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Topography

Topography

Topography, a term in geography, has come to refer to the "lay of the land", or the physiogeographic characteristics of land in terms of elevation, slope, and orientation. "Terrain" is a similar concept, used more to describe the land itself than the study of it. "Relief" is often used to refer to the third dimension of a map whether in actuality (as in a "raised relief" map, or drawn, as with contours, hachures or shading) or the territory it describes. shading Topography is similar to topology, popularly thought of as the mathematical study of surfaces. This may help explain its adoption in the world of geographers. Its actual original meaning, from Greek "topos" (place) and "graphein" (to draw), relates to the description of places rather than broad regions, in topographic surveys. Most 18th and early 19th century national surveys did not record relief across the entire area of coverage, calculating only spot elevations at survey points. The United States Geological Survey (USGS) topographical survey maps included contour representation of relief, and so maps that show relief, especially with exact representation of elevation, came to be called topographic maps (or "topo" maps) in the United States, and the usage has spread internationally. The understanding of topography is critical for a number of reasons. In terms of environmental quality, agriculture, and hydrology, understanding the topography of an area enables the understanding of watershed boundaries, drainage characteristics, water movement, and impacts on water quality. Understanding topography also impinges on soil conservation, especially in agriculture. Contour plowing is an established practice of enabling sustainable agriculture on sloping land, and is the practice of plowing along topographic lines. Topography is critical militarily because it determines the ability of armed forces to take and hold areas, and to move troops and material into and through areas. Topography is important in determining weather patterns. Two areas in fairly close proximity geographically may differ radically in characteristics such as precipitation because of elevation differences or because of a "rain shadow" effect. Tectonic processes and erosional processes are the determiners of topography. Tectonic processes such as orogenies cause land to be elevated, and erosional (and weathering) processes cause land to be worn away to lower elevations.

Geography

)]] Geography is the study of the locational and spatial variation of both natural and human phenomena on Earth. The word derives from the Greek words Ge (γη) or Gaea (γεια), both meaning "Earth", and graphein (γραφειν) meaning "to describe" and "to write". Modern geography is a diverse discipline that draws influence from almost every other arena of knowledge. Geographers engage with other disciplines according to their particular research interests and, while subjects such as biology and economics have a powerful influence, there are geographers who use concepts taken from subjects such as sociology, psychology and sports science, among many others. Within the discipline there have been many long-running tensions among those seeking to define geography - whether as a 'science' or as a 'humanity', as a 'systematic' subject or 'regional' specialism and so forth - which at various times have come close to destroying geography as an academic discipline. Whilst profound differences do exist among geographers, the dual concepts of space and place provide a commonality of interest, which gives the subject a unique identity.

Structure of geography

William Hughes - who taught the geography of the Holy Lands to divinity students at King's College London - defined geography in an address in 1863: :"Mere place names are not geography. To know by heart a whole gazeteer full of them would not, in itself, constitute anyone a geographer. Geography has higher aims than this: it seeks to classify phenomena (alike of the natural and of the political world insofar as it treats of the latter) to compare, to generalise, to ascend from effects to causes and in doing so to trace out the great laws of nature and to mark their influence upon man. In a word, geography is a science, a thing not of mere names, but of argument and reason, of cause and effect." This was a specific rejection of geography as a merely descriptive discipline and also defined it as inclusive of both the physical world and the human. Within the discipline, however, there are many areas of specialism. Modern geographers tend to specialise in one of the broad branches (or sub-branches). However, most introductory geography syllabuses seek to ensure that geographers have at least working knowledge of the main focus of each branch of the subject.

Physical geography

Physical geography (or physiogeography) focuses on geography as an Earth science. It aims to understand the physical layout of the Earth, its weather and global flora and fauna patterns. Many areas of physical geography make use of geology, particularly in the study of weathering and sediment movement. Physical Geography can be divided into the following broad categories:
- Geomorphology
- Hydrology
- Glaciology
- Biogeography
- Climatology
- Pedology (soil study)
- Coastal/Marine studies
- Geodesy
- Palaeogeography
- Environmental Geography and management
- Landscape ecology Exact lines between these different areas are often difficult to draw. Sometimes Oceanography is included as a branch within physical geography, but is now considered a separate subject in its own right. Related topics: Atmosphere - Archipelago - Continent - Desert - Island - Landform - Ocean - Sea - River - Lake - Ecology - Soil - Timeline of geography, paleontology - Geostatistics - Environmental science - Oceanography - Environmental studies

