the physicist, Lord Kelvin, who in argued that if the earth had been formed originally as a hot molten body which had later cooled but which also continued to lose heat by radiation, its age could be calculated by extrapolating backward from its pres- ent rate of heat loss.
Kelvin assumed that there was no source of heat within the earth, other than that which was present there when the earth was formed. On his assumptions he showed that the age of the earth could not be greater than ,, years and was probably much less. This short and restricted time span for the age of the earth would not allow sufficient time for the extremely slow gradual geological processes, as viewed by Lyell, to bring about the actual geological changes which had occurred.
The history of the earth if thus compressed in time would necessarily become violent and catastrophic. This concept of the earth's severely limited age would not allow time, either, for the slow process of evolution of living species by natu- ral selection, as viewed by Charles Darwin.
In the face of Kelvin's calculations, geologists tended to retreat from their advocacy of uniformitarianism after Lyell's death in However, with the discovery of radioactivity, it was pointed out by Ernest Rutherford in that the radioactive elements did provide a steady source of heat within the earth. The assumptions on which Kelvin had based his estimates of the age of the earth were, therefore, invalid and his calculations meaningless.
Geologists did not, how- ever, recover immediately their confidence in uni- formitarianism, and in many instances they continued to believe that volcanic activity and mountain building had gone on during particular periods of the geological past on a scale, and with an intensity, unparalleled in the present.
In recent years, however, radioactive methods of dating rocks have shown that instances of supposed catastrophic volcanic activity and mountain building have, in fact, occurred over long periods of geological time. The theory of uniformitarianism taught that the present was the key to the past and exactly the same slow process that we see today is the one responsible for the formation of all the geological rock …show more content… This meant that the current biblical beliefs at that time of a young earth, the recent history of life on earth and the worldwide flood of Noah were discredited.
So uniformitarianism dethroned catastrophism and evolution dethroned biblical creationism and both became the dominant theories in academia and science until the present time. Currently, academia and science are clinging to uniformitarianism and biological macroevolution with all the strength they can muster. However, large splits have been seen in the ranks. During the last 50 years an enormous amount of information has been collected that supports catastrophism and intelligent design.
The Mount St. Helens eruption and subsequent erosion has taught us that rapid deposition and rapid canyon erosion is a fact. Get Access. Satisfactory Essays. Have you seen a news clip or a video showing a volcano erupting, or an earthquake shaking a city?
One of the interesting things about those events is that they occur today in the same way that they have in the past. Scientists look at modern-day geologic events—whether as sudden as an earthquake or as slow as the erosion of a river valley—to get a window into past events. This is known as uniformitarianism : the idea that Earth has always changed in uniform ways and that the present is the key to the past.
However, prior to , uniformitarianism was not the prevailing theory. Until that time, scientists subscribed to the idea of catastrophism. Catastrophism suggested the features seen on the surface of Earth, such as mountains, were formed by large, abrupt changes—or catastrophes. When discussing past climates, opponents to uniformitarianism may speak of no-analog changes. This idea suggests that certain communities or conditions that existed in the past may not be found on Earth today.
The idea of catastrophism was eventually challenged based on the observations and studies of two men—James Hutton and Charles Lyell. Hutton — was a Scottish farmer and naturalist. In his observations of the world around him, he became convinced natural processes, such as mountain building and erosion, occurred slowly over time through geologic forces that have been at work since Earth first formed. He eventually turned his observations and ideas into what became known as the Principle of Uniformitarianism.
Among the scientists who agreed with Hutton was Charles Lyell. Lyell — was a Scottish geologist. He found his own examples of these processes in his examination of rocks and sediments. For example, he discovered evidence that sea levels had risen and fallen in the past, that volcanoes may exist atop older rocks, and that valleys form slowly by the erosional power of water. The combined efforts of Lyell and Hutton became the foundation of modern geology. Charles Darwin, the founder of evolutionary biology , looked at uniformitarianism as support for his theory of how new species emerge.
The evolution of life, he realized, required vast amounts of time, and the science of geology now showed Earth was extremely old. If there had been plenty of time for mountains to rise up and erode away, then there had also been enough time for millions of species to emerge, and either evolve into new species or go extinct.
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