Moosach is a municipality in the Upper Bavarian district of Ebersberg and a member of the Verwaltungsgemeinschaft (administrative community) of Glonn.
111-558: The community lies in a picturesque setting in an ice-age moraine landscape about 500 m in elevation and lends itself well to hiking . In the heights of the moraine that ring the town are lakes, among them the Steinsee, a bathing lake also favoured by visitors from Munich . Somewhat farther away lies the Kitzlsee, a protected landscape. Moosach comprises a number of surrounding hamlets and lone homesteads such as Falkenberg (with
222-454: A proglacial lake above the valley created by an ice dam as a result of the 1815 eruption of Mount Tambora , which threatened to cause a catastrophic flood when the dam broke. Perraudin attempted unsuccessfully to convert his companions to his theory, but when the dam finally broke, there were only minor erratics and no striations, and Venetz concluded that Perraudin was right and that only ice could have caused such major results. In 1821 he read
333-526: A fertilizer that causes massive algal blooms that pulls large amounts of CO 2 out of the atmosphere. This in turn makes it even colder and causes the glaciers to grow more. In 1956, Ewing and Donn hypothesized that an ice-free Arctic Ocean leads to increased snowfall at high latitudes. When low-temperature ice covers the Arctic Ocean there is little evaporation or sublimation and the polar regions are quite dry in terms of precipitation, comparable to
444-490: A geological tour of the north of Scotland with George Maxwell-Clerk, ancestor of the famous James Clerk Maxwell . In 1768, Hutton returned to Edinburgh, letting his farms to tenants but continuing to take an interest in farm improvements and research which included experiments carried out at Slighhouses . He developed a red dye made from the roots of the madder plant. He had a house built in 1770 at St John's Hill, Edinburgh, overlooking Salisbury Crags . This later became
555-570: A geologist and professor of forestry at an academy in Dreissigacker (since incorporated in the southern Thuringian city of Meiningen ), adopted Esmark's theory. In a paper published in 1832, Bernhardi speculated about the polar ice caps once reaching as far as the temperate zones of the globe. In Val de Bagnes , a valley in the Swiss Alps , there was a long-held local belief that the valley had once been covered deep in ice, and in 1815
666-408: A local chamois hunter called Jean-Pierre Perraudin attempted to convert the geologist Jean de Charpentier to the idea, pointing to deep striations in the rocks and giant erratic boulders as evidence. Charpentier held the general view that these signs were caused by vast floods, and he rejected Perraudin's theory as absurd. In 1818 the engineer Ignatz Venetz joined Perraudin and Charpentier to examine
777-467: A molten globe. In order to persuade the skeptics, Agassiz embarked on geological fieldwork. He published his book Study on Glaciers ("Études sur les glaciers") in 1840. Charpentier was put out by this, as he had also been preparing a book about the glaciation of the Alps. Charpentier felt that Agassiz should have given him precedence as it was he who had introduced Agassiz to in-depth glacial research. As
888-463: A portion of the moisture must be condensed and appear in visible form. He investigated the available data regarding rainfall and climate in different regions of the globe, and came to the conclusion that the rainfall is regulated by the humidity of the air on the one hand, and mixing of different air currents in the higher atmosphere on the other. Hutton taught that biological and geological processes are interlinked. James Lovelock , who developed
999-444: A possible mechanism affecting them: Hutton gave the example that where dogs survived through "swiftness of foot and quickness of sight... the most defective in respect of those necessary qualities, would be the most subject to perish, and that those who employed them in greatest perfection... would be those who would remain, to preserve themselves, and to continue the race". Equally, if an acute sense of smell became "more necessary to
1110-544: A prize-winning paper on the theory to the Swiss Society, but it was not published until Charpentier, who had also become converted, published it with his own more widely read paper in 1834. In the meantime, the German botanist Karl Friedrich Schimper (1803–1867) was studying mosses which were growing on erratic boulders in the alpine upland of Bavaria. He began to wonder where such masses of stone had come from. During
1221-499: A result of personal quarrels, Agassiz had also omitted any mention of Schimper in his book. It took several decades before the ice age theory was fully accepted by scientists. This happened on an international scale in the second half of the 1870s, following the work of James Croll , including the publication of Climate and Time, in Their Geological Relations in 1875, which provided a credible explanation for
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#17327765010481332-411: A significant causal factor of the 40 million year Cenozoic Cooling trend. They further claim that approximately half of their uplift (and CO 2 "scrubbing" capacity) occurred in the past 10 million years. There is evidence that greenhouse gas levels fell at the start of ice ages and rose during the retreat of the ice sheets, but it is difficult to establish cause and effect (see the notes above on
1443-782: A similar penetration of volcanic rock through sedimentary rock in Edinburgh , at Salisbury Crags , adjoining Arthur's Seat – this area of the Crags is now known as Hutton's Section. He found other examples in Galloway in 1786, and on the Isle of Arran in 1787. The existence of angular unconformities had been noted by Nicolas Steno and by French geologists including Horace-Bénédict de Saussure , who interpreted them in terms of Neptunism as "primary formations". Hutton wanted to examine such formations himself to see "particular marks" of
