| 单词 | metamorphic |
| 例句 | “Granite and slate,” he said each time we visited, “maybe a little soapstone, sprinkled with limestone and quartz. Minerals galore! It’s a smorgasbord of metamorphic marvels!” Each Little Bird That Sings 2005-03-01T00:00:00Z I waited for him in silence each time, studying the metamorphic marvel we were walking on. Each Little Bird That Sings 2005-03-01T00:00:00Z Slate is a metamorphic rock consisting of numerous minerals. Restoring the color to slate that’s lost its blackness 2019-09-13T04:00:00Z Who knew that the Georgetown Intrusive Suite was a “group of rocks formed by the intrusion of magma into metamorphic” rocks? ‘Field Guide to the Natural World of Washington, D.C.’ displays a city’s wildlife The rock is metamorphic, in that volcanic heat and pressure has altered its structure somewhat. Scotland's rocky road: a journey to the edge of Lewis – a photo essay 2017-06-28T04:00:00Z Watching the cast move seamlessly from raffiné propriety to violent anarchy is a rousing testament to the metamorphic joys of acting. Review: ‘Ubu Roi,’ Mom and Dad’s Party of Grown-Up Grotesques 2015-07-23T04:00:00Z Then: heat from the interior, metamorphic rock, clouds of steam hiding the sun; clouds, torrential rains, ocean basins filling, rivers, mountains, streams, sand, gravel, clay, sedimentary rock. “Life Story,” Virginia Lee Burton’s Picture Book for the Ages 2015-10-08T04:00:00Z If this was a show about water’s metamorphic power, and of women as bearers of water and life, I would have preferred a more sustained engagement with those themes. A Splashy, Messy All-Naked Revue 2022-10-06T04:00:00Z More than mere oases, works of botanical urban art call attention to the metamorphic nature of cities themselves, the way the urban cycle of construction, decay, restoration and demolition mimics that of nature. | Graffiti Made of Plants, Not Paint 2014-05-02T17:36:09Z The Waverly Street Gallery show emphasizes earth and mineral tones, striated as if pulled directly from slices of metamorphic stone. At the Corner Store, Goertel’s photos make a splash without the flash 2015-03-26T04:00:00Z A similar, if not always as potent, metamorphic magic imbues “The Lyons,” Mr. Silver’s best play since “The Food Chain” 16 years ago. | 'The Lyons': ?The Lyons,? by Nicky Silver, at Vineyard Theater - Review 2011-10-12T02:05:01Z Igneous, metamorphic, marine sedimentary rocks — in all shapes, sizes and textures, plus a multitude of colors. Four destinations that feel like geologic theme parks 2021-10-14T04:00:00Z Thus, after the Capitol was burned during the War of 1812, reconstruction made use of marble — a harder, metamorphic rock found on the upper Potomac. Hiking along Virginia’s Aquia Creek and finding history a stone’s throw from home 2021-04-01T04:00:00Z Adventitious rhyming, such as this supple verse form allows, is the natural ally of Lewis's remarkably resourceful wit and her gift for metamorphic imagination. A Hospital Odyssey by Gwyneth Lewis 2010-04-16T23:10:00Z “Even when he was ill, he had that great stillness and great dignity,” said Wilson, who credited Rickman’s professional success to his ability to be “very metamorphic, he could take on anything”. 'We are all so devastated': tributes pour in to Alan Rickman from acting world 2016-01-14T05:00:00Z A metamorphic time, when nature quietly gathers within itself. In a world moving at breakneck speed, growing indoor plants is teaching me patience | Mel Campbell 2019-06-18T04:00:00Z As Netflix endures another week of the maelstrom created by Dave Chappelle’s controversial comedy special that shows no signs of slowing down, the streamer finds itself on the edge of a metamorphic moment. How the controversy over Dave Chappelle’s special put Netflix on blast 2021-10-20T04:00:00Z Thomas pulls back a metamorphic curtain on the Wednesday amateur nights, which began in the 1930s and continue today. Apollo Theater Is Celebrated in a New Graphic Novel 2019-01-02T05:00:00Z The way things turned out, she was captured and through some hideous scientific means her metamorphic properties were decanted to create the Sentinels. X-Men: Days of Future Past review – chaotic but fun 2014-05-22T04:00:00Z One of Picasso's 1920s styles, I should say, for this metamorphic creator was constantly generating profoundly new ideas. Picasso and Modern British Art ? review 2012-02-13T16:01:52Z But the winner was a team of UW graduate students from the Earth and Space Sciences Department with the name "We're Kinda the Schist," named after metamorphic rock. Burke Museum seeks trivia geeks 2011-04-06T20:52:03Z While Schindler takes a philosophical view of physical change, other participants highlight the metamorphic quality of their artistic methods. Review | In the galleries: Building on an artwork expressed via different media 2021-04-22T04:00:00Z It’s a metamorphic rock called schist, compressed by mountains thought to have once been as tall as the Himalayas. Four destinations that feel like geologic theme parks 2021-10-14T04:00:00Z Ms. Lloyd’s “Henry” is, among other things, a celebration of the metamorphic wonder of live stage acting, and of the distinctive insights it affords as we watch people transform themselves into others. Review: ‘Henry IV,’ Donmar Warehouse’s All-Female Version 2015-11-11T05:00:00Z This show of 17 large works from the last 20 years demonstrates her metamorphic methods as baroque elaborations mutate into geisha cartoons. This week's new exhibitions 2012-05-18T23:05:00Z It’s a metamorphic rock, which means it becomes something new under extreme heat and pressure without melting. Earth is a geological oddball in our solar system. This is why. 2023-10-12T04:00:00Z A lot of bodies that are depicted but not in a traditional way, but rather distorted, expanded in a metamorphic phase. Why this Venice Biennale curator didn't need quotas to show more women artists than ever 2022-10-10T04:00:00Z Describe the differences among primitive, igneous, sedimentary, and metamorphic rock, and relate these differences to their origins. Astronomy 2016-10-13T00:00:00Z The person with knowledge of the matter said that the group’s name derived from the metamorphic rock, signaling the group’s intent to be enduring and maintain a clarity of purpose. An Unusual $1.6 Billion Donation Bolsters Conservatives 2022-08-22T04:00:00Z Equipment designed for the softer, cooler sedimentary rock often found in oil fields falters in the extremes of hot, hard metamorphic rocks such as granite. In Utah, researchers are trying to unlock Earth’s heat and make geothermal energy a reality 2022-07-13T04:00:00Z But on other worlds, it’s more typical to find metamorphic rocks forged in the split-second shock of a meteoroid impact. Earth is a geological oddball in our solar system. This is why. 2023-10-12T04:00:00Z The rock failed along weakened foliation planes of the metamorphic rock on Johnson Peak, in an area that had been eroded into a steep slope by glacial ice. Physical Geology 2015-01-01T00:00:00Z Terrestrial rocks can be classified as igneous, sedimentary, or metamorphic. Astronomy 2016-10-13T00:00:00Z Solid sedimentary, igneous, or metamorphic bedrock shakes less than unconsolidated sediments. An Introduction to Geology 2017-01-01T00:00:00Z Marble, the metamorphic rock, embodied for me a dark paradox: It is change that produces changelessness. When I Went Away From the World 2022-04-19T04:00:00Z He wraps a hard hand around her thigh, and at that point of contact Bernini has made metamorphic rock soft, impossibly. Contemplating Beauty in a Disabled Body 2022-03-29T04:00:00Z Igneous or metamorphic rocks have the lowest primary porosity because they commonly form at depth and have interlocking crystals. Physical Geology 2015-01-01T00:00:00Z The streaming company now finds itself on the edge of a metamorphic moment. Dave Chappelle’s controversial comedy special is a catalyst for change as Netflix walkout leads to calls for reform 2021-10-20T04:00:00Z Anthracite is the highest metamorphic grade and most desirable coal since it provides the highest energy output. An Introduction to Geology 2017-01-01T00:00:00Z Most of the outcrops, and especially riprap, around here is fairly local, and is mostly granitic or metamorphic, with its origins not too far away in the Cascades. What We Can Learn from These Marvelous Out-of-Context Rocks 2019-06-30T04:00:00Z Schist, a hard metamorphic rock, lies closer to the Earth’s surface in those two places and supports the skyscrapers’ great tonnage. Review | For the human race, geology is destiny 2019-05-31T04:00:00Z The main factors that control metamorphic processes are: Physical Geology 2015-01-01T00:00:00Z The dark, blocky cylinder appears to comprise a roughly fifty–fifty mix of ice and a metamorphic rock called gneiss, Talalay says. Chinese crew extract first rock from beneath East Antarctic ice in 60 years 2019-03-04T05:00:00Z Foliated textures come from platy minerals forming planes in a rock, while non-foliated metamorphic rocks have no internal fabric. An Introduction to Geology 2017-01-01T00:00:00Z It's not uncommon to find round, deep red garnet crystals embedded like pomegranate seeds in metamorphic rocks. The Astonishing Origin of Garnets in Rhyolite 2019-02-03T05:00:00Z The rock is about as old as the oldest rocks found on Earth—metamorphic rocks from Canada and Greenland. Ancient Earth rock found on the moon 2019-01-29T05:00:00Z In most cases, this is sedimentary or igneous rock, but metamorphic rock that reaches the surface and is then reburied can also be considered a parent rock. Physical Geology 2015-01-01T00:00:00Z As more people come here, seeking opportunity, the city will continue its metamorphic change, gaining some things while losing others. Boomtown Seattle: Why we move here — and how we’re all in it together 2018-02-22T05:00:00Z Thumbnail: Folded foliation in a metamorphic rock from near Geirangerfjord, Norway. An Introduction to Geology 2017-01-01T00:00:00Z Actually, the metamorphic ability of this interesting critter reminds me strongly of Trump's shape-shifting and survival past bankruptcies. The Smiling Axolotl Hides a Secret: A Giant Genome 2018-02-01T05:00:00Z One idea is that when igneous or metamorphic rocks are under stress, their molecular bonds break and release ionized oxygen that travels through the rock. What caused the mysterious lights in the night sky after Mexico’s earthquake? 