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Slate

Metamorphic rock
Slate
Composition
Primary	quartz, muscovite/illite
Secondary	biotite, chlorite, hematite, pyrite

Slate Macro (~ 6 cm long and ~ 4 cm high)

Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism.

The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering. When expertly "cut" by striking with a specialized tool in the quarry, many slates will form smooth flat sheets of stone which have long been used for roofing and floor tiles and other purposes. Slate is frequently grey in color, especially when seen, en masse, covering roofs. However, slate occurs in a variety of colors even from a single locality; for example, slate from North Wales can be found in many shades of grey, from pale to dark, and may also be purple, green or cyan. Slate is not to be confused with shale, from which it may be formed, or schist. Ninety percent of Europe's natural slate used for roofing originates from Spain.^[1]

The word "slate" is also used for some objects made from slate. It may mean a single roofing slate, or a writing slate, traditionally a small piece of slate, often framed in wood, used with chalk as a notepad or noticeboard etc., and especially for recording charges in pubs and inns. The phrase "clean slate" or "blank slate" comes from this use.

Historical mining terminology[link]

Before the mid-19th century, the terms slate, shale and schist were not sharply distinguished.^[2] In the context of underground coal mining, the term slate was commonly used to refer to shale well into the 20th century.^[3] For example, roof slate refers to shale above a coal seam, and draw slate refers to roof slate (shale) that falls from the mine roof as the coal is removed.^[4]

Mineral composition[link]

Slate is mainly composed of quartz and muscovite or illite, often along with biotite, chlorite, hematite, and pyrite and, less frequently, apatite, graphite, kaolin, magnetite, tourmaline, or zircon as well as feldspar. Occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids, which appear as ellipses when viewed on a cleavage plane of the specimen.

Uses[link]

Slate roof.

Slate-faced church and homes.

Slate in buildings[link]

Slate can be made into roofing slates, which are installed by a slater. Slates are often erroneously called shingles, as shingles made from stone are technically tiles. Slate has two lines of breakability: cleavage and grain, which make it possible to split the stone into thin sheets. When broken, slate retains a natural appearance while remaining relatively flat and easily stackable.

Slate is particularly suitable as a roofing material as it has an extremely low water absorption index of less than 0.4%. Its low tendency to absorb water also makes it very resistant to frost damage and breakage due to freezing.

Slate roof tiles are usually fixed using either nail fixing, or the hook fixing method as is common with Spanish slate. In the UK, nailing is typically done with double nails onto timber battens (England and Wales) or nailed directly onto timber sarking boards (Scotland and Northern Ireland). Nails will traditionally be copper, although modern alloy and stainless steel alternatives are known. Both these methods, if used properly, will provide a long-lasting weathertight roof with a typical lifespan of around 80–100 years.

Some mainland European slate suppliers suggest that using hook fixing means that:^[5]

• Areas of weakness on the tile are fewer since no holes have to be drilled
• Roofing features such as valleys and domes are easier to create since narrow tiles can be used
• Hook fixing is particularly suitable in regions subject to severe weather conditions since there is a greater resistance to wind uplift as the lower edge of the slate is secured.

The metal hooks are, however, visible and may be unsuitable for historic properties.

Slate tiles are often used for interior and exterior flooring, stairs, walkways and wall cladding. Tiles are installed and set on mortar and grouted along the edges. Chemical sealants are often used on tiles to improve durability and appearance, increase stain resistance, reduce efflorescence, and increase or reduce surface smoothness. Tiles are often sold gauged, meaning that the back surface is ground for ease of installation. Slate flooring can be slippery when used in external locations subject to rain. Slate tiles were used in 19th century UK building construction (apart from roofs) and in slate quarrying areas such as Bethesda, Wales there are still many buildings wholly constructed of slate. Slates can also be set into walls to provide a rudimentary damp-proof membrane. Small offcuts are used as shims to level floor joists. In areas where slate is plentiful it is also used in pieces of various sizes for building walls and hedges, sometimes combined with other kinds of stone. In modern homes slate is often used as table coasters.

Slate gravestone in Hingham, Massachusetts

Other uses[link]

A grave with inscription on slate.

Because it is a good electrical insulator and fireproof, it was used to construct early-20th century electric switchboards and relay controls for large electric motors. Fine slate can also be used as a whetstone to hone knives.

Due to its thermal stability and chemical inertness, slate has been used for laboratory bench tops and for billiard table tops. In 18th- and 19th-century schools, slate was extensively used for blackboards and individual writing slates for which slate or chalk pencils were used.

In areas where it is available, high-quality slate is used for tombstones and commemorative tablets. In some cases slate was used by the ancient Maya civilization to fashion stelae.