1554-456: A son by a Miss Edington, and though he gave his child, James Smeaton Hutton, financial assistance, he had little to do with the boy, who went on to become a post-office clerk in London. Hutton developed several hypotheses to explain the rock formations he saw around him, but according to Playfair he "was in no haste to publish his theory; for he was one of those who are much more delighted with
1665-542: A stable and a beergarden), Baumhau, Altenburg and Berghofen. In 1990, Moosach celebrated 1,200 years of existence, witnessed in a donation document of the Roman Catholic Archdiocese of Munich and Freising . The community's name goes back to the Moosach brook: " Ache flowing through the moss", Ache being a regional word meaning "swiftly flowing water". The Moosach rises from 7 springs at the foot of
1776-578: Is estimated to potentially outweigh the orbital forcing of the Milankovitch cycles for hundreds of thousands of years. Each glacial period is subject to positive feedback which makes it more severe, and negative feedback which mitigates and (in all cases so far) eventually ends it. An important form of feedback is provided by Earth's albedo , which is how much of the sun's energy is reflected rather than absorbed by Earth. Ice and snow increase Earth's albedo, while forests reduce its albedo. When
1887-493: Is now known as the Hutton or "Great" Unconformity at Inchbonny, Jedburgh , in layers of sedimentary rock . As shown in the illustrations to the right, layers of greywacke in the lower layers of the cliff face are tilted almost vertically, and above an intervening layer of conglomerate lie horizontal layers of Old Red Sandstone . He later wrote of how he "rejoiced at my good fortune in stumbling upon an object so interesting in
1998-649: Is that several factors are important: atmospheric composition , such as the concentrations of carbon dioxide and methane (the specific levels of the previously mentioned gases are now able to be seen with the new ice core samples from the European Project for Ice Coring in Antarctica (EPICA) Dome C in Antarctica over the past 800,000 years); changes in Earth's orbit around the Sun known as Milankovitch cycles ;
2109-516: Is the increased aridity occurring with glacial maxima, which reduces the precipitation available to maintain glaciation. The glacial retreat induced by this or any other process can be amplified by similar inverse positive feedbacks as for glacial advances. According to research published in Nature Geoscience , human emissions of carbon dioxide (CO 2 ) will defer the next glacial period. Researchers used data on Earth's orbit to find
2220-473: The Alps of Savoy . Two years later he published an account of his journey. He reported that the inhabitants of that valley attributed the dispersal of erratic boulders to the glaciers, saying that they had once extended much farther. Later similar explanations were reported from other regions of the Alps. In 1815 the carpenter and chamois hunter Jean-Pierre Perraudin (1767–1858) explained erratic boulders in
2331-655: The Carboniferous and early Permian periods. Correlatives are known from Argentina, also in the center of the ancient supercontinent Gondwanaland . Although the Mesozoic Era retained a greenhouse climate over its timespan and was previously assumed to have been entirely glaciation-free, more recent studies suggest that brief periods of glaciation occurred in both hemispheres during the Early Cretaceous . Geologic and palaeoclimatological records suggest
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#17327765010482442-520: The Elements of Agriculture . He distinguished between heritable variation as the result of breeding, and non-heritable variations caused by environmental differences such as soil and climate. Though he saw his "principle of variation" as explaining the development of varieties, Hutton rejected the idea that evolution might originate species as a "romantic fantasy", according to palaeoclimatologist Paul Pearson. Influenced by deism , Hutton thought
2553-491: The Gaia hypothesis in the 1970s, cites Hutton as saying that the Earth was a superorganism and that its proper study should be physiology. Lovelock writes that Hutton's view of the Earth was rejected because of the intense reductionism among 19th-century scientists. Hutton also advocated uniformitarianism for living creatures – evolution , in a sense – and even suggested natural selection as
2664-683: The Himalayas are a major factor in the current ice age, because these mountains have increased Earth's total rainfall and therefore the rate at which carbon dioxide is washed out of the atmosphere, decreasing the greenhouse effect. The Himalayas' formation started about 70 million years ago when the Indo-Australian Plate collided with the Eurasian Plate , and the Himalayas are still rising by about 5 mm per year because
2775-765: The Late Ordovician and the Silurian period. The evolution of land plants at the onset of the Devonian period caused a long term increase in planetary oxygen levels and reduction of CO 2 levels, which resulted in the late Paleozoic icehouse . Its former name, the Karoo glaciation, was named after the glacial tills found in the Karoo region of South Africa. There were extensive polar ice caps at intervals from 360 to 260 million years ago in South Africa during
2886-482: The Pleistocene Ice Age. Because this highland is at a subtropical latitude, with four to five times the insolation of high-latitude areas, what would be Earth's strongest heating surface has turned into a cooling surface. Kuhle explains the interglacial periods by the 100,000-year cycle of radiation changes due to variations in Earth's orbit. This comparatively insignificant warming, when combined with
2997-645: The Royal Society of Edinburgh . He was particularly friendly with physician and chemist Joseph Black , and together with Adam Smith they founded the Oyster Club for weekly meetings. Between 1767 and 1774 Hutton had close involvement with the construction of the Forth and Clyde canal , making full use of his geological knowledge, both as a shareholder and as a member of the committee of management, and attended meetings including extended site inspections of all
3108-715: The Turonian , otherwise the warmest period of the Phanerozoic, are disputed), ice sheets and associated sea ice appear to have briefly returned to Antarctica near the very end of the Maastrichtian just prior to the Cretaceous-Paleogene extinction event . The Quaternary Glaciation / Quaternary Ice Age started about 2.58 million years ago at the beginning of the Quaternary Period when