Human geography

Human geography is a branch of geography that focuses on the study of patterns and processes that shape human interaction with various environments. It encompasses human, political, cultural, social, and economic aspects. While the major focus of human geography is not the physical landscape of the Earth (see Physical geography) it is hardly possible to discuss human geography without referring to the physical landscape on which human activities are being played out, and environmental geography is emerging as a link between the two. Human geography can be divided into broad categories, such as:
- Economic geography
- Development geography
- Population geography or Demography
-
- Urban geography
- Social geography
- Behavioral geography
- Cultural geography
- Political geography, including Geopolitics
-
- Historical geography
- Regional science
- Strategic geography
- Military geography
- Feminist geography
- Distinction between these fields of study have become increasingly blurred over time and the above list should not be considered definitive. Related topics: Countries of the world - Country - Nation - State - Personal union - Province - County - City - Municipality - Central place theory - Urban morphology

Socio-environmental geography

During the time of environmental determinism, geography was defined not as the study of spatial relationships, but as the study of how humans and the natural environment interact. Though environmental determinism has died out, there remains a strong tradition of geographers addressing the relationships between people and nature. There are two main subfields of socio-environmental geography:
- cultural and political ecology (CAPE) and
- risk-hazards research.

Cultural and political ecology

Cultural ecology grew out of the work of Carl Sauer in geography and a similar school of thought in anthropology. It examined how human societies adapt themselves to the natural environment. Sustainability science has been one important outgrowth of this tradition. Political ecology arose when some geographers used aspects of critical geography to look at relations of power and how they affect people's use of the environment. For example, an influential study by Michael Watts argued that famines in the Sahel are caused by the changes in the region's political and economic system as a result of colonialism and the spread of capitalism.

Risk-hazards research

Research on hazards began with the work of geographer Gilbert F. White, who sought to understand why people live in disaster-prone floodplains. Since then, the hazards field has expanded to become a multidisciplinary field examining both natural hazards (such as earthquakes) and technological hazards (such as nuclear reactor meltdowns). Geographers studying hazards are interested in both the dynamics of the hazard event and how people and societies deal with it.

Historical geography

This branch seeks to determine how cultural features of the multifarious societies across the planet evolved and came into being. Study of the landscape is one of many key foci in this field - much can be deduced about earlier societies from their impact on their local environment and surroundings. ; What's in a name? Historical geography and the Berkeley School "Historical Geography" can indeed refer to the reciprocal effects of geography and history on each other. But in the United States, it has a more specialized meaning: This is the name given by Carl Ortwin Sauer of the University of California, Berkeley to his program of reorganizing cultural geography (some say all geography) along regional lines, beginning in the first decades of the 20th Century. To Sauer, a landscape and the cultures in it could only be understood if all of its influences through history were taken into account: Physical, cultural, economic, political, environmental. Sauer stressed regional specialization as the only means of gaining expertise on regions of the world. Sauer's philosophy was the principal shaper of American geographic thought in the mid-20th century. Regional specialists remain in academic geography departments to this day. But many geographers feel that it harmed the discipline in the long run: Too much effort was spent on data collection and classification, and too little on analysis and explanation. Studies became more and more area specific as later geographers struggled to find places to make names for themselves. This probably led in turn to the 1950s crisis in Geography which nearly destroyed it as an academic discipline.

History of geography

:See main article: History of geography History of geography The Greeks are the first known culture to actively explore geography as a science and philosophy. Mapping by the Romans as they explored new lands added new techniques. During the Middle Ages, Arabs such as Idrisi, Ibn Batutta, and Ibn Khaldun maintained the Greek and Roman techniques and developed new ones. Following the journeys of Marco Polo, interest in geography spread throughout Europe. The great voyages of exploration in 16th and 17th centuries revived a desire for both accurate geographic detail, and more solid theoretical foundations. This period is also known as Great Geographical Discoveries. By the 18th century, geography had become recognized as a discrete discipline and became part of a typical university curriculum in Europe (especially Paris and Berlin). Over the past two centuries the quantity of knowledge and the number of tools has exploded. There are strong links between geography and the sciences of geology and botany, as well as economics, sociology and demographics. In the West during the 20th century, the discipline of geography went through four major phases: environmental determinism, regional geography, the quantitative revolution, and critical geography.
Geographic techniques
As spatial interrelationships are key to this synoptic science, maps are a key tool. Classical cartography has been joined by a more modern approach to geographical analysis, computer-based geographic information systems (GIS).
- Cartography studies the representation of the Earth's surface with abstract symbols (map making). Although other subdisciplines of geography rely on maps for presenting their analyses, the actual making of maps is abstract enough to be regarded separately. Cartography has grown from a collection of drafting techniques into an actual science. Cartographers must learn cognitive psychology and ergonomics to understand which symbols convey information about the Earth most effectively, and behavioral psychology to induce the readers of their maps to act on the information. They must learn geodesy and fairly advanced mathematics to understand how the shape of the Earth affects the distortion of map symbols projected onto a flat surface for viewing. It can be said, without much controversy, that cartography is the seed from which the larger field of Geography grew. Most geographers will cite a childhood fascination with maps as an early sign they would end up in the field. mathematics
- Geographic Information Systems deals with the storage of information about the Earth for automatic retrieval by a computer, in an accurate manner appropriate to the information's purpose. In addition to all of the other subdisciplines of geography, GIS specialists must understand computer science and database systems. GIS has so revolutionized the field of cartography that nearly all mapmaking is now done with the assistance of some form of GIS software.
- Geographic quantitative methods deal with numerical methods peculiar to (or at least most commonly found in) geography. In addition to spatial analyses, you are likely to find things like cluster analysis, discriminant analysis, and non-parametric statistical tests in geographic studies.
- Geographic qualitative methods, or ethnographic research techniques, are used by human geographers. In cultural geography there is a tradition of employing qualitative research techniques also used in anthropology and sociology. Participant Observation and in-depth interviews provide human geographers with qualitative data. In their study geographers use four interrelated approaches:
- Systematic - Groups geographical knowledge into categories that can be explored globally
- Regional - Examines systematic relationships between categories for a specific region or location on the planet.
- Descriptive - Simply specifies the locations of features and populations.
- Analytical - Asks why we find features and populations in a specific geographic area.
Related fields