Slate extraction[link]

Exhibition Slate mine at Fell, Germany.

Historical Pit Vogelsberg 1 at Fell

In Eurasia[link]

Slate-producing regions in Europe include Wales (see slate industry in Wales), Cornwall (famously the village of Delabole), Cumbria (see Burlington Slate Quarries, Honister Slate Mine and Skiddaw Slate) in the United Kingdom; parts of France (Anjou, Loire Valley, Ardennes, Brittany, Savoie); Belgium (Ardennes); Liguria in northern Italy, especially between the town of Lavagna (which means chalkboard in Italian) and Fontanabuona valley; Portugal especially around Valongo in the north of the country; Spain see Slate Industry in Spain; Germany's (Moselle River-region, Hunsrück, Eifel, Westerwald, Thuringia and north Bavaria); Alta, Norway (actually schist not a true slate) and Galicia. Some of the slate from Wales and Cumbria is colored slate (non-blue): purple and formerly green in Wales and green in Cumbria. China has vast slate deposits; in recent years its export of finished and unfinished slate has increased, it has slate in various colors.

In the Americas[link]

Slate is abundant in Brazil (the second-biggest producer of slate) around Papagaios in Minas Gerais (responsible for 95% of the extraction of slate in Brazil). An independent report by Consultant Geologist J. A. Walsh describes how certain products originating from Brazil on sale in the UK, are not entitled to bear the CE mark.^[6]

Other areas known for slate production are the east coast of Newfoundland, the Slate Belt of Eastern Pennsylvania, Buckingham County Virginia (Buckingham Slate), and the Slate Valley of Vermont and New York, where colored slate is mined in the Granville, New York area.

A major slating operation existed in Monson, Maine, during the late 19th and early 20th centuries. The slate found in Monson is usually a dark purple to blackish color, and many local structures are still roofed with slate tiles. The roof of St. Patrick's Cathedral was made of roofing slate from Monson, as was the headstone of John F. Kennedy.^[7]

Slate is also found in the Arctic and was used by the Inuit to make the blades for ulus.

Fossils[link]

Shale can metamorphose into slate; sometimes the fossils may remain intact.

Because slate was formed in low heat and pressure, compared to a number of other metamorphic rocks, some fossils can be found in slate; sometimes even microscopic remains of delicate organisms.^[8]

See also[link]

• List of rock types
• Shale
• Tile
• National Slate Museum
• Fell Exhibition Slate Mine
• Slate industry in Wales
• Slate and stylus
• Slate Industry in Spain

References[link]

• Page, William (ed.) (1906). The Victoria History of the County of Cornwall; vol. I. (Chapter on quarries.) Westminster: Constable.

Further reading[link]

• Hudson, Kenneth (1972). Building Materials; "Chapter 2: Stone and Slate". London: Longman, pp. 14–27. ISBN 0-582-12791-2.

External links[link]

Wikimedia Commons has media related to: Slate

• AditNow—Photographic database of mines
• John T F Turner - A Familiar Description of the Old Delabole Slate Quarries, 1864
• Granville Slate Museum
• Hower’s Lightning Slate Reckoner (1884/1904), by F. M. Hower, Cherryville, Penn., on Stone Quarries and Beyond (PDF/18.95 MB)

Steven Arthur Pinker
Steven Pinker in 2011
Born	(1954-09-18) September 18, 1954 (age 57) Montréal, Québec, Canada
Residence	United States of America
Citizenship	Canadian
Fields	Evolutionary psychology, experimental psychology, cognitive science, linguistics, visual cognition
Alma mater	Dawson College, McGill University, Harvard University
Known for	How the Mind Works, The Blank Slate
Influences	Noam Chomsky, Thomas Sowell, Leda Cosmides, John Tooby, Richard Dawkins, Thomas Schelling[1]
Notable awards	Troland Award (2003, National Academy of Sciences), Henry Dale Prize (2004, Royal Institution), Walter P. Kistler Book Award (2005), Humanist of the Year award (2006, issued by the AHA), George Miller Prize (2010, Cognitive Neuroscience Society)
Website
http://www.stevenpinker.com/

Steven Pinker in Göttingen in 2010

Steven Arthur Pinker (born September 18, 1954, Montreal, Canada) is a Canadian-born experimental psychologist, cognitive scientist, linguist and popular science author. He is a Harvard College Professor and the Johnstone Family Professor in the Department of Psychology at Harvard University,^[2] and is known for his advocacy of evolutionary psychology and the computational theory of mind.