3219-438: The seabed , uplift with tilting and erosion then undersea again for further layers to be deposited. On the belief that this was due to the same geological forces operating in the past as the very slow geological forces seen operating at the present day, the thicknesses of exposed rock layers implied to him enormous stretches of time. Though Hutton circulated privately a printed version of the abstract of his Theory ( Concerning
3330-585: The "Father of Modern Geology," he played a key role in establishing geology as a modern science. Hutton advanced the idea that the physical world's remote history can be inferred from evidence in present-day rocks. Through his study of features in the landscape and coastlines of his native Scottish lowlands , such as Salisbury Crags or Siccar Point , he developed the theory that geological features could not be static but underwent continuing transformation over indefinitely long periods of time. From this he argued, in agreement with many other early geologists, that
3441-618: The Atlantic, increasing heat transport into the Arctic, which melted the polar ice accumulation and reduced other continental ice sheets. The release of water raised sea levels again, restoring the ingress of colder water from the Pacific with an accompanying shift to northern hemisphere ice accumulation. According to a study published in Nature in 2021, all glacial periods of ice ages over
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3552-630: The Balfour family home and, in 1840, the birthplace of the psychiatrist James Crichton-Browne . Hutton was one of the most influential participants in the Scottish Enlightenment , and fell in with numerous first-class minds in the sciences including mathematician John Playfair , philosopher David Hume and economist Adam Smith . Hutton held no position in the University of Edinburgh and communicated his scientific findings through
3663-681: The Earth could not be young. He was one of the earliest proponents of what in the 1830s became known as uniformitarianism , the science which explains features of the Earth's crust as the outcome of continuing natural processes over the long geologic time scale . Hutton also put forward a thesis for a 'system of the habitable Earth' proposed as a deistic mechanism designed to keep the world eternally suitable for humans, an early attempt to formulate what today might be called one kind of anthropic principle . Some reflections similar to those of Hutton can be found in publications of his contemporaries, such as
3774-513: The French naturalist Georges-Louis Leclerc de Buffon , but it is chiefly Hutton's pioneering work that established the field. Hutton was born in Edinburgh on 3 June O.S. 1726, as one of five children of Sarah Balfour and William Hutton, a merchant who was Edinburgh City Treasurer. Hutton's father died in 1729, when he was three. He was educated at the High School of Edinburgh where he
3885-467: The Indo-Australian plate is still moving at 67 mm/year. The history of the Himalayas broadly fits the long-term decrease in Earth's average temperature since the mid-Eocene , 40 million years ago. Another important contribution to ancient climate regimes is the variation of ocean currents, which are modified by continent position, sea levels and salinity, as well as other factors. They have
3996-579: The North Atlantic Ocean far enough to block the Gulf Stream. Ice sheets that form during glaciations erode the land beneath them. This can reduce the land area above sea level and thus diminish the amount of space on which ice sheets can form. This mitigates the albedo feedback, as does the rise in sea level that accompanies the reduced area of ice sheets, since open ocean has a lower albedo than land. Another negative feedback mechanism
4107-603: The North Atlantic during a warming cycle may also reduce the global ocean water circulation . Such a reduction (by reducing the effects of the Gulf Stream ) would have a cooling effect on northern Europe, which in turn would lead to increased low-latitude snow retention during the summer. It has also been suggested that during an extensive glacial, glaciers may move through the Gulf of Saint Lawrence , extending into
4218-471: The Royal Society of Edinburgh , vol. I, Part II, pp. 209–304, plates I and II, published 1788. He put forward the view that "from what has actually been, we have data for concluding with regard to that which is to happen thereafter." This restated the Scottish Enlightenment concept which David Hume had put in 1777 as "all inferences from experience suppose ... that the future will resemble
4329-827: The Scandinavian peninsula. He regarded glaciation as a regional phenomenon. Only a few years later, the Danish-Norwegian geologist Jens Esmark (1762–1839) argued for a sequence of worldwide ice ages. In a paper published in 1824, Esmark proposed changes in climate as the cause of those glaciations. He attempted to show that they originated from changes in Earth's orbit. Esmark discovered the similarity between moraines near Haukalivatnet lake near sea level in Rogaland and moraines at branches of Jostedalsbreen . Esmark's discovery were later attributed to or appropriated by Theodor Kjerulf and Louis Agassiz . During
4440-544: The Swiss Alps with his former university friend Louis Agassiz (1801–1873) and Jean de Charpentier. Schimper, Charpentier and possibly Venetz convinced Agassiz that there had been a time of glaciation. During the winter of 1836–37, Agassiz and Schimper developed the theory of a sequence of glaciations. They mainly drew upon the preceding works of Venetz, Charpentier and on their own fieldwork. Agassiz appears to have been already familiar with Bernhardi's paper at that time. At
4551-456: The System of the Earth, its Duration and Stability to Society meeting on 4 July 1785, which he had printed and circulated privately. In it, he outlined his theory as follows; The solid parts of the present land appear in general, to have been composed of the productions of the sea, and of other materials similar to those now found upon the shores. Hence we find reason to conclude: 1st, That
