Glacial erratic in the context of "Flood geology"

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⭐ Core Definition: Glacial erratic

A glacial erratic is a glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word errare ("to wander"), are carried by glacial ice, often over distances of hundreds of kilometres. Erratics can range in size from pebbles to large boulders such as Big Rock (16,500 metric tons) in Alberta.

Geologists identify erratics by studying the rocks surrounding the position of the erratic and the composition of the erratic itself. Erratics are significant because:

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👉 Glacial erratic in the context of Flood geology

Flood geology (also creation geology or diluvial geology) is a pseudoscientific attempt to interpret and reconcile geological features of the Earth in accordance with a literal belief in the Genesis flood narrative, the flood myth in the Hebrew Bible. In the early 19th century, diluvial geologists hypothesized that specific surface features provided evidence of a worldwide flood which had followed earlier geological eras; after further investigation they agreed that these features resulted from local floods or from glaciers. In the 20th century, young-Earth creationists revived flood geology as an overarching concept in their opposition to evolution, assuming a recent six-day Creation and cataclysmic geological changes during the biblical flood, and incorporating creationist explanations of the sequences of rock strata.

In the early stages of development of the science of geology, fossils were interpreted as evidence of past flooding. The "theories of the Earth" of the 17th century proposed mechanisms based on natural laws, within a timescale set by the Ussher chronology. As modern geology developed, geologists found evidence of an ancient Earth and evidence inconsistent with the notion that the Earth had developed in a series of cataclysms, like the Genesis flood. In early 19th-century Britain, "diluvialism" attributed landforms and surface features (such as beds of gravel and erratic boulders) to the destructive effects of this supposed global deluge, but by 1830 geologists increasingly found that the evidence supported only relatively local floods. So-called scriptural geologists attempted to give primacy to literal biblical explanations, but they lacked a background in geology and were marginalised by the scientific community, as well as having little influence in the churches.

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Glacial erratic in the context of Charles Lyell

Sir Charles Lyell, 1st Baronet, FRS (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known today for his association with Charles Darwin and as the author of Principles of Geology (1830–33), which presented to a wide public audience the idea that the earth was shaped by the same natural processes still in operation today, operating at similar intensities. The philosopher William Whewell dubbed this gradualistic view "uniformitarianism" and contrasted it with catastrophism, which had been championed by Georges Cuvier and was better accepted in Europe. The combination of evidence and eloquence in Principles convinced a wide range of readers of the significance of "deep time" for understanding the earth and environment.

Lyell's scientific contributions included a pioneering explanation of climate change, in which shifting boundaries between oceans and continents could be used to explain long-term variations in temperature and rainfall. Lyell also gave influential explanations of earthquakes and developed the theory of gradual "backed up-building" of volcanoes. In stratigraphy his division of the Tertiary period into the Pliocene, Miocene, and Eocene was highly influential. He incorrectly conjectured that icebergs were the impetus behind the transport of glacial erratics, and that silty loess deposits might have settled out of flood waters. His creation of a separate period for human history, entitled the 'Recent', is widely cited as providing the foundations for the modern discussion of the Anthropocene.

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Glacial erratic in the context of U-shaped valley

U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight sides and a flat or rounded bottom (by contrast, valleys carved by rivers tend to be V-shaped in cross-section). Glaciated valleys are formed when a glacier travels across and down a slope, carving the valley by the action of scouring. When the ice recedes or thaws, the valley remains, often littered with small boulders that were transported within the ice, called glacial till or glacial erratic.

Examples of U-shaped valleys are found in mountainous regions throughout the world including the Andes, Alps, Caucasus Mountains, Himalaya, Rocky Mountains, New Zealand and the Scandinavian Mountains. They are found also in other major European mountains including the Carpathian Mountains, the Pyrenees, the Rila and Pirin mountains in Bulgaria, and the Scottish Highlands. A classic glacial trough is in Glacier National Park in Montana, USA in which the St. Mary River runs. Another well-known U-shaped valley is the Nant Ffrancon valley in Snowdonia, Wales.

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Glacial erratic in the context of Monolith

A monolith is a geological feature consisting of a single massive stone or rock, such as some mountains. Erosion usually exposes the geological formations, which are often made of very hard and solid igneous or metamorphic rock. Some monoliths are volcanic plugs, solidified lava filling the vent of an extinct volcano.

In architecture, the term has considerable overlap with megalith, which is normally used for prehistory, and may be used in the contexts of rock-cut architecture that remains attached to solid rock, as in monolithic church, or for exceptionally large stones such as obelisks, statues, monolithic columns or large architraves, that may have been moved a considerable distance after quarrying. It may also be used of large glacial erratics moved by natural forces.

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Glacial erratic in the context of North Shore (Long Island)

The North Shore of Long Island is the area along the northern coast of New York's Long Island bordering Long Island Sound. Known for its extreme wealth and lavish estates, the North Shore exploded into affluence at the turn of the 20th century, earning it the nickname the Gold Coast. Historically, this term refers to the affluent coastline neighborhoods of the towns of North Hempstead (such as Great Neck and Port Washington), Glen Cove, and Oyster Bay in Nassau County and Huntington in Suffolk County. Some definitions may also include the parts of Smithtown that face the Sound. The region is also largely coextensive with the Gold Coast region of Long Island, though this region excludes Smithtown, as the easternmost Gold Coast mansion is the Geissler Estate, located just west of Indian Hills Country Club in the Fort Salonga section of Huntington.

Being a remnant of the Harbor Hill Moraine the North Shore is somewhat hilly, and its beaches are more rocky than those on the flat, sandy outwash plain of the South Shore along the Atlantic Ocean. Large boulders known as glacial erratics are scattered across the area.

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Glacial erratic in the context of Drift (geology)

In geology, drift is a name for all sediment (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by glacial meltwater. Drift is often subdivided into unstratified (unsorted) drift (glacial till) that forms moraines and stratified drift (glaciolacustrine and fluvioglacial sediments) that accumulates as stratified and sorted sediments in the form of outwash plains, eskers, kames, varves, and so forth. The term drift clay is a synonym for boulder clay. Both are archaic terms for glacial tills with a fine-grained matrix.

In the United Kingdom, drift is also applied as a general term for all surficial, unconsolidated, rock debris and sediment that is moved from one place to accumulate in another and mapped separately or otherwise differentiated from underlying bedrock. In this usage, drift includes a wide variety of deposits, e.g. loess, glacial till, river deposits, colluvium, and so forth, of Quaternary age. However, this term is most commonly used to specifically describe glacial deposits.

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Glacial erratic in the context of Geotope

A geotope is the geological component of the abiotic matrix present in an ecotope. Example geotopes might be an exposed outcrop of rocks, an erratic boulder, a grotto or ravine, a cave, an old stone wall marking a property boundary, and so forth.

It is a loanword from German (Geotop) in the study of ecology and might be the model for many other similar words coined by analogy. As the prototype, it has enjoyed wider currency than many of the other words modelled on it, including physiotope, with which it is used synonymously. But the geotope is properly the rocks and not the whole lay of the land (which would be the physiotope).

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