Pinker's academic specializations are visual cognition and psycholinguistics. His experimental subjects include mental imagery, shape recognition, visual attention, children's language development, regular and irregular phenomena in language, the neural bases of words and grammar, and the psychology of innuendo and euphemism. He published two technical books which proposed a general theory of language acquisition and applied it to children's learning of verbs. In his popular books, he has argued that language is an "instinct" or biological adaptation shaped by natural selection. He is the author of six books for a general audience: The Language Instinct (1994), How the Mind Works (1997), Words and Rules (2000), The Blank Slate (2002), The Stuff of Thought (2007), and The Better Angels of Our Nature (2011).

Biography[link]

Career[link]

Pinker was born in Montreal, Quebec, Canada in 1954, to a middle-class Jewish family. He graduated from Dawson College in 1971. He received a BA degree in psychology at McGill University in 1976, and then went on to earn his PhD degree in experimental psychology at Harvard University in 1979. He did research at the Massachusetts Institute of Technology (MIT) for a year, after which he became an assistant professor at Harvard and then Stanford University. From 1982 until 2003, Pinker taught at the Department of Brain and Cognitive Sciences at MIT, and eventually became the director of the Center for Cognitive Neuroscience, taking a one-year sabbatical at the University of California, Santa Barbara, in 1995-96. As of 2008, he is the Johnstone Family Professor of Psychology at Harvard.^[3] In June 2011 it was announced he would give lectures as a visiting professor at the New College of the Humanities, a private college in London.^[4]

Pinker was named one of Time Magazine's 100 most influential scientists and thinkers in the world in 2004^[5] and one of Prospect and Foreign Policy's 100 top public intellectuals in both years the poll was carried out, 2005^[6] and 2008;^[7] in 2010 and 2011 he was named by Foreign Policy magazine to its list of top global thinkers.^[8][9] His research in cognitive psychology has won the Early Career Award (1984) and Boyd McCandless Award (1986) from the American Psychological Association, the Troland Research Award (1993) from the National Academy of Sciences, the Henry Dale Prize (2004) from the Royal Institution of Great Britain, and the George Miller Prize (2010) from the Cognitive Neuroscience Society. He has also received honorary doctorates from the universities of Newcastle, Surrey, Tel Aviv, McGill, and the University of Tromsø, Norway. He was twice a finalist for the Pulitzer Prize, in 1998 and in 2003.

In January 2005, Pinker defended Lawrence Summers, President of Harvard University, whose comments about a gender gap in mathematics and science angered much of the faculty. Pinker noted that Summers's remarks, properly understood, could form the basis of a testable hypothesis. The remarks, Pinker said, claimed not that men are consistently smarter, but that there are "more idiots, [and] more geniuses" of the male gender.^[10]

On May 13, 2006, Pinker received the American Humanist Association's Humanist of the Year award for his contributions to public understanding of human evolution.^[11]

In 2009, Pinker wrote a highly critical review of Malcolm Gladwell's analytic methods in the New York Times.^[12] Gladwell published a rebuttal in the Times regarding Pinker's comments about the importance of IQ on teaching performance and by analogy, the effect, if any, of draft order on quarterback performance in the National Football League. Pinker then responded to Gladwell's rebuttal.^[13] The exchange prompted Advanced NFL Stats to step in and address the issue statistically, siding with Pinker in that draft order is indeed correlated with quarterback performance.^[14]

Pinker also serves on the Advisory Board of Secular Coalition for America and offers advice to Executive Director Sean Faircloth and the entire coalition on the acceptance and inclusion of nontheism in American life. ^[15]

The Committee for Skeptical Inquiry lists Pinker as one of their fellows. ^[16]

In February 2010 he was named to the Freedom From Religion Foundation's Honorary Board of distinguished achievers.^[17] Pinker appeared on the Colbert Report on 10/18/11.

Personal[link]

His father, a lawyer, first worked as a manufacturer's representative, while his mother was first a home-maker then a guidance counselor and high-school vice-principal. He has two younger siblings. His brother is a policy analyst for the Canadian government. His sister, Susan Pinker, is a psychologist and writer, author of The Sexual Paradox.^[18][19] Pinker married Nancy Etcoff in 1980 and they divorced in 1992; he married Ilavenil Subbiah in 1995 and they too divorced.^[20] His current wife is the novelist and philosopher Rebecca Goldstein.^[21] He has two stepdaughters: the novelist Yael Goldstein Love and the poet Danielle Blau.

