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Sill (geology)
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock. A sill is a ''concordant intrusive sheet'', meaning that it does not cut across preexisting rock beds. Stacking of sills builds a sill complex. and a large magma chamber at high magma flux. In contrast, a dike is a discordant intrusive sheet, which does cut across older rocks. Formation Sills are fed by dikes, except in unusual locations where they form in nearly vertical beds attached directly to a magma source. The rocks must be brittle and fracture to create the planes along which the magma intrudes the parent rock bodies, whether this occurs along preexisting planes between sedimentary or volcanic beds or weakened planes related to foliation in metamorphic rock. These planes or weakened areas allow the intrusion of a thin sheet-like body of magma paralleling the existi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Difference Between A Sill And A Dike
''The'' is a grammatical Article (grammar), article in English language, English, denoting nouns that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the Most common words in English, most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with nouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weathering
Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs '' in situ'' (on-site, with little or no movement), and so is distinct from erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity. Weathering processes are either physical or chemical. The former involves the breakdown of rocks and soils through such mechanical effects as heat, water, ice and wind. The latter covers reactions to water, atmospheric gases and biologically produced chemicals with rocks and soils. Water is the principal agent behind both kinds, though atmospheric oxygen and carbon dioxide and the activities of biological organisms are also important. Biological chemical weathering is also called biological weathering. The materials left after the rock breaks down combine with organic material to create so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skaergaard Intrusion
The Skaergaard intrusion is a layered igneous intrusion in the Kangerlussuaq area of East Greenland and is composed of various rocks and minerals including gabbro, olivine, apatite, and basalt. History and background The Skaergaard intrusion was formed 56 million years ago during the opening of the North Atlantic Ocean. The intrusion was emplaced beneath the preexisting rock in the region, including plateau basalt and gneiss. The intrusion has a general oval shape, which is atypical in igneous emplacement. Due to the tectonic activity in East Greenland, the intrusion is now slightly tilted towards the sea. Specifically, the lower parts of the intrusion are exposed to the north while sections of the roof are conserved to the south. Discovery and early studies The Skaergaard intrusion was first discovered by Lawrence Wager on his Arctic Air-Route Expedition in 1930. In 1933, the first aerial photography of the region was taken in order to create a topographic map of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjacent Islands of Scotland, islands, principally in the archipelagos of the Hebrides and the Northern Isles. To the south-east, Scotland has its Anglo-Scottish border, only land border, which is long and shared with England; the country is surrounded by the Atlantic Ocean to the north and west, the North Sea to the north-east and east, and the Irish Sea to the south. The population in 2022 was 5,439,842. Edinburgh is the capital and Glasgow is the most populous of the cities of Scotland. The Kingdom of Scotland emerged as an independent sovereign state in the 9th century. In 1603, James VI succeeded to the thrones of Kingdom of England, England and Kingdom of Ireland, Ireland, forming a personal union of the Union of the Crowns, three kingdo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peridotite
Peridotite ( ) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle. The compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole. Peridotite is the dominant rock of the upper part of Earth's mantle. The compositions of peridotite nodules found in certain basalts are of special interest along with diamond pipes ( kimberlite), because they provide samples of Earth's mantle brought up from depths ranging from about 30 km to 200 km or more. Some of the nodules preserve isotope ratio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rùm
Rùm (), a Scottish Gaelic language, Scottish Gaelic name often Anglicisation, anglicised to Rum ( ), is one of the Small Isles of the Inner Hebrides, off the west coast of Scotland, in the district of Lochaber. For much of the 20th century the name became Rhum, a spelling invented by the former owner, George Bullough, 1st Baronet Bullough, Sir George Bullough, because he did not relish the idea of having the title "Laird of Rum". It is the largest of the Small Isles, and the 15th largest Scottish island, and is inhabited by 40 people, all of whom live in the hamlet of Kinloch, Rùm, Kinloch on the east coast. The island has been inhabited since the 8th millennium BC and provides some of the earliest known evidence of human occupation in Scotland. The early Celts, Celtic and Norsemen, Norse settlers left only a few written accounts and artefacts. From the 12th to 13th centuries on, the island was held by various clans including the Clan MacLean, MacLeans of Coll. The population ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phanerozoic