2017-09-15T04:00:00Z Pressure is important in metamorphic processes for two main reasons. Physical Geology 2015-01-01T00:00:00Z Then the three main rock types are presented: igneous, sedimentary, and metamorphic. Rocks: A Handy Book for Tiny Geologists 2017-07-29T04:00:00Z Most metamorphic processes take place deep underground, inside the earth’s crust. An Introduction to Geology 2017-01-01T00:00:00Z You may recall from your high school geology class that natural stone falls into one of three basic geological classifications: metamorphic, sedimentary and igneous. Seven tips for cleaning natural stone | Provided By Seal Team One 2017-05-15T04:00:00Z Westall said it remains possible that the haematite structures were formed as a result of the high temperatures and pressures experienced by metamorphic rocks. World's oldest fossils found in Canada, say scientists 2017-03-01T05:00:00Z So not only does water facilitate metamorphic reactions on a grain-to-grain basis, it also allows for the transportation of ions from one place to another. Physical Geology 2015-01-01T00:00:00Z Beneath it was mostly schist, metamorphic rock that Mount described as weathered and fractured. Government severely misjudged strength of Oroville emergency spillway, sparking a crisis 2017-02-19T05:00:00Z Higher temperatures would create magma, and thus, would no longer be a metamorphic process. An Introduction to Geology 2017-01-01T00:00:00Z One example might be warm, wet plains, on metamorphic rock, with mostly deciduous forest. 3D ocean map tracks ecosystems in unprecedented detail 2017-01-02T05:00:00Z Seeing the world from above is a metamorphic experience. How Drones Are Changing Our View of the World 2016-11-18T05:00:00Z For this reason, it is very difficult to study metamorphic processes in a lab. Physical Geology 2015-01-01T00:00:00Z What I mean is the combination of all these things into a period of metamorphic transition here at the end of a legendary life. The Mysterious Metamorphosis of Chuck Close 2016-07-13T04:00:00Z In a manner like the Gros Ventre slide, foliation planes of weakness in metamorphic rock outcrops were parallel with the surface, compromising shear strength. An Introduction to Geology 2017-01-01T00:00:00Z On Earth, tridymite generally forms at high temperatures in volcanic or metamorphic rocks, not a finely layered sedimentary rock like Buckskin. Mars Rover Finds Changing Rocks, Surprising Scientists 2015-12-17T05:00:00Z THE great, metamorphic trick for public figures ensnared in scandals is somehow to portray themselves as victims of their own transgressions. Sins of the fathers 2015-11-12T05:00:00Z For example, one important metamorphic setting is many kilometres deep within the roots of mountain ranges. Physical Geology 2015-01-01T00:00:00Z Stuttering beats and restless, metamorphic song structures complement the singer's sense of disorientation and disquiet as he approaches 40, Mercury Prize 2015: The nominees - BBC News 2015-10-16T04:00:00Z The metamorphic rock, amphibolite, is primarily composed of amphibole minerals. An Introduction to Geology 2017-01-01T00:00:00Z Rises of metamorphic rock and shale pounded smooth by Indian moccasins long ago, glisten, undulate as the back of a whale, while the Bronx River thunders, cascades or eases silken over silt. Forest Walk at the Botanical Garden 2015-09-09T04:00:00Z Slate is a metamorphic stone, Brad explained, compacted over millennia. ‘It’s Buckingham,’ he said. ‘It’s expensive, but it lasts forever.’ The story of the slate on my roof. 2015-02-01T05:00:00Z Temperature contours are shown, and the metamorphic zones are depicted using colours similar to those in Figure 7.22. Physical Geology 2015-01-01T00:00:00Z It is an iconic mass of granite geologically formed by fire, but it certainly also qualifies as a sedimentary and metamorphic chunk of American political culture. America’s First Rock Star 2014-11-25T05:00:00Z Mica minerals are usually found in igneous and metamorphic rocks, while clay minerals are more often found in sedimentary rocks. An Introduction to Geology 2017-01-01T00:00:00Z The Manhattan Schist Formation is the best known of the local metamorphic rock formations, and is visible in the outcroppings in Central Park. Decade of Tunnel Excavations Brings Geologists Blessings From Below 2014-02-18T01:35:17Z Also in Ethiopia gold is associated with the proterozoic metamorphic rocks, found to the west of the Afar lowlands, where recent volcanic rocks mark the Great Rift System of the African plate. In Search of the Lost Land of Gold (and mummified baboons too) 2013-08-30T21:45:04.883Z As they lost mass the base of the crust gradually rebounded, pushing up the core of the metamorphosed region so that the once deeply buried metamorphic zones are now exposed at surface. Physical Geology 2015-01-01T00:00:00Z When the bit of metamorphic rock that would become Florida’s basement rifted off of proto-Africa in the time of Pangea, a basin formed as the baby Atlantic Ocean was born. Living (and Sometimes Dying) with Karst 2013-03-07T14:15:07.193Z Other sheet silicates include serpentine and chlorite, found in metamorphic rocks. An Introduction to Geology 2017-01-01T00:00:00Z You’ll find sapphires in some volcanic fields, and in metamorphic rocks like gneiss, mica schist and sometimes marble. The Real Heart of the Ocean 2012-04-14T14:45:05.383Z The second is the zone of the snowy peaks and of the lower Himalaya, and is composed chiefly of crystalline and metamorphic rocks together with unfossiliferous sedimentary beds supposed to be of Palaeozoic age. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 4 "Hero" to "Hindu Chronology" 2012-04-04T02:00:56.447Z Foliation is a key feature of metamorphic rocks formed under directed pressure; foliated metamorphic rocks include slate, phyllite, schist, and gneiss. Physical Geology 2015-01-01T00:00:00Z This is a region of ancient and metamorphic Paleozoic rocks on the eastern side, and mainly Triassic rocks on the west. Encyclopaedia Britannica, 11th Edition, Volume 13, Slice 8 "Hudson River" to "Hurstmonceaux" 2012-02-24T03:00:27.173Z While not strictly a metamorphic structure, they are common around shock metamorphism. An Introduction to Geology 2017-01-01T00:00:00Z DALRADIAN, in geology, a series of metamorphic rocks, typically developed in the high ground which lies E. and S. of the Great Glen of Scotland. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 9 "Dagupan" to "David" 2012-02-11T03:03:39.807Z He explained that the outcrop was made of metamorphic rock that was formed 15 to 20 miles beneath the earth’s surface. City Room: Colliding Continents Created the Rock Formation in a Children's Playground 2012-02-05T19:30:17Z How do variations in the geothermal gradient affect the depth at which different metamorphic rocks form? Physical Geology 2015-01-01T00:00:00Z It is essentially metamorphic and occurs with gneisses, schists and granulites, especially in the Scandinavian peninsula, where it is regarded as being very characteristic of certain horizons. Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7 "Gyantse" to "Hallel" 2011-12-26T03:00:11.613Z Aluminum concentrates in soils as feldspar and ferromagnesian minerals in igneous and metamorphic rocks undergo chemical weathering processes. An Introduction to Geology 2017-01-01T00:00:00Z These rocks, on account of their equivocal position, are called metamorphic. Harper's New Monthly Magazine Vol. IV, No. 19, Dec 1851 2011-12-25T03:00:11.297Z This metamorphic bedrock glitters with quartz, feldspar and wine red garnet. City Room: Manhattan Forest, Now Barren, Is Far From Lifeless 2011-12-23T21:20:26Z Rearrange the following minerals in order of increasing metamorphic grade: biotite, garnet, sillimanite, chlorite. Physical Geology 2015-01-01T00:00:00Z While quartzite is a metamorphic sandstone, it is not to be understood that sandstone cannot be metamorphosed in other ways. The Geography of the Region about Devils Lake and the Dalles of the Wisconsin 2011-11-29T03:00:17.347Z In metamorphic rocks, facies are groups of minerals called mineral assemblages. An Introduction to Geology 2017-01-01T00:00:00Z Rather than matching the ages of the zircons, the researchers note, the ages of the inclusions matched the ages of the metamorphic minerals surrounding the zircons. Earth's 'Time Capsules' May Be Flawed 2011-11-17T19:07:05Z In the absence of any data to the contrary, we favor a rapid release that allows the majority of each perturbation to be volcanogenic but that does not preclude a metamorphic carbon source. [Technical Response] Response to Comment on ?Atmospheric Pco2 Perturbations Associated with the Central Atlantic Magmatic Province? 2011-11-03T18:55:20.840Z Two things that a geologist first considers when looking at a metamorphic rock are what the parent rock might have been, and what type of metamorphism has taken place. Physical Geology 2015-01-01T00:00:00Z In general, the metamorphic changes effected by dynamic action are much more profound than those brought about in other ways, and most rocks which have been profoundly metamorphosed, were changed in this way. The Geography of the Region about Devils Lake and the Dalles of the Wisconsin 2011-11-29T03:00:17.347Z This is useful when interpreting the history of metamorphic rock. An Introduction to Geology 2017-01-01T00:00:00Z The central plateau consists almost entirely of metamorphic rocks with extensive tracts of granite in Unyamwezi. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 7 "Geoponici" to "Germany" 2011-09-26T02:00:25.313Z To this series the term “metamorphic” has been applied. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" 2011-09-19T02:00:10.473Z The processes related to metamorphic rocks are at the bottom of the cycle. Physical Geology 2015-01-01T00:00:00Z The Potsdam or any other sandstone formation might be converted into quartzite by the same process, and it would then be a metamorphic rock. The Geography of the Region about Devils Lake and the Dalles of the Wisconsin 2011-11-29T03:00:17.347Z In the late 1800s, British geologist George Barrow mapped zones of index minerals in different metamorphic zones of an area that underwent regional metamorphism. An Introduction to Geology 2017-01-01T00:00:00Z Garnets are very widely distributed, occurring in crystalline schists, gneiss, granite, metamorphic limestone, serpentine, and occasionally in volcanic rocks. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4 "G" to "Gaskell, Elizabeth" 2011-08-24T02:00:20.690Z It is particularly displayed around masses of granite, where sandstones are found altered into quartzite, shales and grits into schistose compounds, and where sometimes fossils are still recognizable among the metamorphic minerals. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 6 "Geodesy" to "Geometry" 2011-09-19T02:00:10.473Z Second, it has implications for the texture of metamorphic rocks. Physical Geology 2015-01-01T00:00:00Z Mr. Distenfeld, 48, is a sculptor who prefers granite gneiss -– the banded metamorphic rock found beneath swaths of New York City -– and in the Nostrand pit he saw a boulder of it. City Room: With Big, Heavy Rocks, a Man Turns a Nuissance Into a Niche 2011-08-14T21:58:35Z Recognizing these facies is the most direct way to interpret the metamorphic history of rock. An Introduction to Geology 2017-01-01T00:00:00Z After lunch they conjugate “aburrir” or memorize the differences between igneous, sedimentary and metamorphic rock. To students, it?s all about the (boring) content 2011-08-14T15:47:26Z To discern at once the steadfast truth and its metamorphic developments will be the task of the greatest wisdom. Modern Society 2011-06-23T02:00:27.897Z First, water facilitates the transfer of ions between minerals and within minerals, and therefore increases the rates at which metamorphic reactions take place. Physical Geology 2015-01-01T00:00:00Z The rocks of Labrador are largely metamorphic, but include ancient igneous intrusions, and are hard and resistant. North America 2011-05-05T02:00:20.027Z This combination of high temperature and low pressure produces numerous metamorphic facies. An Introduction to Geology 2017-01-01T00:00:00Z The collision heated the rock in the boundary to about 400 degrees Celsius, setting off metamorphic reactions that released fluids from the rock, explains Jeremy Richards, a University of Alberta geologist. Royal Gold in Wales: How It Got There and Got Out 2011-04-29T23:15:00.693Z His observations on the geology of South America were given in a masterly essay, and these and subsequent researches threw much light on igneous and metamorphic phenomena and on the resulting changes in rock-formations. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 6 "Foraminifera" to "Fox, Edward" 2011-04-22T02:00:08.637Z Most metamorphic reactions take place at very slow rates. Physical Geology 2015-01-01T00:00:00Z In the Rhode Island field the rocks associated with the coal are plainly metamorphic in character, and the coal has, in large part, been changed to graphitic anthracite. North America 2011-05-05T02:00:20.027Z As with all metamorphic rock, the parent rock texture and chemistry are major factors in determining the final outcome of the metamorphic process, including what index minerals are present. An Introduction to Geology 2017-01-01T00:00:00Z This county includes in the north an area of the gneiss that is discussed under county Donegal, and, west of Omagh, a metamorphic region that stretches in from the central axis of Tyrone. Encyclopaedia Britannica, 11th Edition, Volume 10, Slice 3 "Fenton, Edward" to "Finistere" 2011-03-14T03:01:00.580Z He has a metamorphic shape,-5- that of the Spider. Jamaican Song and Story Annancy stories, digging sings, ring tunes, and dancing tunes 2011-02-28T03:00:31.280Z While the rate of metamorphism is slow, the tectonic processes that lead to metamorphism are also very slow, so in most cases, the chance for metamorphic reactions to be completed is high. Physical Geology 2015-01-01T00:00:00Z The richest iron ores of North America are of this nature, and will be referred to below in connection with other substances of economic importance contained in the metamorphic rocks. North America 2011-05-05T02:00:20.027Z Two frequently found micas are dark-colored biotite, frequently found in granite, and light-colored muscovite, found in the metamorphic rock called schist. An Introduction to Geology 2017-01-01T00:00:00Z The two most important are heat and water; and it is doubtful whether there is a single particle of the globe which has not experienced the metamorphic action of the one or the other. The Religion of Geology and Its Connected Sciences 2011-02-28T03:00:28.890Z There are a number of other metamorphic rocks, but those mentioned are the most commonly occurring species. Geology 2011-02-20T03:00:12.660Z In order to use the K-Ar dating technique, we need to have an igneous or metamorphic rock that includes a potassium-bearing mineral. Physical Geology 2015-01-01T00:00:00Z Segregated and fissure veins occur in either igneous, sedimentary, or metamorphic terranes, but are more commonly of economic importance in the metamorphic rocks than elsewhere, and will be referred to again in that connection. North America 2011-05-05T02:00:20.027Z They are usually found in igneous rocks, such as granite, rhyolite, and basalt as well as metamorphic rocks and detrital sedimentary rocks. An Introduction to Geology 2017-01-01T00:00:00Z These rocks are metamorphic, and though having a mineral constitution somewhat similar to that of diorite, they have been produced really from rocks of more basic character, such as diabase, dolerite and gabbro. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 6 "English Language" to "Epsom Salts" 2011-02-19T03:00:59.807Z How may granite be at one and the same time a metamorphic and igneous rock? Geology 2011-02-20T03:00:12.660Z When radiometric techniques are applied to metamorphic rocks, the results normally tell us the date of metamorphism, not the date when the parent rock formed. Physical Geology 2015-01-01T00:00:00Z A very large proportion of both the quartz and placer mining of North America is in regions occupied by metamorphic rock. North America 2011-05-05T02:00:20.027Z The primary way metamorphic rocks are identified is with texture. An Introduction to Geology 2017-01-01T00:00:00Z Here are strata deposited by the miocene tertiary; here are breakings forth of metamorphic rocks of many periods; here are the complex results of diverse influences and forces. The Westerners 2011-02-14T03:00:39.347Z What is the general character of metamorphic rocks? Geology 2011-02-20T03:00:12.660Z Of the consolidated rocks, well-fractured volcanic rocks and limestone that has cavernous openings produced by dissolution have the highest potential porosity, while intrusive igneous and metamorphic rocks, which formed under great pressure, have the lowest. Physical Geology 2015-01-01T00:00:00Z With the disintegration of the metamorphic terranes the gold is set free, and may be still further concentrated by streams so as to form the well-known placers. North America 2011-05-05T02:00:20.027Z Grade describes the amount of metamorphism in a rock, and facies are a set of minerals that can help guide an observer to an interpretation of the metamorphic history of a rock. An Introduction to Geology 2017-01-01T00:00:00Z The form of his ideals was modified by the metamorphic glow of Transcendentalism which passed through the region of Boston in the second quarter of the 19th century. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z What are metamorphic rocks, and what is their general appearance? Geology 2011-02-20T03:00:12.660Z Fractured igneous and metamorphic rocks, and especially fractured volcanic rocks, can be highly permeable, as can limestone that has been dissolved along fractures and bedding planes to create solutional openings. Physical Geology 2015-01-01T00:00:00Z It is in metamorphic rocks that the geologist looks for gems, the precious metals, crystalline marble, magnetic iron, etc. North America 2011-05-05T02:00:20.027Z The rock cycle shows that both igneous and sedimentary rocks can become metamorphic rocks. An Introduction to Geology 2017-01-01T00:00:00Z It is aptly named, with kilometer-scale folds of Precambrian metamorphic rocks. Scientist at Work: Answering Questions About Antarctica 2011-01-22T16:00:18Z What are some of the appearances relied upon for distinguishing metamorphic from igneous granite? Geology 2011-02-20T03:00:12.660Z An aquitard is a body that does not allow transmission of a significant amount of water, such as a clay, a till, or a poorly fractured igneous or metamorphic rock. Physical Geology 2015-01-01T00:00:00Z Certain ores and rocks contained in metamorphic terranes owe their concentration to previously acting processes of concentration, but have undergone chemical changes in place. North America 2011-05-05T02:00:20.027Z The pressure that affects metamorphic rocks can be grouped into confining pressure and directed stress. An Introduction to Geology 2017-01-01T00:00:00Z Happily, we collected a variety of igneous and metamorphic rocks that will help fill in the hole left by several other unproductive sites. Scientist at Work: Rocks, Zircon Zapping and a Big Shrimp 2011-01-07T21:02:35Z It is probably both igneous and metamorphic, however. Geology 2011-02-20T03:00:12.660Z In most cases, the movement is parallel to a fracture, bedding, or metamorphic foliation plane, and it can range from very slow to moderately fast. Physical Geology 2015-01-01T00:00:00Z Many of the metamorphic terranes consist essentially of quartz, feldspar, and mica, which have been formed by the rearrangement of the mineral matter contained in the rocks during their previous state. North America 2011-05-05T02:00:20.027Z Strain is the result of this stress, including metamorphic changes within minerals. An Introduction to Geology 2017-01-01T00:00:00Z Near faster ice streams, like Byrd Glacier, we found a rich assortment of igneous and metamorphic rocks, probably eroded from the upstream craton, even though the local nunatak geology exposes only Beacon and Ferrar. Scientist at Work: Rocks, Zircon Zapping and a Big Shrimp 2011-01-07T21:02:35Z Some geologists consider it to be