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Ravenscrag Formation
The Ravenscrag Formation is a stratigraphic unit of early Paleocene age in the Western Canada Sedimentary Basin. It was named for the settlement of Ravenscrag, Saskatchewan, and was first described from outcrops at Ravenscrag Butte near the Frenchman River by N.B. Davis in 1918.Davis, N.B., 1918. Report on the clay resources of southern Saskatchewan; Canada, Department of Mines, Mines Branch, Report 468, 93 p. The Ravenscrag Formation includes a wide range of vertebrate and plant fossils, as well as economically significant coal seams and clay deposits. Lithology The Ravenscrag Formation is an eastward-thickening wedge of sediments. It is composed primarily of buff, grey and white silty claystone, with mudstone, siltstone, sandstone, and several significant coal seams. Glass, D.J., editor, 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada, p. 974. Canadian Society of Petroleum Geologists, Calgary, Alberta, 1423 p. on CD-ROM, . These sediments were deposited in flood ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay particles, but become hard, brittle and non–plastic upon drying or firing. Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clay is the oldest known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery. Some of the earliest pottery shards have been dated to around 14,000 BC, and clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtering. Between one-half and two-thirds of the world's population live or work in buildings made with clay, often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saskatchewan
Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the United States, U.S. states of Montana and North Dakota. Saskatchewan and Alberta are the only landlocked provinces of Canada. In 2022, Saskatchewan's population was estimated at 1,205,119. Nearly 10% of Saskatchewan’s total area of is fresh water, mostly rivers, reservoirs and List of lakes in Saskatchewan, lakes. Residents primarily live in the southern prairie half of the province, while the northern half is mostly forested and sparsely populated. Roughly half live in the province's largest city Saskatoon or the provincial capital Regina, Saskatchewan, Regina. Other notable cities include Prince Albert, Saskatchewan, Prince Albert, Moose Jaw, Yorkton, Swift Current, North Battleford, Melfort, Saskatchewan, Melfort, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiffanian
The Tiffanian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 60,200,000 to 56,800,000 years BP lasting . It is usually considered to overlap the Selandian and Thanetian within the Paleocene. The Tiffanian is preceded by the Torrejonian and followed by the Clarkforkian NALMA stages. Substages The Tiffanian is considered to contain the following substages: *Ti6: Lower boundary source of the base of the Tiffanian (approximate). *Ti5 Lower boundary source of the base of the Tiffanian (approximate) and upper boundary source of the base of the Clarkforkian (approximate). *Ti4: Lower boundary source of the base of the Tiffanian (approximate) and upper boundary source of the base of the Clarkforkian (approximate). *Ti3: Lower boundary source of the base of the Tiffanian (approximate) and upper boundary source of the base of the Clarkforkian (approximate). *Ti2: Lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Puercan
The Puercan North American Stage on the geologic timescale is the North American faunal stage In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convent ... according to the North American Land Mammal Ages chronology (NALMA), spanning the interval from 66,000,000 to 63,300,000 years Before Present, BP lasting . It is usually considered to be within the Paleocene. The Puercan directly follows the Lancian NALMA, with the K-Pg boundary and K-Pg mass extinction at 66 MYA representing the boundary between the two. The Puercan is followed by the Torrejonian NALMA stage. Puercan age fossils, from the Great Divide Basin, Wyoming, include three newly identified condylarth members of the Periptychidae; ''Miniconus, Miniconus jeanninae, Conacodon, Conacodon hettingeri, Beornus, Beornus honeyi'' Subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Land Mammal Age
The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when referring to the rock strata of that age) and were established using geographic place names where fossil materials were obtained. System The North American land-mammal-age system was formalized in 1941 as a series of provincial land-mammal ages. The system was the standard for correlations in the terrestrial Cenozoic record of North America and was the source for similar time scales dealing with other continents. The system was revised into a formal chronostratigraphic system. This approach is nominally justified by international stratigraphic codes; it holds that first appearances of individual species in particular sections are the only valid basis for naming and defining the land-mammal ages. The basic unit of measure is the first/last bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iridium Anomaly
The term iridium anomaly commonly refers to an unusual abundance of the chemical element iridium in a layer of rock strata at the Cretaceous–Paleogene (K–Pg) boundary. The unusually high concentration of a rare metal like iridium is often taken as evidence for an extraterrestrial impact event. Anomaly characteristics The type locality of this iridium anomaly is near Raton, New Mexico. Iridium is a very rare element in the Earth's crust, but is found in anomalously high concentrations (around 100 times greater than normal) in a thin worldwide layer of clay marking the boundary between the Cretaceous and Paleogene periods, 66 million years ago. This boundary is marked by a major extinction event, including that of the dinosaurs along with about 70% of all other species. The clay layer also contains small grains of shocked quartz and, in some places, small weathered glass beads thought to be tektites. Meteorite impact theory A team consisting of the physicist Luis Alvarez, h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock Stratum, strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Biology'', 8th ed., Oxford University Press, 2019. The primary objective of biostratigraphy is ''correlation'', demonstrating that a particular Horizon (geology), horizon in one geological section represents the same period of time as another horizon at a different section. Fossils within these strata are useful because sediments of the same age can look completely different, due to local variations in the Sedimentary depositional environment, sedimentary environment. For example, one section might have been made up of clays and marls, while another has more chalky limestones. However, if the fossil species recorded are similar, the two sediments are likely to have been laid down around the same time. Ideally these fossils are used to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swamp
A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in creating this environment. Swamps vary in size and are located all around the world. The water of a swamp may be fresh water, brackish water, or seawater. Freshwater swamps form along large rivers or lakes where they are critically dependent upon rainwater and seasonal flooding to maintain natural water level fluctuations.Hughes, F.M.R. (ed.). 2003. The Flooded Forest: Guidance for policy makers and river managers in Europe on the restoration of floodplain forests. FLOBAR2, Department of Geography, University of Cambridge, Cambridge, UK. 96 p. Saltwater swamps are found along tropical and subtropical coastlines. Some swamps have hammock (ecology), hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overbank
An overbank is an alluvial geological deposit consisting of sediment that has been deposited on the floodplain of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in suspension, and because it is carried outside of the main channel, away from faster flow, the sediment is typically fine-grained. An overbank deposit usually consists primarily of fine sand, silt and clay. Overbank deposits can be beneficial because they refresh valley soils. Overbank deposits can also be referred to as floodplain deposits. Examples include natural levees and crevasse splays. Geomorphology Floodplains are far wider than the channel they border, reaching widths of up to 100 kilometers, and their length is 10 times that. They are thin and roughly planar in shape. Unlike channel bars, which often build horizontally, overbank deposits build vertically. Depositional processes and facies Overbank deposits are fine-grained and accumulate verti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