Urban and regional planning
Urban planning and regional planning use the science of geography to assist in determining how to develop (or not develop) the land to meet particular criteria, such as safety, beauty, economic opportunities, the preservation of the built or natural heritage, etcetera. The planning of towns, cities and rural areas may be seen as applied geography although it also draws heavily upon the arts, the sciences and lessons of history. Some of the issues facing planning are considered briefly under the headings of rural exodus, urban exodus and Smart Growth.
Regional science
In the 1950s the regional science movement arose, led by Walter Isard to provide a more quantitative and analytical base to geographical questions, in contrast to the more qualitative tendencies of traditional geography programs. Regional Science comprises the body of knowledge in which the spatial dimension plays a fundamental role, such as regional economics, resource management, location theory, urban and regional planning, transport and communication, human geography, population distribution, landscape ecology, and environmental quality.
Reference

See also

- List of geography topics
- Geographical terms
- List of countries
- Geography reference tables
- Map
- Geographical renaming
- Geographic magazines
- National Geographic Society (United States)
- National Geographic Bee (United States)
- Point of Beginning
- Royal Geographical Society (United Kingdom)
External links

- [http://www.confluence.org/ Confluence.org - A work in progress, involving travelling to every point on the globe where the lines of longitude and latitude intersect and taking a photograph in each direction.]
- [http://www.aag.org/ Association of American Geographers]
- [http://www.gisuser.com/ GISuser.com, information-rich portal about GIS]
- [http://www.populationdata.net/ PopulationData.net]
- [http://www.freemaps.de/ Free Maps Germany]
- [http://www.ericdigests.org/1996-4/high.htm Using Literature To Teach Geography in High Schools. ERIC Digest.]
- [http://ericdigests.org/1992-5/geography.htm Teaching Geography at School and Home. ERIC Digest.]
- [http://ericdigests.org/1996-1/geography.htm The National Geography Content Standards. ERIC Digest.]
- [http://www.geo-guide.de Geo-Guide] extensive list of academic resources on geography and earth science
- [http://www.geopium.org Geopium: Geopolitics of Illicit Drugs in Asia]
- [http://www.nationalgeographic.com/ National Geographic Online]
- [http://www.rgs.org Royal Geographical Society]
- [http://www.rcgs.org Royal Canadian Geographical Society]
- [http://www.canadiangeographic.ca Canadian Geographic]
- [http://hypergeo.free.fr Hypergeo : Geographical Encyclopedia]
- [http://www.rare-maps.com/links.cfm Antique and Rare Maps - Art Source International] - Links to rare and antique maps and to cartography resources.
- [http://www.mapinfo.com/ MapInfo GIS Software]
- Category:School subjects als:Geografie ko:지리학 ms:Geografi ja:地理学 simple:Geography th:ภูมิศาสตร์

Landform

A landform comprises a geomorphological unit. Landforms are categorised by characteristics such as elevation, slope, orientation, stratification, rock exposure, and soil type. Landforms by name include berms, mounds, hills, cliffs, valleys, and so forth. Oceans and continents exemplify highest-order landforms. A number of factors, ranging from plate tectonics to erosion and deposition can generate and affect landforms. Biological factors can also influence landforms -- see for example the role of plants in the development of dune systems and salt marshes, and the work of corals and algae in the formation of coral reefs. coral reefs

List of landforms

- alas
- continent
- limestone pavement
- plain and plateau
- rock formations

Erosion landforms

Landforms produced by erosion and weathering usually occur in coastal or fluvial environments, and many appear above under those headings. Some other erosion landforms that do not fall into the above categories include:
- canyon
- cave
- limestone pavement
- tea table
- Deposition landform -- landforms produced by deposition of load or sediment (usually coastal or fluvial).
- Eolian landform - landforms produced by wind weathering.