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4662-661: The System of the Earth, its Duration, and Stability ) which he read at a meeting of the Royal Society of Edinburgh on 4 July 1785; the full account of his theory as read at 7 March 1785 and 4 April 1785 meetings did not appear in print until 1788. It was titled Theory of the Earth ; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe and appeared in Transactions of
4773-579: The University of Edinburgh. After a two-year stay in Paris, James Hutton arrived in Leiden in 1749, where he enrolled at the University of Leiden on 14 August 1749, at the home of the then rector magnificus Joachim Schwartz to obtain a doctorate in medicine. He stayed with the widow Van der Tas (née Judith Bouvat) at the Langebrug, which corresponds to the current address Langebrug 101 in Leiden. His supervisor
4884-880: The Val de Bagnes in the Swiss canton of Valais as being due to glaciers previously extending further. An unknown woodcutter from Meiringen in the Bernese Oberland advocated a similar idea in a discussion with the Swiss-German geologist Jean de Charpentier (1786–1855) in 1834. Comparable explanations are also known from the Val de Ferret in the Valais and the Seeland in western Switzerland and in Goethe 's scientific work . Such explanations could also be found in other parts of
4995-621: The ability to cool (e.g. aiding the creation of Antarctic ice) and the ability to warm (e.g. giving the British Isles a temperate as opposed to a boreal climate). The closing of the Isthmus of Panama about 3 million years ago may have ushered in the present period of strong glaciation over North America by ending the exchange of water between the tropical Atlantic and Pacific Oceans. Analyses suggest that ocean current fluctuations can adequately account for recent glacial oscillations. During
5106-402: The air temperature decreases, ice and snow fields grow, and they reduce forest cover. This continues until competition with a negative feedback mechanism forces the system to an equilibrium. One theory is that when glaciers form, two things happen: the ice grinds rocks into dust, and the land becomes dry and arid. This allows winds to transport iron rich dust into the open ocean, where it acts as
5217-424: The amount found in mid-latitude deserts . This low precipitation allows high-latitude snowfalls to melt during the summer. An ice-free Arctic Ocean absorbs solar radiation during the long summer days, and evaporates more water into the Arctic atmosphere. With higher precipitation, portions of this snow may not melt during the summer and so glacial ice can form at lower altitudes and more southerly latitudes, reducing
5328-500: The arguments from Richard Kirwan who thought Hutton's ideas were atheistic and not logical, Hutton published a two volume version of his theory in 1795, consisting of the 1788 version of his theory (with slight additions) along with a lot of material drawn from shorter papers Hutton already had to hand on various subjects such as the origin of granite. It included a review of alternative theories, such as those of Thomas Burnet and Georges-Louis Leclerc, Comte de Buffon . The whole
5439-474: The beginning of 1837, Schimper coined the term "ice age" ( "Eiszeit" ) for the period of the glaciers. In July 1837 Agassiz presented their synthesis before the annual meeting of the Swiss Society for Natural Research at Neuchâtel. The audience was very critical, and some were opposed to the new theory because it contradicted the established opinions on climatic history. Most contemporary scientists thought that Earth had been gradually cooling down since its birth as
5550-568: The bladder and gave up field work to concentrate on finishing his books. A dangerous and painful operation failed to resolve his illness. He died in Edinburgh and was buried in the vault of Andrew Balfour, opposite the vault of his friend Joseph Black , in the now sealed south-west section of Greyfriars Kirkyard in Edinburgh, commonly known as the Covenanter's Prison. Hutton did not marry and had no legitimate children. Around 1747, he had
5661-552: The bottom of the sea, the place where they were collected, to the stations in which they now remain above the level of the ocean. In the summer of 1785 at Glen Tilt and other sites in the Cairngorm mountains in the Scottish Highlands , Hutton found granite penetrating metamorphic schists , in a way which indicated that the granite had been molten at the time. This was Hutton's first geological field trip and he
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#17327765010485772-495: The causes of ice ages. There are three main types of evidence for ice ages: geological, chemical, and paleontological. Geological evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines , drumlins , valley cutting, and the deposition of till or tillites and glacial erratics . Successive glaciations tend to distort and erase the geological evidence for earlier glaciations, making it difficult to interpret. Furthermore, this evidence
5883-463: The concentrations of greenhouse gases) may alter the climate, while climate change itself can change the atmospheric composition (for example by changing the rate at which weathering removes CO 2 ). Maureen Raymo , William Ruddiman and others propose that the Tibetan and Colorado Plateaus are immense CO 2 "scrubbers" with a capacity to remove enough CO 2 from the global atmosphere to be
5994-487: The contemplation of truth, than with the praise of having discovered it". After some 25 years of work, his Theory of the Earth ; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe was read to meetings of the Royal Society of Edinburgh in two parts, the first by his friend Joseph Black on 7 March 1785, and the second by himself on 4 April 1785. Hutton subsequently read an abstract of his dissertation Concerning
6105-710: The continental ice sheets are the Greenland and Antarctic ice sheets and smaller glaciers such as on Baffin Island . The definition of the Quaternary as beginning 2.58 Ma is based on the formation of the Arctic ice cap . The Antarctic ice sheet began to form earlier, at about 34 Ma, in the mid- Cenozoic ( Eocene-Oligocene Boundary ). The term Late Cenozoic Ice Age is used to include this early phase. Ice ages can be further divided by location and time; for example,
