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Canadian Epoch
The Canadian is the Lower or Early Ordovician in North America. The term is common in the older literature and has been well understood for more than a century. However it has no official recognition by the International Commission on Stratigraphy (ICS) and has been superseded by the more recently defined Ibexian series of western Utah. Background Dana introduced the Canadian as the name for a system separated from the rest of the Ordovician (Weller 1980), then known as the Lower Silurian, and referred to the rest of the Lower Silurian as the Trenton System. At that time the Ordovician had not yet been recognized. Later Ulrich redefined the Canadian as roughly equivalent to the Beekmantown strata of the Lower Ordovician. Flower (1957 p. 17) felt that recognition of the Canadian as a separate system would greatly solve problems in Early Paleozoic stratigraphy. As such, faunas in limestones of Canadian age are uniformly widespread and set off sharply from black shale graptolite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozarks
The Ozarks, also known as the Ozark Mountains, Ozark Highlands or Ozark Plateau, is a physiographic region in the U.S. states of Missouri, Arkansas, Oklahoma and the extreme southeastern corner of Kansas. The Ozarks cover a significant portion of northern Arkansas and most of the southern half of Missouri, extending from Interstate 40 in central Arkansas to Interstate 70 in central Missouri. There are two mountain ranges in the Ozarks: the Boston Mountains of Arkansas and the St. Francois Mountains of Missouri. Buffalo Lookout, the highest point in the Ozarks, is located in the Boston Mountains. Geologically, the area is a broad dome with the exposed core in the ancient St. Francois Mountains. The Ozarks cover nearly , making it the most extensive highland region between the Appalachians and Rockies. Together with the Ouachita Mountains, the area is known as the U.S. Interior Highlands. The Salem Plateau, named after Salem, Missouri, makes up the largest geologic area o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion Surface
In geology and geomorphology, an erosion surface is a surface of rock or regolith that was formed by erosion and not by construction (e.g. lava flows, sediment deposition) nor fault displacement. Erosional surfaces within the stratigraphic record are known as unconformities, but not all unconformities are buried erosion surfaces. Erosion surfaces vary in scale and can be formed on a mountain range or a rock. Particularly large and flat erosion surfaces receive the names of peneplain, paleoplain, planation surface or pediplain. An example of erosion surface is road surface erosion which is caused by natural and anthropogenic factors. Erosion surface can be measured through direct, contact measurement methods and indirect, non-contact measurement methods. Road surface erosion Just like mountains and rocks, erosion can also occur on unsealed roads due to natural and anthropogenic factors. Road surface erosion could be caused by snowfall, rainfall and wind. The material and hydr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arenigian
In geology, the Arenig (or Arenigian) is a time interval during the Ordovician period and also the suite of rocks which were deposited during this interval. History The term was first used by Adam Sedgwick in 1847 with reference to the "Arenig Ashes and Porphyries" in the neighbourhood of Arenig Fawr, in Merioneth, North Wales. The rock-succession in the Arenig district has been recognized by W. G. Fearnsides (“On the Geology of Arenig Fawr and Moel Llanfnant", Q.J.G.S. vol. lxi., 1905, pp. 608–640, with maps). The above succession is divisible into: # A lower series of gritty and calcareous sediments, the "Arenig Series" as it is now understood; # A middle series, mainly volcanic, with shale, the "Llandeilo Series"; and # The shale and limestones of the Bala or Caradoc Stage. It was to the middle series (2) that Sedgwick first applied the term "Arenig". In the typical region and in North Wales generally the Arenig series appears to be unconformable upon the Cambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Champlain
, native_name_lang = , image = Champlainmap.svg , caption = Lake Champlain-River Richelieu watershed , image_bathymetry = , caption_bathymetry = , location = New York/Vermont in the United States; and Quebec in Canada , coords = , type = , inflow = Otter Creek, Winooski River, Missisquoi River, Poultney River, Lamoille River, Ausable River, Chazy River, Boquet River, Saranac River, La Chute River , outflow = Richelieu River , catchment = , basin_countries = Canada, United States , length = , width = , area = , depth = , max-depth = , volume = , residence_time = 3.3 years , shore = , elevation = , islands = 80 ( Grand Isle, North Hero, Isle La Motte, '' see list'') , cities = Burlington, Vermont; Plattsburgh, New York Lake Champlain ( ; french: Lac Champlain) is a natural freshwater lake in North America. It mostly lies between the US states of New York and Vermont, but also extends north into the Canadian province of Quebec. The New York portion of the Ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