External links

- [http://www.deh.gov.au/settlements/industry/minerals/booklets/landform/ Landform Design] Category:Geomorphology ja:地形

Elevation

:For other senses of this word, see elevation (disambiguation).

Basic Definition

In geography, the elevation of a geographic location is its height above mean sea level (or some other fixed point). Elevation is mainly used when referring to points on the Earth itself, while altitude is used for points in the air, such as an aircraft.

Determining Elevation

If you are reading a map from home, it is possible you may need to determine the elevation of some place. The main sort of map to use for this purpose is a topographical map. Learning to read a topographic map is relatively easy although assistance may be required for beginners. Image:HaleakalaMap.jpg Example of a topographical map. Haleakala, Hawaii. If you are somewhere and want to find its elevation, you may also survey it. Questions often arise about where to measure elevation from. The elevation of a mountain usually refers to its summit. The elevation of a hill also refers to the summit. A valley's elevation is usually taken from the lowest point but is often taken all over the valley.

Links

- Altitude
- Topographical map
- [http://www.usgs.gov/ US Geographical Survey]
- [http://www.gsi.go.jp/ENGLISH/ Geographical Survey Institute]
- [http://www.thefreedictionary.com/elevation The Free Dictionary, Elevation]
- Category:Physical geography Category:Length

Slope

In mathematics, the slope or the gradient of a straight line (within a Cartesian coordinate system) is a measure for the "steepness" of the line relative to the horizontal axis. With an understanding of algebra and geometry, one can calculate the slope of a straight line; with calculus, one can calculate the slope of the tangent to a curve at a point. The concept of slope, and much of this article, applies directly to grades or gradients in geography and civil engineering.

Definition of slope

The slope of a line in the plane containing the x and y axes is generally represented by the letter m, and is defined as the change in the y coordinate divided by the corresponding change in the x coordinate, between two distinct points on the line. This is described by the following equation: :

m = \frac

(The delta symbol, "Δ", is commonly used in mathematics to mean "difference" or "change".) Given two points (x₁, y₁) and (x₂, y₂), the change in x from one to the other is x₂ - x₁, while the change in y is y₂ - y₁. Substituting both quantities into the above equation obtains the following: :

m = \frac

Since the y-axis is vertical and the x-axis is horizontal by convention, the above equation is often memorized as "rise over run", where Δy is the "rise" and Δx is the "run". Therefore, by convention, m is equal to the change in y, the vertical coordinate, divided by the change in x, the horizontal coordinate; that is, m is the ratio of the changes. This concept is fundamental to algebra, analytic geometry, trigonometry, and calculus. Note that the points chosen and the order in which they are used is irrelevant; the same line will always have the same slope. Other curves have "accelerating" slopes and one can use calculus to determine such slopes.

Example 1

Suppose a line runs through two points: P(13,8) and Q(1,2). By dividing the difference in y-coordinates by the difference in x-coordinates, one can obtain the slope of the line: :

m = \frac = \frac = \frac = \frac = \frac

The slope is 1/2 = 0.5.

Example 2

If a line runs through the points (4, 15) and (3, 21) then: :

m = \frac = \frac = -6

Geometry

The larger the absolute value of a slope, the steeper the line. A horizontal line has slope 0, a 45° rising line has a slope of +1, and a 45° falling line has a slope of -1. The slope of a vertical line is not defined (it does not make sense to define it as +∞, because it might just as well be defined as -∞). The angle θ a line makes with the positive x axis is closely related to the slope m via the tangent function: :

m = \tan\,\theta

and :

\theta = \arctan\,m

(see trigonometry). Two lines are parallel if and only if their slopes are equal or if they both are vertical and therefore undefined; they are perpendicular (i.e. they form a right angle) if and only if the product of their slopes is -1 or one has a slope of 0 and the other is vertical and undefined.

Slope of a road, etc.

perpendicular There are two common ways to describe how steep a road is. One is by the angle in degrees, and the other is by the slope in a percentage. See also mountain railway. The formula for converting a slope in percentage to degrees is: :

\theta = \arctan\frac.

Algebra

If y is a linear function of x, then the coefficient of x is the slope of the line created by plotting the function. Therefore, if the equation of the line is given in the form :

y = mx + b \,

then m is the slope. This form of a line's equation is called the slope-intercept form, because b can be interpreted as the y-intercept of the line, the y-coordinate where the line intersects the y-axis. If the slope m of a line and a point (x₀, y₀) on the line are both known, then the equation of the line can be found using the point-slope formula: :

y - y_0 = m(x - x_0) \,

For example, consider a line running through the points (2, 8) and (3, 20). This line has a slope, m, of (20 - 8) / (3 - 2) = 12. One can then write the line's equation, in point-slope form: y - 8 = 12(x - 2) = 12x - 24; or: y = 12x - 16. The slope of a linear equation in the general form: :

Ax + By + C = 0 \,

is given by the formula: −A/B.