6216-405: The continents and pack ice on the oceans would inhibit both silicate weathering and photosynthesis , which are the two major sinks for CO 2 at present." It has been suggested that the end of this ice age was responsible for the subsequent Ediacaran and Cambrian explosion , though this model is recent and controversial. The Andean-Saharan occurred from 460 to 420 million years ago, during
6327-431: The continents are in positions which block or reduce the flow of warm water from the equator to the poles and thus allow ice sheets to form. The ice sheets increase Earth's reflectivity and thus reduce the absorption of solar radiation. With less radiation absorbed the atmosphere cools; the cooling allows the ice sheets to grow, which further increases reflectivity in a positive feedback loop. The ice age continues until
6438-464: The crystalline salt which was used for dyeing, metalworking and as smelling salts and had been available only from natural sources and had to be imported from Egypt . Hutton owned and rented out properties in Edinburgh, employing a factor to manage this business. Hutton inherited from his father the Berwickshire farms of Slighhouses , a lowland farm which had been in the family since 1713, and
6549-540: The current glaciation, more temperate and more severe periods have occurred. The colder periods are called glacial periods , the warmer periods interglacials , such as the Eemian Stage . There is evidence that similar glacial cycles occurred in previous glaciations, including the Andean-Saharan and the late Paleozoic ice house. The glacial cycles of the late Paleozoic ice house are likely responsible for
6660-617: The deposition of cyclothems . Glacials are characterized by cooler and drier climates over most of Earth and large land and sea ice masses extending outward from the poles. Mountain glaciers in otherwise unglaciated areas extend to lower elevations due to a lower snow line . Sea levels drop due to the removal of large volumes of water above sea level in the icecaps. There is evidence that ocean circulation patterns are disrupted by glaciations. The glacials and interglacials coincide with changes in orbital forcing of climate due to Milankovitch cycles , which are periodic changes in Earth's orbit and
6771-622: The early Proterozoic Eon. Several hundreds of kilometers of the Huronian Supergroup are exposed 10 to 100 kilometers (6 to 62 mi) north of the north shore of Lake Huron, extending from near Sault Ste. Marie to Sudbury, northeast of Lake Huron, with giant layers of now-lithified till beds, dropstones , varves , outwash , and scoured basement rocks. Correlative Huronian deposits have been found near Marquette, Michigan , and correlation has been made with Paleoproterozoic glacial deposits from Western Australia. The Huronian ice age
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#17327765010486882-728: The existence of glacial periods during the Valanginian , Hauterivian , and Aptian stages of the Early Cretaceous. Ice-rafted glacial dropstones indicate that in the Northern Hemisphere , ice sheets may have extended as far south as the Iberian Peninsula during the Hauterivian and Aptian. Although ice sheets largely disappeared from Earth for the rest of the period (potential reports from
6993-408: The first person to suggest drifting sea ice was a cause of the presence of erratic boulders in the Scandinavian and Baltic regions. In 1795, the Scottish philosopher and gentleman naturalist, James Hutton (1726–1797), explained erratic boulders in the Alps by the action of glaciers. Two decades later, in 1818, the Swedish botanist Göran Wahlenberg (1780–1851) published his theory of a glaciation of
7104-450: The following years, Esmark's ideas were discussed and taken over in parts by Swedish, Scottish and German scientists. At the University of Edinburgh Robert Jameson (1774–1854) seemed to be relatively open to Esmark's ideas, as reviewed by Norwegian professor of glaciology Bjørn G. Andersen (1992). Jameson's remarks about ancient glaciers in Scotland were most probably prompted by Esmark. In Germany, Albrecht Reinhard Bernhardi (1797–1849),
7215-417: The geographical distribution of fossils. During a glacial period, cold-adapted organisms spread into lower latitudes, and organisms that prefer warmer conditions become extinct or retreat into lower latitudes. This evidence is also difficult to interpret because it requires: Despite the difficulties, analysis of ice core and ocean sediment cores has provided a credible record of glacials and interglacials over
7326-429: The geologist Sir James Hall of Dunglass . They found the sequence in the cliff below St. Helens, then just to the east at Siccar Point found what Hutton called "a beautiful picture of this junction washed bare by the sea". Playfair later commented about the experience, "the mind seemed to grow giddy by looking so far into the abyss of time". Continuing along the coast, they made more discoveries including sections of
7437-456: The hill farm of Nether Monynut . In the early 1750s he moved to Slighhouses and set about making improvements, introducing farming practices from other parts of Britain and experimenting with plant and animal husbandry. He recorded his ideas and innovations in an unpublished treatise on The Elements of Agriculture . This developed his interest in meteorology and geology. In a 1753 letter he wrote that he had "become very fond of studying
7548-434: The historical warm interglacial period that looks most like the current one and from this have predicted that the next glacial period would usually begin within 1,500 years. They go on to predict that emissions have been so high that it will not. The causes of ice ages are not fully understood for either the large-scale ice age periods or the smaller ebb and flow of glacial–interglacial periods within an ice age. The consensus
