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Arctomys Formation
The Arctomys Formation is a stratigraphic unit of late Middle Cambrian age. It is present on the western edge of the Western Canada Sedimentary Basin in the Canadian Rockies of Alberta and British Columbia. It was named for Arctomys Peak near Mount Erasmus in Banff National Park by Charles Doolittle Walcott in 1920. Outcrops of the Arctomys can be seen in Banff and Jasper National Parks. Lithology and deposition The Arctomys was deposited along the western shoreline of the North American Craton during late Middle Cambrian time.Aitken, J.D. 1966. Middle Cambrian to Middle Ordovician cyclic sedimentation, southern Rocky Mountains of Alberta. Bulletin of Canadian Petroleum Geology, vol. 14, no. 6, p. 405-441. It consists primarily of red, grey, and green platy shale. Sedimentary structures include mudcracks, ripple marks, and casts of salt crystals. Environments of deposition may have included shallow lakes, lagoons, and sheet-flood deposits on dry mud flats.Spencer, R.J. and Demicc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratigraphic Unit
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Outcrop
An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by soil and vegetation and cannot be seen or examined closely. However, in places where the overlying cover is removed through erosion or tectonic uplift, the rock may be exposed, or ''crop out''. Such exposure will happen most frequently in areas where erosion is rapid and exceeds the weathering rate such as on steep hillsides, mountain ridges and tops, river banks, and tectonically active areas. In Finland, glacial erosion during the last glacial maximum (ca. 11000 BC), followed by scouring by sea waves, followed by isostatic uplift has produced many smooth coastal and littoral outcrops. Bedrock and superficial deposits may also be exposed at the Earth's surface due to human excavations such as quarrying and bui ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian System Of North America
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' ( Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian British Columbia
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Robson
Mount Robson is the most prominent mountain in North America's Rocky Mountain range; it is also the highest point in the Canadian Rockies. The mountain is located entirely within Mount Robson Provincial Park of British Columbia, and is part of the Rainbow Range. Mount Robson is the second highest peak entirely in British Columbia, behind Mount Waddington in the Coast Range. The south face of Mount Robson is clearly visible from the Yellowhead Highway (Highway 16), and is commonly photographed along this route. Mount Robson was likely named after Colin Robertson, who worked for both the North West Company and the Hudson's Bay Company at various times in the early 19th century, though there was confusion over the name as many assumed it to have been named for John Robson, an early premier of British Columbia. The Texqakallt, a Secwepemc people and the earliest known inhabitants of the area, call it (striped rock), spelled in Dawson 1891 as , ''The Mountain of the Spi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Man Mountain
White Man Mountain is located on the Continental Divide between Alberta and British Columbia. It was named by George Mercer Dawson in 1884 and is Alberta's 92nd most prominent mountain. See also * List of peaks on the Alberta–British Columbia border * Mountains of Alberta * Mountains of British Columbia British Columbia is the westernmost province of Canada, bordered by the Pacific Ocean. With an area of it is Canada's third-largest province. The province is almost four times the size of the United Kingdom and larger than every United States ... References External links * White Man Mountain White Man Mountain Canadian Rockies Kootenay Land District {{EastKootenay-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halite
Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on inclusion of other materials, impurities, and structural or isotopic abnormalities in the crystals. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates. The name ''halite'' is derived from the Ancient Greek word for "salt", ἅλς (''háls''). Occurrence Halite dominantly occurs within sedimentary rocks where it has formed from the evaporation of seawater or salty lake water. Vast beds of sedimentary evaporite minerals, including halite, can result from the drying up of enclosed lakes and restricted seas. Such salt beds may be hundreds of meters thick and underlie broad areas. Halite occurs at the surface today in playas in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ripple Marks
In geology, ripple marks are sedimentary structures (i.e., bedforms of the lower flow regime) and indicate agitation by water ( current or waves) or wind. Defining ripple cross-laminae and asymmetric ripples * ''Current ripple marks'', ''unidirectional ripples'', or ''asymmetrical ripple marks'' are asymmetrical in profile, with a gentle up-current slope and a steeper down-current slope. The down-current slope is the angle of repose, which depends on the shape of the sediment. These commonly form in fluvial and aeolian depositional environments, and are a signifier of the lower part of the Lower Flow Regime. * Ripple cross-laminae forms when deposition takes place during migration of current or wave ripples. A series of cross-laminae are produced by superimposing migrating ripples. The ripples form lateral to one another, such that the crests of vertically succeeding laminae are out of phase and appear to be advancing upslope. This process results in cross-bedded ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mudcrack
Mudcracks (also known as mud cracks, desiccation cracks or cracked mud) are sedimentary structures formed as muddy sediment dries and contracts.Jackson, J.A., 1997, ''Glossary of Geology'' (4th ed.), American Geological Institute, Alexandria, VA, 769 p.Stow, D.A., 2005, ''Sedimentary Rocks in the Field'', Academic Press, London, 320 p. Crack formation also occurs in clay-bearing soils as a result of a reduction in water content. Formation of mudcrack Naturally forming mudcracks start as wet, muddy sediment dries up and contracts. A strain is developed because the top layer shrinks while the material below stays the same size. When this strain becomes large enough, channel cracks form in the dried-up surface to relieve the strain. Individual cracks spread and join up, forming a polygonal, interconnected network of forms called "tesselations." If the strain continues to build the polygon start to curled upward. This characteristic can be used in geology to understand the origina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedimentary Structure
Sedimentary structures include all kinds of features in sediments and sedimentary rocks, formed at the time of deposition. Sediments and sedimentary rocks are characterized by bedding, which occurs when layers of sediment, with different particle sizes are deposited on top of each other. These beds range from millimeters to centimeters thick and can even go to meters or multiple meters thick. Sedimentary structures such as cross-bedding, graded bedding, and ripple marks are utilized in stratigraphic studies to indicate original position of strata in geologically complex terrains and understand the depositional environment of the sediment. Flow structures There are two kinds of flow structures: bidirectional (multiple directions, back-and-forth) and unidirectional. Flow regimes in single-direction (typically fluvial) flow, which at varying speeds and velocities produce different structures, are called bedforms. In the ''lower flow regime'', the natural progression is from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shale
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.Blatt, Harvey and Robert J. Tracy (1996) ''Petrology: Igneous, Sedimentary and Metamorphic'', 2nd ed., Freeman, pp. 281–292 Shale is characterized by its tendency to split into thin layers ( laminae) less than one centimeter in thickness. This property is called '' fissility''. Shale is the most common sedimentary rock. The term ''shale'' is sometimes applied more broadly, as essentially a synonym for mudrock, rather than in the more narrow sense of clay-rich fissile mudrock. Texture Shale typically exhibits varying degrees of fissility. Because of the parallel orientation of clay mineral flakes in shale, it breaks into thin layers, often splintery and usually parallel to the otherwise indistinguishable bed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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