Calculus

The concept of a slope is central to differential calculus. For non-linear functions, the rate of change varies along the curve. The derivative of the function at a point is the slope of the line tangent to the curve at the point, and is thus equal to the rate of change of the function at that point.

Why calculus is necessary

tangent If we let Δx and Δy be the distances (along the x and y axes, respectively) between two points on a curve, then the slope given by the above definition, :

m = \frac

, is the slope of a secant line to a curve. For a line, the secant between any two points is identical to the line itself; however, this is not the case for any other type of curve. For example, the slope of the secant intersecting y = x² at (0,0) and (3,9) is m = (9 - 0) / (3 - 0) = 3 (which happens to be the slope of the tangent at, and only at, x = 1.5). However, by moving the points used in the above formula closer together so that Δy and Δx decrease, the secant line more closely approximates a tangent line to the curve. It follows that the secant line is identical to the tangent line when Δy and Δx equal zero; however, this results in a slope of 0/0, which is an indeterminate form (see also division by zero). The concept of a limit is necessary to calculate this slope; the slope is the limit of Δy / Δx as Δy and Δx approach zero. However, Δx and Δy are interrelated such that it is sufficient to take the limit where only Δx approaches zero. This limit is the derivative of y with respect to x. It may be written (in calculus notation) as dy/dx.

Map

] A map is a simplified depiction of a space, a navigational aid which highlights relations between objects within that space. Most usually a map is a two-dimensional, geometrically accurate representation of a three-dimensional space. The science and art of map-making is cartography.

Introduction

Map-making dates back to the Stone Age and appears to predate written language by several millennia. One of the oldest surviving maps is painted on a wall of the Catal Huyuk settlement in south-central Anatolia (now Turkey); it dates from about 6200 BC. Harvey 2000, p. 142]. While we tend to think of maps today as products of a rationalistic, scientific world-view, maps also have a mythic quality. Pre-modern maps, and mapping traditions outside the Western tradition, often merge geography with non-scientific cosmography, showing the relationship of the viewer to the universe. Medieval "T-O" maps, for example, show Jerusalem at the centre of the world, and in some cases related the "body" of the Earth to the body of Christ. By contrast, navigational (or "Portolan") charts of the Mediterranean from the same period are remarkably accurate. Even today, maps can be powerful rhetorical tools beyond their purely practical value, and this has been the source of much fruitful map criticism over the last twenty years, notably in the works of J.B. Harley, Mark Monmonier, and Denis Wood. Because maps are abstract representations of the world, they are not neutral documents and must be carefully interpreted. It is, of course, this abstraction that makes them useful. Lewis Carroll made this point humorously in Sylvie and Bruno with his mention of a fictional map that had "the scale of a mile to the mile". A character notes some practical difficulties with this map and states that "we now use the country itself, as its own map, and I assure you it does nearly as well". This conceit is elaborated in a one-paragraph story by Jorge Luis Borges and Adolfo Bioy Casares, generally known in English as "On Exactitude in Science". Road maps are perhaps the most widely used maps today, and form a subset of navigational maps, which also include aeronautical and nautical charts, railroad network maps, and hiking and bicycling maps. Community maps, including [http://GreenMap.org GreenMaps], are growing in importance. In terms of quantity, the largest number of drawn map sheets is probably made up by local surveys, carried out by municipalities, utilities, tax assessors, emergency services providers, and other local agencies. Many national surveying projects have been carried out by the military, such as the British Ordnance Survey (now a civilian government agency internationally renowned for its comprehensively detailed work).

Orientation of maps

Ordnance Survey, England. A classic "T-O" map with Jerusalem at centre, east toward the top, Europe the bottom left and Africa on the right.]] Conventionally, on most geometrically accurate maps text is upright when the map is oriented with the north up, hence north is identified with the top of a sheet. Maps that don't put north at the top: #Polar maps #Dymaxion maps # Some rectangular maps produced in Australia show the south pole at the top. To someone used to seeing the map the other way around, this map may appear to be "upside down". These are primarily intended as novelty and tourist maps. # Other modern maps put south on top, generally either out of a sense of playful confusion or to make a political statement about the North-South divide. # Old maps of Edo show the Japanese imperial palace as the "top," but also at the centre, of the map. Labels on the map are oriented in such a way that you cannot read them properly unless you put the imperial palace above your head. # Medieval European T and O maps such as the Hereford Mappa Mundi were centred on Jerusalem, with East at the top. If a person is located at an identifiable point within the area of such a map, then the map can be oriented in such a way that every point on the map lies in the same direction as the corresponding point in reality. The practice of navigating in this way is orienteering. For a vertically positioned map representing a horizontal area true orientation is not possible, of course, but it is sometimes approximated by putting the forward direction up. Occasionally a map is on a ceiling, correctly showing directions; in that case, looking up we have in clockwise direction forward, left, backward, and right. If the map is prepared on a table, to be attached to the ceiling, then on the table it is a mirror image of a normal map.