invariably an igneous rock; but, as just stated, it sometimes passes into gneiss in such a way as to lead us to infer its metamorphic origin. Geology 2011-02-20T03:00:12.660Z One is garnet, which is common in some metamorphic rocks and typically displays the dodecahedral shape. Physical Geology 2015-01-01T00:00:00Z So intimate is the association of gold with metamorphic rocks that this is one of the main guides in searching for it, although, as already stated, it is frequently present in other rocks as well. North America 2011-05-05T02:00:20.027Z Strain describes the resultant processes caused by stress and includes metamorphic changes in the minerals. An Introduction to Geology 2017-01-01T00:00:00Z Dylan Taylor examining some of the metamorphic gneisses at Camp Ridge. Scientist at Work: Unraveling the History Beneath the Ice 2010-12-28T21:28:12Z Syenite, like granite, is recognised as an igneous as well as a metamorphic rock. Geology 2011-02-20T03:00:12.660Z What are the processes that lead to the formation of a metamorphic rock? Physical Geology 2015-01-01T00:00:00Z While this scheme of classification is based on the succession of sedimentary beds, igneous and metamorphic rocks have a place in it, providing their age can be determined. North America 2011-05-05T02:00:20.027Z These crystalline changes create identifying textures, which is shown in the figure below comparing the phaneritic texture of igneous granite with the foliated texture of metamorphic gneiss. An Introduction to Geology 2017-01-01T00:00:00Z From moraine sites near the Miller Range, we sampled an abundance of igneous and high-grade metamorphic rocks, not unlike those found locally in the Nimrod Group. Scientist at Work: Unraveling the History Beneath the Ice 2010-12-28T21:28:12Z Thus, highly micaceous sandstones, as they are traced into a metamorphic region, are seen to pass gradually into mica-schist. Geology 2011-02-20T03:00:12.660Z Most metamorphic rocks are formed at depths of kilometres to tens of kilometres. Physical Geology 2015-01-01T00:00:00Z With placer gold, and probably derived largely, if not entirely, from metamorphic rocks, there are frequently found grains of platinum. North America 2011-05-05T02:00:20.027Z This metamorphic process happens at mid-ocean spreading centers where newly formed oceanic crust interacts with seawater. An Introduction to Geology 2017-01-01T00:00:00Z The best one, he said, brought kids to the whiteboard, where they used their fingers to sort words describing metamorphic rocks, as a video played to the side. Some educators question if whiteboards, other high-tech tools raise achievement 2010-06-11T04:00:00Z To avoid repetition it was also necessary, while treating of joints, &c., to give some account of certain structures which are the result of metamorphic action. Geology 2011-02-20T03:00:12.660Z As already noted, the nature of the parent rock controls the types of metamorphic rocks that can form from it under differing metamorphic conditions. Physical Geology 2015-01-01T00:00:00Z More than this, the foliation frequently so characteristic of metamorphic rocks is considered as evidence of a flowing movement or shearing of the material while under pressure. North America 2011-05-05T02:00:20.027Z Slate is a fine-grained metamorphic rock that exhibits a foliation called slaty cleavage that is the flat orientation of the small platy crystals of mica and chlorite forming perpendicular to the direction of stress. An Introduction to Geology 2017-01-01T00:00:00Z Consisting of red sandstones, mudstones and conglomerates, they are inclined at high angles usually away from the granite massif and the encircling metamorphic rocks. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 6 "Armour Plates" to "Arundel, Earls of" But, for sake of clearness, we have reserved special account of the structure and mode of occurrence of metamorphic and igneous rocks to this place. Geology 2011-02-20T03:00:12.660Z The kinds of rocks that can be expected to form at different metamorphic grades from various parent rocks are listed in Table 7.1. Physical Geology 2015-01-01T00:00:00Z In the brief description given of the Archean system on a preceding page, it was stated that the rocks composing it are largely metamorphic. North America 2011-05-05T02:00:20.027Z Non-foliated metamorphic rocks are typically composed of just one mineral and, therefore, usually show the effects of metamorphism with recrystallization in which crystals grow together, but with no preferred direction. An Introduction to Geology 2017-01-01T00:00:00Z The metamorphic rocks are associated with bands of epidiorite which have shared in the folding and metamorphism of the region. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 5 "Arculf" to "Armour, Philip" As a rule, metamorphic strata are contorted, twisted, and crumpled, although here and there comparatively horizontal stretches of altered rocks may be observed. Geology 2011-02-20T03:00:12.660Z Some examples of non-foliated metamorphic rocks are marble, quartzite, and hornfels. Physical Geology 2015-01-01T00:00:00Z Common examples of metamorphic rocks are mica, schist, gneiss, 324 statuary marble, certain granites, etc. North America 2011-05-05T02:00:20.027Z The sequence slate → phyllite → schist → gneiss illustrates an increasing metamorphic grade. An Introduction to Geology 2017-01-01T00:00:00Z The Lower Old Red Sandstone, chiefly composed of volcanic rocks—lavas and tuffs—rests unconformably on the metamorphic series. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 5 "Arculf" to "Armour, Philip" Frequently, it is quite impossible to say what was the original condition of some metamorphic rocks; often, however, this is sufficiently obvious. Geology 2011-02-20T03:00:12.660Z The passage of this water through the oceanic crust at 200° to 300°C promotes metamorphic reactions that change the original pyroxene in the rock to chlorite and serpentine. Physical Geology 2015-01-01T00:00:00Z Such sheets of intruded material cutting across the bedding of stratified rocks, or traversing older igneous or metamorphic terranes, are of common occurrence and are frequently abundant in deeply eroded regions. North America 2011-05-05T02:00:20.027Z Geologists use index minerals that form at certain temperatures and pressures to identify metamorphic grade. An Introduction to Geology 2017-01-01T00:00:00Z Another common mode of occurrence of apatite is in metamorphic crystalline rocks, especially in crystalline limestones: in eastern Canada extensive beds of apatite occur in the limestones associated with the Laurentian gneisses. Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" Granite is recognised as an igneous as well as a metamorphic rock. Geology 2011-02-20T03:00:12.660Z The metamorphic rocks formed from mudrock under regional metamorphosis with a typical geothermal gradient are listed. Physical Geology 2015-01-01T00:00:00Z No satisfactory boundary between these hills of gneiss, schist, and allied metamorphic rocks, and the others of the same general character in the neighbouring portions of New York and New Jersey, has been determined. North America 2011-05-05T02:00:20.027Z These index minerals also provide important clues to a rock’s sedimentary protolith and the metamorphic conditions that created it. An Introduction to Geology 2017-01-01T00:00:00Z The mountain ranges of the east of Brazil, from Cape St Roque to the mouth of the river Plate, are composed chiefly of crystalline and metamorphic rocks. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 4 "Bradford, William" to "Brequigny, Louis" There has been much difference of opinion as to the origin of granite—some holding it to be an igneous rock, others maintaining its metamorphic origin. Geology 2011-02-20T03:00:12.660Z Some common minerals in metamorphic rocks are shown in Figure 7.21, arranged in order of the temperature ranges within which they tend to be stable. Physical Geology 2015-01-01T00:00:00Z In many other cases the metamorphic process itself remains a mystery, and from the nature of the products alone do we conclude that such a metamorphic action has taken place. Geological Report on Asbestos and its Indications, in the Province of Quebec, Canada The names of metamorphic facies on the pressure-temperature diagram reflect minerals and mineral assemblages that are stable at these pressures and temperatures and provide information about the metamorphic processes that have affected the rocks. An Introduction to Geology 2017-01-01T00:00:00Z Some of the metamorphic rocks may belong to the older Palaeozoic period, but the greater part of the series is probably Archaean. Encyclopaedia Britannica, 11th Edition, Volume 4, Slice 4 "Bradford, William" to "Brequigny, Louis" To metamorphose is to change; and metamorphic rocks are those which have been changed by heat or pressure from their original formation. Nature's Miracles, Volume 1 Familiar Talks on Science—World-Building and Life. Earth, Air and Water. When mountains erode, those metamorphic rocks are uplifted by crustal rebound. Physical Geology 2015-01-01T00:00:00Z A rock usually containing much magnesian earth, for the most part unstratified, but sometimes appearing to be an altered or metamorphic stratified rock. Principles of Geology or, The Modern Changes of the Earth and its Inhabitants Considered as Illustrative of Geology Many different styles of metamorphic facies are recognized, tied to different geologic and tectonic processes. An Introduction to Geology 2017-01-01T00:00:00Z Most of the coast of Norway is composed of metamorphic rock; but these islands are of granite, and for marvellous peaks and oddly-pointed shapes, deep, far-reaching gulches and ca�ons, are unequalled elsewhere. Due North or Glimpses of Scandinavia and Russia The metamorphic rocks were primarily igneous and are changed somewhat in their structure by the lapse of time. Nature's Miracles, Volume 1 Familiar Talks on Science—World-Building and Life. Earth, Air and Water. Rocks are made up of mixtures of minerals and can form though igneous, sedimentary, or metamorphic processes. Physical Geology 2015-01-01T00:00:00Z The term, which includes both the plutonic and metamorphic rocks, is substituted for primary, because