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Crescentic Gouge
In glacial geology, a chatter mark is a wedge-shaped mark (usually of a series of such marks) left by chipping of a bedrock surface by rock fragments carried in the base of a glacier ( glacial plucking). Marks tend to be crescent-shaped and oriented at right angles to the direction of ice movement.Marshak, Stephen, 2009, Essentials of Geology, W. W. Norton & Company, 3rd ed. There are three different types of chatter marks. The crescentic gouge is an upstream concave that is made by the removal of a piece of rock. The crescentic fracture is a downstream concave that is also made by the removal of rock. The lunate fracture is also a downstream concave made without the removal of rock. See also * Glacial polish *Glacial striation Glacial striations or striae are scratches or gouges cut into bedrock by glacial abrasion. These scratches and gouges were first recognized as the result of a moving glacier in the late 18th century when Swiss alpinists first associated them ... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lac Beauchamp Chatter Marks
Lac may refer to: Places Africa * Lac Region, a district in Chad * Lac Prefecture, a district in Chad America * Rivière du Lac, a tributary of the Montmorency River, in Capitale-Nationale, Quebec, Canada Europe * Laç, a city in Albania * Lac, a village in Voloiac Commune, Mehedinţi County, Romania * Lac district, a district in the canton of Fribourg, Switzerland * Lancing railway station, a railway station in Sussex, England (station code: LAC) Elsewhere * Lac, a standard astronomical constellation abbreviation of Lacerta * Latin America and the Caribbean or LAC, a regional definition by the United Nations Other uses * Lac (resin), a resinous substance produced by insects **Shellac, the processed form of this resin * ''Lac'', French for lake (body of water) * ''lác'', an element in Anglo-Saxon names meaning "fight, play" *Lac, a character in Arthurian romance, father of Erec * LAC, the ICAO operator designator for Lockheed Corporation (Lockheed Aircraft Corporation), Unit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glaciology
Glaciology (; ) is the scientific study of glaciers, or, more generally, ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on people includes the fields of human geography and anthropology. The discoveries of water ice on the Moon, Mars, Europa (moon), Europa and Pluto add an extraterrestrial component to the field, which is referred to as "astroglaciology". Overview A glacier is a persistent body of dense ice, a form of rock) formed from snow falling and accumulating over a long period of time; glaciers move very slowly, either descending from high mountains, as in valley glaciers, or moving outward from centers of accumulation, as in continental glaciers. Areas of study within glaciology include glacial history and the reconstruction of past glaciation. A glaciologist is a person ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bedrock
In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of bedrock is often called an outcrop. The various kinds of broken and weathered rock material, such as soil and subsoil, that may overlie the bedrock are known as regolith. Engineering geology The surface of the bedrock beneath the soil cover (regolith) is also known as ''rockhead'' in engineering geology, and its identification by digging, drilling or geophysical methods is an important task in most civil engineering projects. Superficial deposits can be very thick, such that the bedrock lies hundreds of meters below the surface. Weathering of bedrock Exposed bedrock experiences weathering, which may be physical or chemical, and which alters the structure of the rock to leave it susceptible to erosion. Bedrock may also experience subsur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacier
A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land“Glacier, N., Pronunciation.” Oxford English Dictionary, Oxford UP, June 2024, https://doi.org/10.1093/OED/7553486115. Accessed 25 Jan. 2025. and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on ever ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Plucking
Plucking, also referred to as ''quarrying'', is a glacial phenomenon that is responsible for the weathering and erosion of pieces of bedrock, especially large "joint blocks". This occurs in a type of glacier called a "valley glacier". As a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock. The freezing and thawing action of the ice enlarges, widens, or causes further cracks in the bedrock as it changes volume across the ice/water phase transition (a form of hydraulic wedging), gradually loosening the rock between the joints. This produces large chunks of rock called joint blocks. Eventually these joint blocks come loose and become trapped in the glacier. In this way, plucking has been linked to regelation. Rocks of all sizes can become trapped in the bottom of the glacier. Joint blocks up to three meters have been "plucked" and transported. These entrained rock fragments can also cause abrasion along ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crescent
A crescent shape (, ) is a symbol or emblem used to represent the lunar phase (as it appears in the northern hemisphere) in the first quarter (the "sickle moon"), or by extension a symbol representing the Moon itself. In Hindu iconography, Hindu Iconography, Shiva is often shown wearing a crescent moon on his head, symbolising his control over time, as well as his attributes of both creation and destruction. It is used as the astrological symbol for Moon (astrology), the Moon, and hence as the alchemical symbol for silver. It was also the emblem of Diana (mythology), Diana/Artemis, and hence represented virginity. In veneration of Mary in the Catholic Church, it is associated with Mary, mother of Jesus. From its use as roof finial in Ottoman architecture, Ottoman mosques, it has also become associated with Islam, and the crescent was introduced as Religious symbolism in the United States military#Muslim, chaplain badge for Muslim United States military chaplains in 1993.On Dece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunate
Lunate is a crescent or moon-shaped microlith. In the specialized terminology of lithic reduction, a lunate flake is a small, crescent-shaped lithic flake, flake removed from a stone tool during the process of pressure flaking. In the Natufian culture, Natufian period, a lunate was a small crescent-shaped stone tool that was sometimes used to harvest grasses. In archaeology a lunate is a small stone artifact, that has a sharpened straight edge and a blunt crescent shaped back. The word originates from the Latin word ''lunatus'' which means to bend like a crescent, and from luna meaning moon in Latin. A lunate object can be typically used as a decorative piece or as a stone tool. Israeli lunate In the earlier findings of Epipaleolithic lunate in the Natufian, Harifian, and Negev Kebaran periods in Israel, they were roughly 10–40 mm long and were formed on small blades or bladelets. While the later findings Natufian and Harifian range of lengths varied then between 9&nbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Polish
Glacial polish is a feature of rock surfaces that is typically associated with Glacial striation, glacial striations. This phenomenon is where glaciers have passed over bedrock, typically granite or other hard igneous rock, igneous or metamorphic rock. Moving ice will carry pebbles and sand grains removed from upper levels, grinding a smooth or grooved surface upon the underlying rock. The presence of such polish indicates that the glaciation was relatively recent (in geologic time scale) or was subsequently protected by deposition, as such polish will be subsequently lost due to weathering processes (such as Exfoliation joint, exfoliation). Considering some samples of glacial polish from sites such as Yosemite National Park, scientists have discovered that they developed thin coatings composed of tiny rock particles rather than rocks just being worn down solely from the movement of the glaciers. Over time, this coating contributes to the smoothness of the rocks. This coating al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Striation
Glacial striations or striae are scratches or gouges cut into bedrock by glacial abrasion. These scratches and gouges were first recognized as the result of a moving glacier in the late 18th century when Swiss alpinists first associated them with moving glaciers. They also noted that if they were visible today that the glaciers must also be receding. Glacial striations are usually multiple, straight, and parallel, representing the movement of the glacier using rock fragments and sand grains, embedded in the base of the glacier, as cutting tools. Large amounts of coarse gravel and boulders carried along underneath the glacier provide the abrasive power to cut trough-like ''glacial grooves''. Finer sediments also in the base of the moving glacier further scour and polish the bedrock surface, forming a ''glacial pavement''. Ice itself is not a hard enough material to change the shape of rock but because the ice has rock embedded in the basal surface it can effectively abrade the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