Scale and accuracy

Many but not all maps are drawn to a scale, allowing the reader to infer the actual sizes of, and distances between, depicted objects. A larger scale shows more detail, thus requiring a larger map to show the same area. For example, maps designed for the hiker are often scaled at the ratio 1:24,000, meaning that 1 of any unit of measurement on the map corresponds to 24,000 of that same unit in reality; while maps designed for the motorist are often scaled at 1:250,000. Maps which use some quality other than physical area to determine relative size are called cartograms. A famous example of a map without scale is the London Underground map, which best fulfils its purpose by being less physically accurate and more visually communicative to the hurried glance of the commuter. This is not a cartogram (since there is no consistent measure of distance) but a topological map that also depicts approximate bearings. The simple maps shown on some directional road signs are further examples of this kind. In fact, most commercial navigational maps, such as road maps and town plans, sacrifice an amount of accuracy in scale to deliver a greater visual usefulness to its user, for example by exaggerating the width of roads. With the end-user similarly in mind, cartographers will censor the content of the space depicted by a map in order provide a useful tool to that user. For example, a road map may or may not show railroads, and if it does, it may show them less clearly than highways.

World maps and projections

highways Maps of the world or large areas are often either 'political' or 'physical'. The most important purpose of the political map is to show territorial borders; the purpose of the physical is to show features of geography such as mountains, soil type or land use. Geological maps show not only the physical surface, but characteristics of the underlying rock, fault lines, and subsurface structures. Maps that depict the surface of the Earth also use a projection, a way of translating the three-dimensional real surface of the geoid to a two-dimensional picture. Perhaps the best-known world-map projection is the Mercator Projection, originally designed as a form of nautical chart. Airplane pilots use aeronautical charts based on a Lambert conformal conic projection, in which a cone is laid over the section of the earth to be mapped. The cone intersects the sphere (the earth) at one or two parallels which are chosen as standard lines. This allows the pilots to plot a great-circle route approximation on a flat, two-dimensional chart.

Electronic maps

Lambert conformal conic projection.]] Lambert conformal conic projection service called http://www.metrokc.gov/gis/mapportal/mapsets.htm I.map Map Sets]] From the last quarter of the 20th century, the indispensable tool of the cartographer has been the computer. Much of cartography, especially at the data-gathering survey level, has been subsumed by Geographic Information Systems (GIS). Even when GIS is not involved, most cartographers now use a variety of computer graphics programs to generate new maps. Interactive, computerised maps are commercially available, allowing users to zoom in or zoom out (respectively meaning to increase or decrease the scale), sometimes by replacing one map with another of different scale, centred where possible on the same point. In-car satellite navigation systems are computerised maps with route-planning and advice facilities which monitor by satellite the position of the user. From the computer scientist's standpoint, zooming in entails one or a combination of: #replacing the map by a more detailed one #enlarging the same map without enlarging the pixels, hence show more detail #enlarging the same map with the pixels enlarged (replaced by rectangles of pixels); no additional detail is shown, but, depending on the quality of one's vision, possibly more detail can be seen; if a computer display does not show adjacent pixels really separate, but overlapping instead (this does not apply for an LCD, but may apply for a cathode ray tube), then replacing a pixel by a rectangle of pixels does show more detail. A variation of this method is that interpolation is performed. For example:
- Typically (2) applies to a Portable Document Format (PDF) file. The increase in detail is, of course, limited to the information contained in the file: enlargement of a curve may eventually result in a series of standard geometric figures such as straight lines or arcs of circles.
- (2) may apply to text and (3) to the outline of a map feature such as a forest or building.
- (1) may apply to the text (displaying labels for more features), while (2) applies to the rest of the image. Text is not necessarily enlarged when zooming in. Similarly, a road represented by a double line may or may not become wider when one zooms in.
- The map may also have layers which are partly raster graphics and partly vector graphics. For a single raster graphics image (2) applies until the pixels in the image file correspond to the pixels of the display, thereafter (3) applies. The word "map" has also been used to describe places within video games, such as SOCOM II: U.S. Navy SEALs and Counter-Strike, that players choose to compete on, as a synonym for level. See also Webpage (Graphics), PDF (Layers), Mapquest, or Yahoo! Maps.