some members of both these classes, such as granite and gneiss, are posterior to many secondary or fossiliferous rocks. Principles of Geology or, The Modern Changes of the Earth and its Inhabitants Considered as Illustrative of Geology An example of an old regional metamorphic environment is visible in the northern Appalachian Mountains while driving east from New York state through Vermont and into New Hampshire. An Introduction to Geology 2017-01-01T00:00:00Z Geologically, "the country is in the metamorphic higher grounds that rise out of the alluvial flats of Lower Bengal between the Osri and the Barakar rivers." From Sea to Sea Letters of Travel The igneous rocks, then, are the lowest of all; then come the metamorphic rocks; and as before stated, on top of metamorphic rock begins the first evidence of life in its lowest form. Nature's Miracles, Volume 1 Familiar Talks on Science—World-Building and Life. Earth, Air and Water. In Sanskrit, on the contrary, the most essential parts of the two component elements are gone, and what remains is a kind of metamorphic agglomerate which cannot be understood without a most minute microscopic analysis. Lectures on The Science of Language The same strata, therefore, may, according to this view, be very ancient in reference to the time of their deposition, and very modern in regard to the period of their assuming the metamorphic character. Principles of Geology or, The Modern Changes of the Earth and its Inhabitants Considered as Illustrative of Geology Along this route, the degree of metamorphism gradually increases from sedimentary parent rock to low-grade metamorphic rock, then higher-grade metamorphic rock, and eventually the igneous core. An Introduction to Geology 2017-01-01T00:00:00Z The intruding granite, which predominates in the north-west, has frequently united with the metamorphic series to form composite gneiss. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 6 "Dodwell" to "Drama" Diopside is the characteristic pyroxene of metamorphic rocks, occurring especially in crystalline limestones, and often in association with garnet and epidote. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 5 "Dinard" to "Dodsworth" Wherever the heated material came into contact with aqueous rocks it transformed them, for a foot or more, into crystalline, metamorphic rocks. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place One of the metamorphic or crystalline stratified rocks of the hypogene class, which is characterized by being composed of a large proportion of mica united with quartz. Principles of Geology or, The Modern Changes of the Earth and its Inhabitants Considered as Illustrative of Geology Because rock is a good insulator, the temperature of the descending oceanic slab increases slowly relative to the more rapidly increasing pressure, creating a metamorphic environment of high pressure and low temperature. An Introduction to Geology 2017-01-01T00:00:00Z Their rhizomes are set in black mould accumulated in hollows of the metamorphic slates beside the pools, where they are well watered without being subjected to flood action. My First Summer in the Sierra Occasionally diorites have a parallel banded or foliated structure, but these must not be confounded with the epidiorites, which are metamorphic rocks and also have a conspicuous foliation. Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 5 "Dinard" to "Dodsworth" They are what the geologist calls metamorphic, which means changed. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place It is, however, not impossible that the metamorphic series includes also some of the Lias. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 6 "Coucy-le-Château" to "Crocodile" In the lowest parts of the Grand Canyon are the oldest sedimentary formations, with igneous and metamorphic rocks at the bottom. An Introduction to Geology 2017-01-01T00:00:00Z The rock is mostly granite, with some small piles and crests rising here and there in picturesque pillared and castellated remnants of red metamorphic slates. My First Summer in the Sierra Mountains of the Secondary Age were often made of Primary sedimentary rocks, or of Primary igneous rocks, so much changed that geologists call them metamorphic rocks. The Boy With the U.S. Miners As bricks vary in colour and quality according to the materials that compose them, so the metamorphic rocks differ. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place The granite is not the oldest of the Cornish rocks; these are found in the Lizard peninsula and are represented by serpentine, gabbro and metamorphic schists. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 4 "Coquelin" to "Costume" The photo of the Grand Canyon here show strata that were originally deposited in a flat layer on top of older igneous and metamorphic “basement” rocks, per the original horizontality principle. An Introduction to Geology 2017-01-01T00:00:00Z In the older rocks, basalt has often undergone decomposition into melaphyre; and amongst the metamorphic rocks it has been changed into diorite or hornblende rock; the augite having been converted into hornblende. Volcanoes: Past and Present But not a few controversial questions were dealt with, and the famous 'metamorphic theory' was advanced in opposition to the Wernerian hypothesis of 'primitive formations.' The Coming of Evolution The Story of a Great Revolution in Science If mica is a prominent element, the metamorphic rock is easily parted into overlapping, scaly layers. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place Half a mile of careful walking and jumping and we were on the ground again, at the base of the great cliff of metamorphic slate that crowned the summit. Alaska Days with John Muir A nonconformity occurs when sedimentary rock is deposited on top of igneous and metamorphic rocks as is the case with the contact between the strata and basement rocks at the bottom of the Grand Canyon. An Introduction to Geology 2017-01-01T00:00:00Z Modern researches have shown, too, that these metamorphic rocks are not, as was once supposed, all of the same age. Essays: Scientific, Political, & Speculative, Vol. I In the metamorphic regions, the trouble comes in the attempt to keep the soil on the hills, while in the flat lands the problem is to get proper drainage. The Negro Farmer The most enduring of all the rocks are the foundation granite, and the metamorphic rocks that lie next to them. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place The rock here is metamorphic, the soil worthless, the scenery rugged, yet mean. The Atlantic Monthly, Volume 14, No. 86, December, 1864 The sequence begins with the folded metamorphic gneiss on the bottom. An Introduction to Geology 2017-01-01T00:00:00Z The fundamental rocks brought up by this third and last upheaval are ophiolitic, and metamorphic, or primary, limestone, overlaid in some places by secondary formations. Rambles in the Islands of Corsica and Sardinia with Notices of their History, Antiquities, and Present Condition. It occurs as veins or lodes in metamorphic rocks, and it is this form of its presence in Australia, associated with gold, that has made the word of such daily occurrence. Austral English A dictionary of Australasian words, phrases and usages with those aboriginal-Australian and Maori words which have become incorporated in the language, and the commoner scientific words that have had their origin in Australasia These are the beds, sometimes miles in depth, called metamorphic rocks, formed by water, then transformed by heat. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place Some geologists confine the term metamorphism to the changes involved in contact and dynamic metamorphism, and call the resulting products metamorphic rocks. The Economic Aspect of Geology Metamorphic rocks are crystalline, but the processes of metamorphism may reset the clock and derived ages may represent a smear of different metamorphic events rather than the age of original crystallization. An Introduction to Geology 2017-01-01T00:00:00Z The metamorphic sediments have been pierced by acid and basic igneous intrusions, partly before and partly after the folding and metamorphism of the strata. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Now there is in most languages, but more particularly in those which are losing their consciousness or their vitality, what, by a name borrowed from geology, may be called a metamorphic process. Chips From A German Workshop. Vol. III. Essays on Literature, Biography, and Antiquities From aqueous rock materials, fire has produced a metamorphic rock. Earth and Sky Every Child Should Know Easy studies of the earth and the stars for any time and place Under the general heading of common rocks are included the ordinary igneous, sedimentary, and "metamorphic" rocks, and the unconsolidated clays, sands, and gravels characteristic of surface conditions, which are mined and quarried for commercial use. The Economic Aspect of Geology The rocks of these ranges are primary and metamorphic, and the scenery is bold. A Tramp's Notebook Resting unconformably on these metamorphic rocks, Old Red sandstone strata are met with in a few places. Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" As to Sarazin, it is most likely another Cornish word, which by a metamorphic process, has been slightly changed in order to yield some sense intelligible to Saxon speakers. Chips From A German Workshop. Vol. III. Essays on Literature, Biography, and Antiquities They are formed chiefly of crystalline gneissic and granitic rocks and some metamorphic schists and quarzite, with cretaceous and tertiary rocks of varying thickness along its southern edge. A Study of Recent Earthquakes Soil originate from rocks, igneous, sedimentary, and "metamorphic" by processes of weathering, and by the mixing of the altered mineral products with decayed plant remains or humus. The Economic Aspect of Geology Anthracite coal occurs in folded and metamorphic rocks. Commercial Geography A Book for High Schools, Commercial Courses, and Business Colleges But, it will be answered, the 30,000 feet of Azoic rocks, lying above the Primeval, are sedimentary to some extent: they are not all completely metamorphic: yet they are all destitute of fossils. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions To call this process metamorphic, using that name in the sense given to it by geologists, may at first sight seem pedantic and far-fetched. Chips From A German Workshop. Vol. III. Essays on Literature, Biography, and Antiquities Of the variety of problems that it presents one might mention the petrological questions connected with the intrusion of the great masses of granite, and their relation to the slates and associated metamorphic rocks. The Panjab, North-West Frontier Province, and Kashmir The general process of soil formation constitutes one of the most important phases of katamorphism—the destructive side of the metamorphic cycle, described in Chapter II. The Economic Aspect of Geology I believe that the geographical distribution of organic beings in past and present times, the kind of affinity linking them together, their so-called “metamorphic” and “abortive” organs, appear in favour of this view. The Foundations of the Origin of Species Two Essays written in 1842 and 1844 It is to the metamorphic formation that the abundance of mineral ores is due, and the igneous rocks which have given rise thereto—the granites, basalts, diorites, porphyries, and others. Mexico Its Ancient and Modern Civilisation, History, Political Conditions, Topography, Natural Resources, Industries and General Development No doubt he had observed some effects of fire in 'metamorphic' formations in his own vicinity. A Short History of Greek Philosophy The tract lying to the north-west of this dislocation is composed of the metamorphic rocks of the Eastern Highlands. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary" The net result of the metamorphic cycle, is, therefore, the accumulation of materials of the same kinds. The Economic Aspect of Geology Hornblende schists and beds of metamorphic limestone are rare. Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" To the geologist the fossiliferous limestones and the metamorphic rocks are alike of interest. The Sunny Side of Ireland How to see it by the Great Southern and Western Railway Rudely shaped chisel or celt of metamorphic schist. Illustrated Catalogue Of The Collections Obtained From The Indians Of New Mexico And Arizona In 1879 Second Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1880-81, Government Printing Office, Washington, 1883, pages 307-428 Stone hatchets rather well formed with blunt poll, distinct annular groove, and tapering blade; chiefly of basalt, three of metamorphic rock. 681-682. Illustrated Catalogue of the Collections Obtained from the Indians of New Mexico in 1880 Second Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1880-81, Government Printing Office, Washington, 1883, pages 429-466 Our discussion of these features will follow the order of rock genesis indicated in the description of the metamorphic cycle. The Economic Aspect of Geology These metamorphic phenomena, though important, are obscure, and their elucidation demands some knowledge of petrographic science, that branch of geology which considers the principles of rock formation. Outlines of the Earth's History A Popular Study in Physiography In the metamorphic rocks no organic remains have been found, and they are geologically below all the rocks that do contain traces of animal life. An Expository Outline of the "Vestiges of the Natural History of Creation" With a Notice of the Author's "Explanations:" A Sequel to the Vestiges Made from a very fine, hard metamorphic rock, small enough to be classed as a hatchet; crescent-shaped at the top. Illustrated Catalogue Of The Collections Obtained From The Indians Of New Mexico And Arizona In 1879 Second Annual Report of the Bureau of Ethnology to the Secretary of the Smithsonian Institution, 1880-81, Government Printing Office, Washington, 1883, pages 307-428 The formation is upper Silurian or lower Devonian, a transition to gneiss, but not highly metamorphic. To The Gold Coast for Gold, Vol. II A Personal Narrative These two main groups of changes together constitute the metamorphic cycle. The Economic Aspect of Geology And it was Darwinism, the theory of selection, that Virchow, in his denunciation, had in mind, rather than mere metamorphic development, the theory of descent, with which it is always confused! Socialism and Modern Science (Darwin, Spencer, Marx) It is called Chihoka. 18th May, 1866.—At our crossing place metamorphic rocks of a chocolate colour stood on edge; and in the country round we have patches of dolomite, sometimes as white as marble. The Last Journals of David Livingstone, in Central Africa, from 1865 to His Death, Volume I (of 2), 1866-1868 The rocks continued to show volcanic and metamorphic formation. Unknown Mexico, Volume 1 (of 2) A Record of Five Years' Exploration Among the Tribes of the Western Sierra Madre; In the Tierra Caliente of Tepic and Jalisco; and Among the Tarascos of Michoacan It is simply an ordinary Jurassic limestone altered by subsequent metamorphic action. Roman Mosaics Or, Studies in Rome and Its Neighbourhood The alternation of constructive and destructive changes of the metamorphic cycle, and the repetitions of the cycle itself, periodically work over the earth materials into new forms. The Economic Aspect of Geology But all this merely concerns such or such a detail of Darwinism, while the fundamental theory of metamorphic organic development remains impregnable. Socialism and Modern Science (Darwin, Spencer, Marx) There is also a class of rocks, called metamorphic rocks, including some kinds of marble. Young Folks' Library, Volume XI (of 20) Wonders of Earth, Sea and Sky The Geological Survey recognizes a special group of 'transition' rocks between the metamorphic and the Vindhyan series under the name of the Gwālior area. Rambles and Recollections of an Indian Official The clay slate is metamorphic, being almost entirely composed of mica. The Commercial Products of the Vegetable Kingdom Considered in Their Various Uses to Man and in Their Relation to the Arts and Manufactures; Forming a Practical Treatise & Handbook of Reference for the Colonist, Manufacturer, Merchant, and Consumer, on the Cultivation, Preparation for Shipment, and Commercial Value, &c. of the Various Substances Obtained From Trees and Plants, Entering into the Husbandry of Tropical and Sub-tropical Regions, &c. The metamorphic cycle becomes a logical and convenient geologic basis for correlating, interpreting, and classifying mineral products. The Economic Aspect of Geology The same materials yield the most dissimilar products, a fact that is of the greatest importance in reference to the study of the nature of erupted rocks, and of the metamorphic action which they occasion. COSMOS: A Sketch of the Physical Description of the Universe, Vol. 1 Nowhere are the evidences of this denudation more apparent than in North and South America, where granitic or metamorphic rocks cover an area hardly less than that of all Europe. Darwinism (1889) Statuary marble, and most of the celebrated foreign marbles, are "metamorphic" rocks, of a highly crystalline nature, and having all traces of their primitive organic structure obliterated. The Ancient Life History of the Earth A Comprehensive Outline of the Principles and Leading Facts of Palæontological Science Miraculously metamorphic was its action upon the a�rial travellers. Punch Among the Planets Ores of certain metals, such as iron, occur in almost every phase of the metamorphic cycle,—as igneous after-effects, as weathered products, as sediments, and as schists. The Economic Aspect of Geology The slate, however, becomes more and more metamorphic as we go up, until it passes into what much resembles trap. The Lake of the Sky Lake Tahoe in the High Sierras of California and Nevada, its History, Indians, Discovery by Frémont, Legendary Lore, Various Namings, Physical Characteristics, Glacial Phenomena, Geology, Single Outlet, Automobile Routes, Historic Towns, Early Mining Excitements, Steamer Ride, Mineral Springs, Mountain and Lake Resorts, Trail and Camping Out Trips, Summer Residences, Fishing, Hunting, Flowers, Birds, Animals, Trees, and Chaparral, with a Full Account of the Tahoe National Forest, the Public Use of the Water of Lake Tahoe and Much Other Interesting Matter There is no igneous, no metamorphic rock here; nothing but limestone of the Jurassic formation. Wanderings by southern waters, eastern Aquitaine When at all of a pronounced character, the result of metamorphic action is invariably the obliteration of any fossils which might have been originally present in the rock. The Ancient Life History of the Earth A Comprehensive Outline of the Principles and Leading Facts of Palæontological Science The material of this inhospitable coast is a hard metamorphic schist which bids defiance to time and weather. Life of St. Declan of Ardmore and Life of St. Mochuda of Lismore The principal copper ores originate in the earlier stages of the metamorphic cycle, in close association with igneous activity. The Economic Aspect of Geology From this point the canyon bed and lower walls are granite, but the highest peaks are still a dark, splintery, metamorphic slate. The Lake of the Sky Lake Tahoe in the High Sierras of California and Nevada, its History, Indians, Discovery by Frémont, Legendary Lore, Various Namings, Physical Characteristics, Glacial Phenomena, Geology, Single Outlet, Automobile Routes, Historic Towns, Early Mining Excitements, Steamer Ride, Mineral Springs, Mountain and Lake Resorts, Trail and Camping Out Trips, Summer Residences, Fishing, Hunting, Flowers, Birds, Animals, Trees, and Chaparral, with a Full Account of the Tahoe National Forest, the Public Use of the Water of Lake Tahoe and Much Other Interesting Matter Beyond, the metamorphic rock gave place to red sandstone, and the ground sloped down into the little coal basin of Firmi. Wanderings by southern waters, eastern Aquitaine The so-called "primitive gneiss" of Norway appears to belong to the Laurentian, and the Page 67 ancient metamorphic rocks of Bohemia and Bavaria may be regarded as being approximately of the same age. The Ancient Life History of the Earth A Comprehensive Outline of the Principles and Leading Facts of Palæontological Science I may observe, that in the case of the frozen snow, the columnar structure must be owing to a "metamorphic" action, and not to a process during deposition. The Voyage of the Beagle They are all related to the earlier stages of the metamorphic cycle and occur in close genetic association with igneous activity. The Economic Aspect of Geology The material of this inhospitable coast is a hard metamorphic schist which bids defiance to time and weather. The Life of St. Declan of Ardmore Archaean.