7659-409: The land on which we rest is not simple and original, but that it is a composition, and had been formed by the operation of second causes. 2nd, That before the present land was made, there had subsisted a world composed of sea and land, in which were tides and currents, with such operations at the bottom of the sea as now take place. And, Lastly, That while the present land was forming at the bottom of
7770-440: The last 1.5 million years were associated with northward shifts of melting Antarctic icebergs which changed ocean circulation patterns, leading to more CO 2 being pulled out of the atmosphere . The authors suggest that this process may be disrupted in the future as the Southern Ocean will become too warm for the icebergs to travel far enough to trigger these changes. Matthias Kuhle 's geological theory of Ice Age development
7881-422: The last glacial period the sea-level fluctuated 20–30 m as water was sequestered, primarily in the Northern Hemisphere ice sheets. When ice collected and the sea level dropped sufficiently, flow through the Bering Strait (the narrow strait between Siberia and Alaska is about 50 m deep today) was reduced, resulting in increased flow from the North Atlantic. This realigned the thermohaline circulation in
7992-512: The latest Quaternary Ice Age ). Outside these ages, Earth was previously thought to have been ice-free even in high latitudes; such periods are known as greenhouse periods . However, other studies dispute this, finding evidence of occasional glaciations at high latitudes even during apparent greenhouse periods. Rocks from the earliest well-established ice age, called the Huronian , have been dated to around 2.4 to 2.1 billion years ago during
8103-464: The lowering of the Nordic inland ice areas and Tibet due to the weight of the superimposed ice-load, has led to the repeated complete thawing of the inland ice areas. James Hutton James Hutton FRSE ( / ˈ h ʌ t ən / ; 3 June O.S. 1726 – 26 March 1797) was a Scottish geologist , agriculturalist , chemical manufacturer , naturalist and physician . Often referred to as
8214-460: The mechanism allowed species to form varieties better adapted to particular conditions and provided evidence of benevolent design in nature. Studies of Charles Darwin 's notebooks have shown that Darwin arrived separately at the idea of natural selection which he set out in his 1859 book On the Origin of Species , but it has been speculated that he had some half-forgotten memory from his time as
8325-484: The most recent glacial periods, ice cores provide climate proxies , both from the ice itself and from atmospheric samples provided by included bubbles of air. Because water containing lighter isotopes has a lower heat of evaporation , its proportion decreases with warmer conditions. This allows a temperature record to be constructed. This evidence can be confounded, however, by other factors recorded by isotope ratios. The paleontological evidence consists of changes in
8436-526: The motion of tectonic plates resulting in changes in the relative location and amount of continental and oceanic crust on Earth's surface, which affect wind and ocean currents ; variations in solar output ; the orbital dynamics of the Earth–Moon system; the impact of relatively large meteorites and volcanism including eruptions of supervolcanoes . Some of these factors influence each other. For example, changes in Earth's atmospheric composition (especially
8547-695: The mountain on which stands the Kloster Maria Altenburg (monastery). Moosach belonged to the Rentamt [ bar ; de ; es ] of Munich and the Court of Swabia of the Electorate of Bavaria . In the course of administrative reforms in Bavaria, the current community came into being with the community edict of 1818. Ice age An ice age is a long period of reduction in
8658-459: The names Riss (180,000–130,000 years bp ) and Würm (70,000–10,000 years bp) refer specifically to glaciation in the Alpine region . The maximum extent of the ice is not maintained for the full interval. The scouring action of each glaciation tends to remove most of the evidence of prior ice sheets almost completely, except in regions where the later sheet does not achieve full coverage. Within
8769-562: The natural history of the earth, and which I had been long looking for in vain." That year, he found the same sequence in Teviotdale . In the Spring of 1788 he set off with John Playfair to the Berwickshire coast and found more examples of this sequence in the valleys of the Tour and Pease Burns near Cockburnspath . They then took a boat trip from Dunglass Burn east along the coast with
8880-560: The ocean, the former land maintained plants and animals; at least the sea was then inhabited by animals, in a similar manner as it is at present. Hence we are led to conclude, that the greater part of our land, if not the whole had been produced by operations natural to this globe; but that in order to make this land a permanent body, resisting the operations of the waters, two things had been required; 1st, The consolidation of masses formed by collections of loose or incoherent materials; 2ndly, The elevation of those consolidated masses from
8991-521: The past few million years. These also confirm the linkage between ice ages and continental crust phenomena such as glacial moraines, drumlins, and glacial erratics. Hence the continental crust phenomena are accepted as good evidence of earlier ice ages when they are found in layers created much earlier than the time range for which ice cores and ocean sediment cores are available. There have been at least five major ice ages in Earth's history (the Huronian , Cryogenian , Andean-Saharan , late Paleozoic , and
9102-447: The past", and Charles Lyell memorably rephrased in the 1830s as "the present is the key to the past". Hutton's 1788 paper concludes; "The result, therefore, of our present enquiry is, that we find no vestige of a beginning,–no prospect of an end." His memorably phrased closing statement has long been celebrated. (It was quoted in the 1989 song " No Control " by songwriter and professor Greg Graffin . ) Following criticism, especially
9213-427: The prose of Principles of Knowledge was so obscure that it also impeded the acceptance of Hutton's geological theories. Restatements of his geological ideas (though not his thoughts on evolution) by John Playfair in 1802 and then Charles Lyell in the 1830s popularised the concept of an infinitely repeating cycle, though Lyell tended to dismiss Hutton's views as giving too much credence to catastrophic changes. It