References

- David Buisseret, ed., Monarchs, Ministers and Maps: The Emergence of Cartography as a Tool of Government in Early Modern Europe. Chicago: University of Chicago Press, 1992, [ISBN 0226079872]
- Miles Harvey, The Island of Lost Maps: A True Story of Cartographic Crime. New York : Random House, 2000. [ISBN 0767908260, cited above; also ISBN 0375501517]
- Mark Monmonier, How to Lie with Maps, [ISBN 0226534219]
- O'Connor, J.J. and E.F. Robertson, [http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Cartography.html The History of Cartography]. Scotland : St. Andrews University, 2002. http://www-gap.dcs.st-and.ac.uk/~history/HistTopics/Cartography.html

External links

- Microsoft: MSN [http://maps.msn.com/]
- world atlas (the whole world on the same scale: 4 km = 49 pixels, 82 m / pixel)
- North America (Canada, US, Mexico), US to street level, Mexico only some parts to street level (for the other parts street level scale is available, but it shows blank maps with e.g. only one dot to represent a village)
- Western Europe to street level, see [http://maps.msn.com/(lhseei35lfegqtv3zp4gqg45)/map.aspx?&lats1=50&lons1=17&alts1=10000®n1=1 map of area covered]
- Australia
- Brazil
- [http://www.ab-map.com/ US Map]: ABMap - Interactive World Map and detailed united states street map
- [http://geographersblog.blogspot.com/ Antique Maps Yellow] News and Commentary about Antique Maps (Blog)
- [http://fax.libs.uga.edu/hmaps/ Historical Maps from the Hargrett Library Collection] (University of Georgia) --browse over 1000 maps from as early as 1544-- DjVu format; requires free plugin or JAVA
- [http://texashistory.unt.edu/browse/subject/Texas_Landscape_and_Nature/Geography_and_Maps/ Historical Maps from the Portal to Texas History]
- atlases with maps by country:
- [http://www.populationdata.net/cartes/cartes.html PopulationData.net]
- [http://www.cia.gov/cia/publications/factbook/] The World Factbook
- the same maps but with a faster, cleaner directory: [http://www.lib.utexas.edu/maps/cia04.html]
- [http://go.hrw.com/atlas/norm_htm/ Holt, Rinehart and Winston]
- [http://www.infoplease.com/atlas/ Infoplease]
- [http://www.lib.utexas.edu/maps UT scanned collection] - University of Texas at Austin (also at [http://us.aminet.net/pix/map/] and [http://wuarchive.wustl.edu/aminet/pix/map ]; [http://images.google.com/images?q=aminet%20map thumbnails at Google])
- [http://www.lib.utexas.edu/maps/map_sites/country_sites.html list of links including those to external sites]
- [http://www.aquarius.geomar.de/ Online Map Creation]: Webinterface to GMT mapping package
- new version: [http://www.planiglobe.com/omc_set.html Planiglobe]
- [http://www.mapzones.com MapZones] Map of all countries
- [http://www.multimap.com/ Multimap world atlas]: on UK, US, Canada, Australia and Western Europe more detailed than the rest of the world; the list of scales to select from is location-dependent - also provides geographic coordinates of a location selected from a map.
- MapQuest [http://www.mapquest.com/maps]: on US, Canada and Western Europe more detailed than the rest of the world - the list of scales to select from is not location-dependent: for part of the world several zoom level links lead to an image with just the message "No Data Available".
- [http://www.welt-atlas.de/worldatlas/ Atlas of the World] A world atlas with hundreds of very detailed and elaborate maps from every part of the world
- [http://maps.yahoo.com Yahoo Maps]: on US, Canada, Germany, France, Spain, Italy
- [http://de.maps.yahoo.com/ Yahoo Germany]: on France, UK, Germany, Italy, Spain, Portugal, Austria, Switzerland, Benelux
- [http://www.landkarte-online.net/ Maps of the World] (ger.)
- [http://krak.dk/ krak.dk]: Interactive map of Denmark
- [http://www.routenplaner24.de/ Routenplaner24] Street Maps and Route Planner in Germany
- [http://www.mapsouthpacific.com/ Map South Pacific]: on Polynesia, Melanesia, Micronesia
- [http://www.freeworldmaps.net/ World and Continent Maps]
- [http://www.streetmaps.de/ Street Maps in Switzerland, Austria and Germany]
- [http://plasma.nationalgeographic.com/mapmachine/ MapMachine] (National Geographic/ESRI)
- [http://www.nationalatlas.gov/ National Atlas of the United States]
- [http://nationalatlas.gov/reference.html US state maps]
- [http://www.citoplan.nl/citoplan/img/legenda_groot.gif Example of legend (Cito-Plan city maps)]
- http://www.geocities.com/marcoschmidt.geo/geo-data.html
- [http://nationalmap.usgs.gov/ USGS National Map]
- [http://www.web-routenplaner.de/ Free Maps and Route Planner on Europe]
- [http://www.outdoormountain.com/shopping/maps.php Maps of OutdoorMountain]
- [http://www.sunysb.edu/libmap/libcats.htm Online Map Catalogs in North America and Europe] Lists some good places to search for online maps
- [http://oddens.geog.uu.nl The fascinating world of maps and mapping] Lists all kinds of maps
- [http://www.maphistory.info/collections.html Map collections] Intorductory page to help navigate the online map resources
- [http://www.uidaho.edu/special-collections/Other.Repositories.html A listing of over 5000 websites] describing holdings of manuscripts, archives, rare books, historical photographs, and other primary sources for the research scholar
- [http://www.guiageo.com Brazilian and World Maps] Vector PDF maps of Brazilian states
- [http://www.centamap.com/cent/index.htm Hong Kong Maps] CentaMap
- [http://www.freeroute.de/ FreeRoute Germany]
- [http://www.cgrer.uiowa.edu/servers/servers_references.html#atlases Links to on-line atlases]
- [http://www.links4maps.com Link Directory for Maps] Link directory of map libraries and societies, antique maps and world, regional, travel, historical and other map resources.
- [http://www.matton.com/maps Royalty Free Maps] Royalty Free Vector and Bitmap Maps, available in Illustrator format.
- [http://www.mcwetboy.net/maproom/ Map Room] - a weblog about maps
- [http://www.rare-maps.com/links.cfm Antique and Rare Maps - Art Source International] - Links to rare and antique maps and to cartography resources.
- Google
- [http://earth.google.com Google Earth]: Interactive map of the world
- [http://maps.google.com Google Maps] Google's map system, similar to Mapquest.
- [http://www.flourish.org/upsidedownmap/ The Upsidedown Map Page] Pictures and info about maps which are oriented without North at the top
- [http://en.wikipedia.org/wiki/Wikipedia:Maps Wikipedia:Maps], use of maps on Wikipedia Note that map services with various zoom levels sometimes show a new map item, such as a new bridge, only on a smaller-scale map and not on an available larger scale map, because the latter is not as often updated, see e.g. the Tuas Second Link on [http://www.multimap.com/p/browse.cgi?scale=100000&lon=103.85&lat=1.3&scale=2000000], and larger scales which do not show it. Category:Cartography ja:地図