—The metamorphic rocks compose the main mass of the tableland, and are exposed in every deep valley in Tigre and along the valley of the Blue Nile. The Project Gutenberg Encyclopedia Volume 1 of 28 Owing to their metamorphic condition, geologists long despaired of ever detecting any traces of life in the vast pile of strata which constitute the Laurentian System. The Ancient Life History of the Earth A Comprehensive Outline of the Principles and Leading Facts of Palæontological Science Veins of auriferous quartz are found throughout the central chain, the richest lodes being encountered in metamorphic rocks near crystalline formations. Santo Domingo A Country with a Future The sedimentary iron ores in general evidently represent an advanced stage of katamorphism, and illustrate the tendency of this phase of the metamorphic cycle toward simplification and segregation of certain materials. The Economic Aspect of Geology Where metamorphic rocks are found, the surface is broken and hilly, rising to elevations of 600 feet or more above the lake; in this respect unlike the southern shore, which is low and flat. By Water to the Columbian Exposition The metamorphic rocks have been invaded by igneous materials, some before, and by far the larger series after the folding of the strata. The Project Gutenberg Encyclopedia Volume 1 of 28 As regards its mineral characters, the Laurentian series is composed throughout of metamorphic and highly crystalline rocks, which are in a high degree crumpled, folded, and faulted. The Ancient Life History of the Earth A Comprehensive Outline of the Principles and Leading Facts of Palæontological Science The mountains along this day's journey were composed, near the river, of a slaty calcareous rock in a metamorphic condition. The Exploring Expedition to the Rocky Mountains, Oregon and California To which is Added a Description of the Physical Geography of California, with Recent Notices of the Gold Region from the Latest and Most Authentic Sources In short, the question was settled on the scientific principles of origin of ores and of metamorphic geology. The Economic Aspect of Geology The diamond is found in the débris of metamorphic rocks in many countries, and is probably one of the evolved products of the distillation of organic matter they once contained. Scientific American Supplement, No. 362, December 9, 1882 The table, with its igneous crystallizations, lies upon the metamorphic rock. Two Summers in Guyenne The chemical comparison of the metamorphic with the normal rock pointed out distinctly the nature of the substances acquired or lost. Scientific American Supplement, No. 299, September 24, 1881 Brown metamorphic slate, close-grained in places, dips away from the inlet, presenting edges to ice-action, which has given rise to a singularly beautiful and striking surface, polished and grooved and fluted. Travels in Alaska Iron ores are represented in nearly all phases of the metamorphic cycle, but the principal commercial values have been produced by processes of weathering and sedimentation at and near the surface. The Economic Aspect of Geology They are the same in material, but only changed into new forms and combinations; hence they have been called by Mr. Lyell, metamorphic rocks. Vestiges of the Natural History of Creation Both the valley and surrounding country are destitute of trees, and bold hills of metamorphic sandstone frequently jut out into the valley, and terminate in perpendicular cliffs 200 or 300 feet high. Journals of Australian Explorations But just as a silicious deposit may be metamorphosed into opal or quartzite, and chalk into marble, so known metamorphic agencies may metamorphose clay into schist, clay-slate, slate, gneiss, or even granite. Discourses Biological and Geological Essays This glacial drift reposes near the mountains on ancient metamorphic rocks and farther from them on marine Pliocene strata. The Antiquity of Man Examination of the iron formations results in elimination of large parts of them, because their metamorphic condition is not favorable to ore concentration. The Economic Aspect of Geology The "erratics" comprised a great variety of metamorphic and igneous rocks, and, on a more limited scale, sedimentary types. The Home of the Blizzard Being the Story of the Australasian Antarctic Expedition, 1911-1914 These afterward collected into larger masses, which have been variously changed by subsequent metamorphic action, and broken up by repeated mutual impact, and often again collected together and solidified. Ragnarok : the Age of Fire and Gravel And hence it may not be hazardous to conclude that very ordinary metamorphic agencies may convert these polar caps into a form of quartzite. Discourses Biological and Geological Essays Pierce could feel a metamorphic agency at work in the town; already new habits of life were crystallizing among its citizens; and beneath its whirlpool surface new forms were in the making. The Winds of Chance Talc deposits consist of lenses and bands in metamorphic limestones, schists, and gneisses of ancient age. The Economic Aspect of Geology The object of each metamorphic or developmental epoch is a critical readjustment of the organism, in order to insure the greatest possible amount of health for each subsequent period of life. The Four Epochs of Woman's Life; a study in hygiene How do the Triassic sandstones and shales compare in hardness with the igneous and metamorphic rocks about them? The Elements of Geology It will be useful here to add other illustrations, showing that a texture undistinguishable from that which characterises the more crystalline metamorphic formations has actually been superinduced in strata once fossiliferous. The Student's Elements of Geology I have also seen it in thin veins of metamorphic rocks, glittering like silver, and when scratched with a knife, it resolves into a downy condition like scraped cotton. Cyprus, as I Saw It in 1879 Here, also, a new appearance was presented in some extensive and level banks of alluvium or detritus of the neighbouring metamorphic rocks; but I neglected to observe whether it was stratified or not. Geological Observations on South America These pseudo-fragments of shale will perhaps explain, in some cases, the origin of apparently extraneous fragments in crystalline metamorphic rocks. Volcanic Islands Graphite, a soft black mineral composed of carbon and used in the manufacture of lead pencils and as a lubricant, occurs widely in the metamorphic pre- Cambrian rocks. The Elements of Geology A considerable lapse of time must intervene between the formation of Plutonic and metamorphic rocks in the nether regions and their emergence at the surface. The Student's Elements of Geology These are nearly eleven inches in diameter, while in the fort of Kyrenia the stone shot are still existing, nineteen inches in diameter, composed of an exceedingly hard and heavy metamorphic rock. Cyprus, as I Saw It in 1879 Let us now turn to the foliation of the metamorphic schists, a subject which has been much less attended to. Geological Observations on South America Mica, in rounded nodules. -origin in metamorphic slate. -radiating form of. Volcanic Islands The Lower and the Upper Huronian consist in the main of old sea muds and sands and limy oozes now changed to gneisses, schists, marbles, quartzites, slates, and other metamorphic rocks. The Elements of Geology Fossiliferous Strata near intrusive Masses of Granite converted into Rocks identical with different Members of the metamorphic Series. The Student's Elements of Geology Eruptive rocks had burst through the chalk, producing interesting metamorphic phenomena. Cyprus, as I Saw It in 1879 La Plata, metamorphic and old volcanic rocks of. Geological Observations on South America Quartz, crystals of, in beds alternating with obsidian. -crystallised in sandstone. -fusibility of. -rock, mottled from metamorphic action with earthy matter. Volcanic Islands In many cases, however, the early history of a metamorphic rock can be deciphered. The Elements of Geology In the course of such changes many of the existing sedimentary strata would suffer greatly by denudation, others might assume a metamorphic structure, or become melted down into Plutonic and volcanic rocks. The Student's Elements of Geology This is very odd, but I suspect that great metamorphic areas are generally derived from the metamorphosis of clay-slate, and not from alternating layers of ordinary sedimentary matter. More Letters of Charles Darwin — Volume 2 This island lies between the Chonos and Chiloe groups: it is about eight hundred feet high, and perhaps has a nucleus of metamorphic rocks. Geological Observations on South America Where the metamorphic change has been greatest, two varieties occur. Volcanic Islands These few examples must suffice of the great class of metamorphic rocks. The Elements of Geology To this subject, however, I shall again revert, in Chapter 35, where the chronological relations of the metamorphic rocks are pointed out. The Student's Elements of Geology Your expectation of the metamorphic schists sending veins into neighbouring rocks is quite new to me; but I much doubt whether you have any right to assume fluidity from almost any amount of molecular change. More Letters of Charles Darwin — Volume 2 The metamorphic action, even in the lower strata, has certainly been far less here than in Central Chile. Geological Observations on South America This is a process which is now fully recognised as having been a potent factor in the production of the metamorphic rock, and has been called by more recent writers "dynamo-metamorphism." Volcanic Islands The