He has said, "I was never religious in the theological sense... I never outgrew my conversion to atheism at 13, but at various times was a serious cultural Jew."^[22] As a teenager, he says he considered himself an anarchist until he witnessed civil unrest following a police strike in 1969.^[23] He has reported the result of a test of his political orientation that characterized him as "neither leftist nor rightist, more libertarian than authoritarian".^[24] Pinker confesses to having "experienced a primitive tribal stirring" after his genes were shown to trace back to the Middle East.^[25]

Theories of language and mind[link]

Pinker is known within psychology for his theory of language acquisition, his research on the syntax, morphology, and meaning of verbs, and his criticism of connectionist (neural network) models of language. In The Language Instinct (1994) he popularized Noam Chomsky's work on language as an innate faculty of mind, with the twist that this faculty evolved by natural selection as a Darwinian adaptation for communication, although both ideas remain controversial (see below). He also defends the idea of a complex human nature which comprises many mental faculties that are adaptive (and is an ally of Daniel Dennett and Richard Dawkins in many disputes surrounding adaptationism). Another major theme in Pinker's theories is that human cognition works, in part, by combinatorial symbol-manipulation, not just associations among sensory features, as in many connectionist models.

Written work[link]

Pinker's books, The Language Instinct, How the Mind Works, Words and Rules, The Blank Slate, and The Stuff of Thought combine cognitive science with behavioral genetics and evolutionary psychology. The Language Instinct has been criticized by Geoffrey Sampson in his book, The 'Language Instinct' Debate.^[26] The assumptions underlying the nativist view have also been subject to sustained criticism in Jeffrey Elman's Rethinking Innateness: A Connectionist Perspective on Development (Neural Networks and Connectionist Modeling), which defends the connectionist approach that Pinker has criticized.

Bibliography[link]

Wikiquote has a collection of quotations related to: Steven Pinker

Steven Pinker in 2005

Books[link]

• Language Learnability and Language Development (1984) ISBN 978-0-674-51055-5
• Visual Cognition (1985) ISBN 978-0-262-66178-2
• Connections and Symbols (1988) ISBN 978-0-262-66064-8
• Learnability and Cognition: The Acquisition of Argument Structure (1989) ISBN 978-0-262-66073-0
• Lexical and Conceptual Semantics (1992) ISBN 978-1-55786-354-6
• The Language Instinct (1994) ISBN 978-0-06-097651-4
• How the Mind Works (1997) ISBN 978-0-393-31848-7
• Words and Rules: The Ingredients of Language (1999) ISBN 978-0-465-07269-9
• The Blank Slate: The Modern Denial of Human Nature (2002) ISBN 978-0-670-03151-1
• The Best American Science and Nature Writing (editor and introduction author, 2004) ISBN 978-0-618-24698-4
• Hotheads (an extract from How the Mind Works, 2005) ISBN 978-0-14-102238-3
• The Stuff of Thought: Language as a Window into Human Nature (2007) ISBN 978-0-670-06327-7
• The Better Angels of Our Nature: Why Violence Has Declined (2011) ISBN 978-0-670-02295-3

Articles and essays[link]

• Pinker, S. (1991). "Rules of Language". Science 253 (5019): 530–535. DOI:10.1126/science.1857983. 
• Ullman, M.; Corkin, S.; Coppola, M.; Hickok, G.; Growdon, J. H.; Koroshetz, W. J.; Pinker, S. (1997). "A neural dissociation within language: Evidence that the mental dictionary is part of declarative memory, and that grammatical rules are processed by the procedural system". Journal of Cognitive Neuroscience 9: 289–299. 
• Pinker, S. (2003) "Language as an adaptation to the cognitive niche" In M. Christiansen & S. Kirby (Eds.), Language evolution: States of the Art New York: Oxford University Press.
• Pinker, S. (2005). "So How Does the Mind Work?". Mind and Language 20 (1): 1–24. DOI:10.1111/j.0268-1064.2005.00274.x. 
• Jackendoff, R.; Pinker, S. (2005). "The nature of the language faculty and its implications for evolution of language" (Reply to Fitch, Hauser, & Chomsky)". Cognition 97 (2): 211–225. DOI:10.1016/j.cognition.2005.04.006. 
• S. Pinker (2007), "In Defense of Dangerous Ideas" Chicago Sun-Times, July 15, 2007
• A number of Pinker's articles at Harvard

References[link]

External links[link]

Wikiquote has a collection of quotations related to: Steven Pinker

Wikimedia Commons has media related to: Steven Pinker

• Official website

Interviews

• In Depth interview with Pinker, November 2, 2008
• Steven Pinker discusses the "Games People Play: Indirect Speech as a Window into Social Relationships"
• Steven Pinker on The Hour
• Steven Pinker Multimedia. Extensive lists of audio and video files
• Biology vs. the Blank Slate Reason magazine interview with Pinker
• Live interview with Steven Pinker on The Blank Slate
• Radio interview on Philosophy Talk
• Online video interview with Pinker

TED talks

• Chalking it up to the blank slate, 2003
• The stuff of thought, 2005
• A brief history of violence, 2007

Debates

• The Two Steves Debate with Steven Rose
• The Science of Gender and Science Debate with Elizabeth Spelke