9324-567: The reduction in weathering causes an increase in the greenhouse effect . There are three main contributors from the layout of the continents that obstruct the movement of warm water to the poles: Since today's Earth has a continent over the South Pole and an almost land-locked ocean over the North Pole, geologists believe that Earth will continue to experience glacial periods in the geologically near future. Some scientists believe that
9435-419: The relationship between the rock layers. On the 1787 trip to the Isle of Arran he found his first example of Hutton's Unconformity to the north of Newton Point near Lochranza , but the limited view meant that the condition of the underlying strata was not clear enough for him, and he incorrectly thought that the strata were conformable at a depth below the exposed outcrop. Later in 1787 Hutton noted what
9546-469: The role of weathering). Greenhouse gas levels may also have been affected by other factors which have been proposed as causes of ice ages, such as the movement of continents and volcanism. The Snowball Earth hypothesis maintains that the severe freezing in the late Proterozoic was ended by an increase in CO 2 levels in the atmosphere, mainly from volcanoes, and some supporters of Snowball Earth argue that it
9657-500: The spread of ice sheets in the Northern Hemisphere began. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000- and 100,000-year time scales called glacial periods , glacials or glacial advances, and interglacial periods, interglacials or glacial retreats. Earth is currently in an interglacial, and the last glacial period ended about 11,700 years ago. All that remains of
9768-557: The summer of 1835 he made some excursions to the Bavarian Alps. Schimper came to the conclusion that ice must have been the means of transport for the boulders in the alpine upland. In the winter of 1835–36 he held some lectures in Munich. Schimper then assumed that there must have been global times of obliteration ("Verödungszeiten") with a cold climate and frozen water. Schimper spent the summer months of 1836 at Devens, near Bex, in
9879-541: The surface of the earth, and was looking with anxious curiosity into every pit or ditch or bed of a river that fell in his way". Clearing and draining his farm provided ample opportunities. The mathematician John Playfair described Hutton as having noticed that "a vast proportion of the present rocks are composed of materials afforded by the destruction of bodies, animal, vegetable and mineral, of more ancient formation". His theoretical ideas began to come together in 1760. While his farming activities continued, in 1764 he went on
9990-449: The sustenance of the animal... the same principle [would] change the qualities of the animal, and.. produce a race of well scented hounds, instead of those who catch their prey by swiftness". The same "principle of variation" would influence "every species of plant, whether growing in a forest or a meadow". He came to his ideas as the result of experiments in plant and animal breeding , some of which he outlined in an unpublished manuscript,
10101-629: The temperature of Earth 's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers . Earth's climate alternates between ice ages, and greenhouse periods during which there are no glaciers on the planet. Earth is currently in the ice age called Quaternary glaciation . Individual pulses of cold climate within an ice age are termed glacial periods ( glacials, glaciations, glacial stages, stadials, stades , or colloquially, ice ages ), and intermittent warm periods within an ice age are called interglacials or interstadials . In glaciology ,
10212-481: The temperatures over land by increased albedo as noted above. Furthermore, under this hypothesis the lack of oceanic pack ice allows increased exchange of waters between the Arctic and the North Atlantic Oceans, warming the Arctic and cooling the North Atlantic. (Current projected consequences of global warming include a brief ice-free Arctic Ocean period by 2050 .) Additional fresh water flowing into
10323-477: The term ice age is defined by the presence of extensive ice sheets in the northern and southern hemispheres. By this definition, the current Holocene period is an interglacial period of an ice age. The accumulation of anthropogenic greenhouse gases is projected to delay the next glacial period. In 1742, Pierre Martel (1706–1767), an engineer and geographer living in Geneva , visited the valley of Chamonix in
10434-444: The then-popular Neptunist theories of the German geologist Abraham Gottlob Werner , that all rocks had precipitated out of a single enormous flood. Hutton proposed that the interior of the Earth was hot, and that this heat was the engine which drove the creation of new rock: land was eroded by air and water and deposited as layers in the sea; heat then consolidated the sediment into stone, and uplifted it into new lands. This theory
10545-547: The tilt of Earth's rotational axis. Earth has been in an interglacial period known as the Holocene for around 11,700 years, and an article in Nature in 2004 argues that it might be most analogous to a previous interglacial that lasted 28,000 years. Predicted changes in orbital forcing suggest that the next glacial period would begin at least 50,000 years from now. Moreover, anthropogenic forcing from increased greenhouse gases
10656-457: The vertical beds showing strong ripple marks which gave Hutton "great satisfaction" as a confirmation of his supposition that these beds had been laid horizontally in water. He also found conglomerate at altitudes that demonstrated the extent of erosion of the strata, and said of this that "we never should have dreamed of meeting with what we now perceived". Hutton reasoned that there must have been innumerable cycles, each involving deposition on
10767-504: The works. At this time he is listed as living on Bernard Street in Leith . In 1777 he published a pamphlet on Considerations on the Nature, Quality and Distinctions of Coal and Culm which successfully helped to obtain relief from excise duty on carrying small coal. In 1783, he was a joint founder of the Royal Society of Edinburgh . From 1791 Hutton suffered extreme pain from stones in