The Phanerozoic is the current and the latest of the four eon (geology), geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present. It is the eon during which abundant animal and plant life has population growth, proliferated, evolutionary radiation, diversified and colonization (biology), colonized various ecological niche, niches on the Earth's surface, beginning with the Cambrian period when animals first developed hard shells that can be clearly preserved in the fossil record. The time before the Phanerozoic, collectively called the ''Precambrian'', is now divided into the Hadean, Archean, Archaean and Proterozoic eons. The time span of the Phanerozoic starts with the Cambrian Explosion, sudden appearance of fossilised evidence of a number of animal phylum (biology), phyla; the evolution of those phyla into diverse forms; the evolutionary history of plants, evolution of plants; the evolution of fish, arthropods ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stillwater Igneous Complex
The Stillwater igneous complex is a large layered mafic intrusion (LMI) located in southern Montana in Stillwater, Sweet Grass and Park Counties. The complex is exposed across 30 miles (48 km) of the north flank of the Beartooth Mountain Range. The complex has extensive reserves of chromium ore and has a history of being mined for chromium. More recent mining activity has produced palladium and other platinum group elements.The Stillwater Complex: A review of the geology by I. S. McCallum http://serc.carleton.edu/files/NAGTWorkshops/petrology03/McCallum.Stillwater.doc Geology The Stillwater complex is a large layered intrusion with many similarities to the Bushveld igneous complex of South Africa. The complex was intruded into existing gneisses during the Archean at about 2700 Ma. Host rocks on the northern side are Archean sedimentary rocks while the southern boundary includes Precambrian rocks of granite, granite gneiss and schist. The Precambrian rock on its sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Superior
Lake Superior is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. Lake Michigan–Huron has a larger combined surface area than Superior, but is normally considered two separate lakes. and the third-largest freshwater lake by volume, holding 10% of the fresh water in all of the world's rivers and lakes. Located in central North America, it is the northernmost and westernmost of the Great Lakes of North America, straddling the Canada–United States border with the Canadian province of Ontario to the north and east and the U.S. states of Minnesota to the west and Michigan and Wisconsin to the south. It drains into Lake Huron via St. Marys River, then through the lower Great Lakes to the St. Lawrence River and ultimately the Atlantic Ocean. Name The Ojibwe name for the lake is ''gichi-gami'' (in syllabics: , pronounced ''gitchi-gami'' or ''kitchi-gami'' in different dialects), meaning "great sea". ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Duluth Complex
The Duluth Complex, the related Beaver Bay Complex, and the associated North Shore Volcanic Group are rock formations which comprise much of the basement bedrock of the northeastern part of the U.S. state of Minnesota in central North America. The Duluth and Beaver Bay complexes are intrusive rocks formed about 1.1 billion years ago during the Midcontinent Rift; these adjoin and are interspersed with the extrusive rocks of the North Shore Volcanic Group produced during that same geologic event. These formations are part of the Superior Upland physiographic region of the United States, which is associated with the Laurentian Upland of the Canadian Shield, the core of the North American Craton. Location The Duluth Complex includes much of Minnesota's Arrowhead Region north of Lake Superior. From the west near Duluth, Minnesota, it arcs north and northeast to about 48° north latitude south of Knife Lake, proceeds east at that latitude some five to twenty kilometers distant from a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Dyke
The Great Dyke or Dike is a linear geological feature that trends nearly north-south through the centre of Zimbabwe passing just to the west of the capital, Harare. It consists of a band of short, narrow ridges and hills spanning for approximately . The hills become taller as the range goes north, and reach up to above the Mvurwi Range. The range is host to vast ore deposits, including gold, silver, chromium, platinum, nickel and asbestos. Geology and soils Geologically the Great Dyke is not a dyke, but is lopolithic and Y-shaped in cross-section. It is a group of layered ultramafic intrusions that extend across Zimbabwe with a strike of about N20°E. The width of the intrusions vary from 3 to . The Great Dyke is unusual in that most ultramafic layered intrusions display near horizontal sill or sheet forms. The well-layered lower units of ultramafic rocks comprising the Great Dyke are locally overlain by erosional remnants of gabbroic rock. These mark the centres of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insizwa (geology)
''Insizwa'' is a genus of tephritid or fruit flies in the family Tephritidae The Tephritidae are one of two fly families referred to as fruit flies, the other family being the Drosophilidae. The family Tephritidae does not include the biological model organisms of the genus '' Drosophila'' (in the family Drosophilidae .... Species *'' Insizwa oblita'' (Munro, 1929) References Tephritinae Tephritidae genera Diptera of Africa {{Tephritinae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