gold-bearing quartz veins of California traverse the metamorphic slates of the Sierra Nevada Mountains. The Elements of Geology Some of these hornblendic masses may really have been volcanic rocks, which have since assumed a more crystalline or metamorphic texture. The Student's Elements of Geology I believe even such might be converted into an ordinary varying mass of metamorphic schists. More Letters of Charles Darwin — Volume 2 Finally, I may observe, that the presence of metallic veins seems obviously connected with the presence of intrusive rocks, and with the degree of metamorphic action which the different districts of Chile have undergone. Geological Observations on South America In the central parts of Chili the structure of the lower beds is rendered very obscure by the metamorphic action which has rendered even the coarsest conglomerates porphyritic. More Letters of Charles Darwin — Volume 1 So again the making out of cleavage and the foliation of the metamorphic rocks. Life and Letters of Charles Darwin — Volume 2 If complex and enigmatical appearances did not present themselves, it would be a serious objection to the metamorphic theory. The Student's Elements of Geology The so-called beds in the metamorphic schists, so unlike common cleavage laminae, seems the best, or at least one argument against such a suspicion. More Letters of Charles Darwin — Volume 2 At the base of the hill there are syenites, a granular mixture of quartz and feldspar, and harsh quartzose rocks, all belonging to the basal metamorphic series. Geological Observations on South America It is a primordial chain—that is to say, anterior to all organic and metamorphic creation. In Search of the Castaways; or the Children of Captain Grant Like Scrope, Darwin recognised the close analogy between the structure of these rocks and those of metamorphic origin—a subject which he followed out in the volume "Geological Observations on South America". Darwin and Modern Science The gold found in the United States, in the mountainous parts of Virginia, North and South Carolina, and Georgia, occurs in metamorphic Silurian strata, as well as in auriferous gravel derived from the same. The Student's Elements of Geology He saw, what generations of predecessors had blindly refused to see, that the face of nature everywhere, instead of being rigid and immutable, is perennially plastic, and year by year is undergoing metamorphic changes. A History of Science — Volume 3 From the Jaula to the plain, the stratification has been in most places obliterated, except near the tops of some of the mountains; and the metamorphic action has been extremely great. Geological Observations on South America It is drawn from the phenomena presented by all kinds of rocks, aqueous, igneous, metamorphic. History of the Conflict Between Religion and Science Stratification, diagonal or cross. —, different forms described. — of metamorphic rocks considered. The Student's Elements of Geology Age of metamorphic rocks. — of Plutonic rocks. — of strata, tests of. — of volcanic rocks. The Student's Elements of Geology Whether "primitive" or metamorphic, however, these Canadian rocks, and analogous ones beneath the fossiliferous strata of other countries, are the oldest portions of the earth's crust of which geology has any present knowledge. A History of Science — Volume 3 Some of the layers of the black siliceous slate contained irregular angular fragments of imperfect pitchstone, which I believe, as in the Uspallata range, has originated in a metamorphic process. Geological Observations on South America It is also supported by such facts as the small mean density of the earth, the increasing temperature at increasing depths, the phenomena of volcanoes and injected veins, and those of igneous and metamorphic rocks. History of the Conflict Between Religion and Science It has a strike from north-west to south-east, nearly at right angles to the metamorphic strata of the Grampians. The Student's Elements of Geology The metamorphic rocks are not indicated in this diagram: but the student will infer, from what is said in Chapters 31 and 33, that some portions of the stratified formations, Nos. The Student's Elements of Geology On this Laurentian gneiss, in parts of the western Highlands, the Lower Cambrian and various metamorphic rocks rest unconformably. The Student's Elements of Geology Westward of this main range, the metamorphic schists are foliated, though less plainly, in the same direction, which is likewise common to the zone of old erupted trappean rocks, forming the outermost islets. Geological Observations on South America Lime, scarcity of, in metamorphic rocks. — in solution, source of. The Student's Elements of Geology Silurian, derivation of the name. —, granite of Norway. —, metamorphic, of North Highlands. — rocks, classification of. — strata of the continent of Europe. — strata of United States. — volcanic rocks. The Student's Elements of Geology Nor should it be forgotten that, as a general rule, the less crystalline rocks do really occur in the upper, and the more crystalline in the lower part of each metamorphic series. The Student's Elements of Geology When discussing the ages of the Plutonic rocks, we have seen that examples occur of various primary, secondary, and tertiary deposits converted into metamorphic strata near their contact with granite. The Student's Elements of Geology In some of the jaspery layers, and in some of the black siliceous slaty bands, there were irregular seams of imperfect pitchstone, undoubtedly of metamorphic origin, and other seams of brown, crystalline limestone. Geological Observations on South America Cleavage explained. —, crystalline theory of. —, mechanical theory of. — of metamorphic rocks. The Student's Elements of Geology The mica in recent volcanic rocks, gabbros, and diorites is usually Biotite, while that so common in metamorphic limestones is usually, if not always, Phlogopite. The Student's Elements of Geology These Scotch metamorphic strata are of gneiss, mica-schist, and clay-slate of vast thickness, and having a strike from north-east to south-west almost at right angles to that of the older Laurentian gneiss before mentioned. The Student's Elements of Geology Connection between the Absence of Organic Remains and the Scarcity of calcareous Matter in metamorphic Rocks. The Student's Elements of Geology Looking to the basal, metamorphic, and plutonic rocks of the continent, the areas formed of them are likewise vast; and their planes of cleavage and foliation strike over surprisingly great spaces in uniform directions. Geological Observations on South America According to the theory adopted in the last chapter, the metamorphic strata have been deposited at one period, and have become crystalline at another. The Student's Elements of Geology Whatever hypothesis we adopt, the phenomena establish beyond a doubt the possibility of the development of the metamorphic structure in a tertiary deposit in planes parallel to those of stratification. The Student's Elements of Geology Even when these are found, we can not assume that there never were any antecedent strata containing organic remains, which may have become metamorphic. The Student's Elements of Geology Such clay-slates, in fact, are variable in composition, and sometimes alternate with fossiliferous strata, so that they may be said to belong almost equally to the sedimentary and metamorphic order of rocks. The Student's Elements of Geology In one part, there were many pebbles of the common metamorphic porphyries of the Cordillera: and near the base of the cliff, I observed a single rounded boulder of greenstone, nearly a yard in diameter. Geological Observations on South America In the present work, therefore, the four great classes of rocks, the aqueous, Plutonic, volcanic, and metamorphic, will form four parallel, or nearly parallel, columns in one chronological table. The Student's Elements of Geology It may perhaps be suggested that some metamorphic strata, and some granites, may be anterior in date to the oldest of the primary fossiliferous rocks. The Student's Elements of Geology Foliation may be used for those alternating layers or plates of different mineralogical nature of which gneiss and other metamorphic schists are composed. The Student's Elements of Geology The gases and water which are made to penetrate these cracks are probably rendered the more effective as metamorphic agents by increased temperature derived from the interior. The Student's Elements of Geology For more than two hundred miles northward of Navidad, the coast consists of plutonic and metamorphic rocks, with the exception of some quite insignificant superficial beds of recent origin. Geological Observations on South America Fossiliferous Strata near intrusive Masses of Granite converted into Rocks identical with different Members of the metamorphic Series. The Student's Elements of Geology Hence there are four great classes of rocks considered in reference to their origin— the aqueous, the volcanic, the Plutonic, and the metamorphic. The Student's Elements of Geology Difficulty of ascertaining the Age of metamorphic Strata. The Student's Elements of Geology Connection between the Absence of Organic Remains and the Scarcity of calcareous Matter in metamorphic Rocks. The Student's Elements of Geology It rests, wherever any underlying formation can be seen, on plutonic and metamorphic rocks. Geological Observations on South America Aqueous, Plutonic, volcanic, and metamorphic Rocks considered chronologically. The Student's Elements of Geology Aqueous, Plutonic, volcanic, and metamorphic Rocks considered chronologically. The Student's Elements of Geology Fossils, arrangement of, in strata. —, destruction of, in older formations. —, fresh-water and marine. — obliterated by metamorphic action. —, recent, and Post-pliocene. — of the drift. — of the Crags. The Student's Elements of Geology Difficulty of ascertaining the Age of metamorphic Strata. The Student's Elements of Geology To this subject I shall refer again when treating of the metamorphic rocks, and of the slaty and jointed structure. The Student's Elements of Geology |
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