10878-552: The world. When the Bavarian naturalist Ernst von Bibra (1806–1878) visited the Chilean Andes in 1849–1850, the natives attributed fossil moraines to the former action of glaciers. Meanwhile, European scholars had begun to wonder what had caused the dispersal of erratic material. From the middle of the 18th century, some discussed ice as a means of transport. The Swedish mining expert Daniel Tilas (1712–1772) was, in 1742,
10989-525: Was Professor Frederik Winter, who was not only a professor at Leiden University, but also court physician to the Stadholder. The Latin manuscript of Hutton's dissertation also contained 92 theses, two of which were successfully defended in public by James Hutton on 3 September 1749. On 12 September 1749, James Hutton obtained his doctorate in medicine from Leiden University with a physico-medical thesis entitled Sanguine et Circulatione Microcosmi. The thesis
11100-625: Was caused by the elimination of atmospheric methane , a greenhouse gas , during the Great Oxygenation Event . The next well-documented ice age, and probably the most severe of the last billion years, occurred from 720 to 630 million years ago (the Cryogenian period) and may have produced a Snowball Earth in which glacial ice sheets reached the equator, possibly being ended by the accumulation of greenhouse gases such as CO 2 produced by volcanoes. "The presence of ice on
11211-429: Was caused in the first place by a reduction in atmospheric CO 2 . The hypothesis also warns of future Snowball Earths. In 2009, further evidence was provided that changes in solar insolation provide the initial trigger for Earth to warm after an Ice Age, with secondary factors like increases in greenhouse gases accounting for the magnitude of the change. The geological record appears to show that ice ages start when
11322-455: Was difficult to date exactly; early theories assumed that the glacials were short compared to the long interglacials. The advent of sediment and ice cores revealed the true situation: glacials are long, interglacials short. It took some time for the current theory to be worked out. The chemical evidence mainly consists of variations in the ratios of isotopes in fossils present in sediments and sedimentary rocks and ocean sediment cores. For
11433-477: Was dubbed " Plutonist " in contrast to the flood-oriented theory. As well as combating the Neptunists, he also accepted the growing consensus on the concept of deep time for scientific purposes. Rather than accepting that the earth was no more than a few thousand years old, he maintained that the Earth must be much older , with a history extending indefinitely into the distant past. His main line of argument
11544-552: Was entitled An Investigation of the Principles of Knowledge and of the Progress of Reason, from Sense to Science and Philosophy when the third volume was completed in 1794. Its 2,138 pages prompted Playfair to remark that "The great size of the book, and the obscurity which may justly be objected to many parts of it, have probably prevented it from being received as it deserves." His new theories placed him into opposition with
11655-459: Was found for over a century (Rudwick, Bursting the Limits of Time ). Hutton's idea of infinite cycles with humans present throughout is quite different from modern geology, with a definite time of formation and directional change through time, but his supporting evidence for the long-term effects of geological processes was valuable in the development of historical geology. It has been claimed that
11766-566: Was invited by the Duke of Atholl to his hunting lodge, Forest Lodge. The exposures at the Dail-an-eas Bridge demonstrated to him that granite formed from the cooling of molten rock rather than it precipitating out of water as others at the time believed, and therefore the granite must be younger than the schists. Hutton presented his theory of the earth on 4 March and 7 April 1785, at the Royal Society of Edinburgh. He went on to find
11877-405: Was not merely the earth to which Hutton directed his attention. He had long studied the changes of the atmosphere . The same volume in which his Theory of the Earth appeared contained also a Theory of Rain . He contended that the amount of moisture which the air can retain in solution increases with temperature, and, therefore, that on the mixture of two masses of air of different temperatures
11988-458: Was particularly interested in mathematics and chemistry , then when he was 14 he attended the University of Edinburgh as a "student of humanity", studying the classics . He was apprenticed to the lawyer George Chalmers WS when he was 17, but took more interest in chemical experiments than legal work. At the age of 18, he became a physician's assistant, and attended lectures in medicine at
12099-412: Was printed by Wilhelmus Boot, book printer in Leiden. It is believed that James Hutton returned to Britain shortly after his promotion. After his degree Hutton went to London, then in mid-1750 returned to Edinburgh and resumed chemical experiments with close friend, John Davie. Their work on production of sal ammoniac from soot led to their partnership in a profitable chemical works, manufacturing
12210-526: Was suggested by the existence of an ice sheet covering the Tibetan Plateau during the Ice Ages ( Last Glacial Maximum ?). According to Kuhle, the plate-tectonic uplift of Tibet past the snow-line has led to a surface of c. 2,400,000 square kilometres (930,000 sq mi) changing from bare land to ice with a 70% greater albedo . The reflection of energy into space resulted in a global cooling, triggering
12321-439: Was that the tremendous displacements and changes he was seeing did not happen in a short period of time by means of catastrophe, but that processes still happening on the Earth in the present day had caused them. As these processes were very gradual, the Earth needed to be ancient, to allow time for the changes. Contemporary investigations had shown that the geologic record required vast time, but no good way of assigning actual years
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