Shade

Shade is the blocking of sunlight (in particular direct sunshine) by any object, and also the shadow created by that object. It may refer to blocking of sunlight by a roof, a tree, an umbrella, a window shade or blind, curtains, or other objects. Shade is an important issue in temperate and tropical zones for providing cooling and shelter from the sun. Providing certain configurations of shading is an important passive solar technique. This may be done with overhangs, with shade trees, or with vines. Shading using non-living materials blocks the sun, but also results in sunlight being absorbed and re-radiated as heat, or in sunlight being reflected as glare. Green plants, on the other hand, not only absorb a significant portion of the sunlight to invest as energy in photosynthesis to produce sugar, but also actively transpire, producing an additional cooling effect. ---- vines Shading is a process used in drawing for depicting levels of darkness on paper by applying more pressure with a drawing implement for darker areas, and less pressure for lighter areas. There are various techniques of shading including cross hatching where perpendicular lines of varying closeness are drawn in a grid pattern to shade an area. The closer the lines are together, the darker the area appears and vice versa. The term has been recently generalized to mean that shaders are applied. Light patterns, such as objects having light areas and shaded areas, help when creating the illusion of depth on paper and on computer screens. See also 3D computer graphics / Reflection and shading models. ---- A Shade in the esoteric or spiritual sense can be one of many things. A spiritual or emotional imprint left on a person, place or thing. A "presence" that which is seen out of the corner of the eye or known (sometimes physically felt) only under conditions and times. They can come in many forms, anything from a deceased (or living for that matter) person's or animal's imprint left on something or someone, to something invoked into the "possession" of an object and even sometimes a person. ---- In marketing, price shading is a variant of variable pricing in which sales people are given the authority to vary the price by a certain amount or percentage. Category:Drawing

Surface

:For other senses of this word, see surface (disambiguation). surface (disambiguation) In mathematics (topology), a surface is a two-dimensional manifold. Examples arise in three-dimensional space as the boundaries of three-dimensional solid objects. The surface of a fluid object, such as a rain drop or soap bubble, is an idealisation. To speak of the surface of a snowflake, which has a great deal of fine structure, is to go beyond the simple mathematical definition. For the nature of real surfaces see surface tension, surface chemistry, surface energy, roughness.

Definition

In what follows, all surfaces are considered to be second-countable 2-dimensional manifolds. More precisely: a topological surface (with boundary) is a Hausdorff space in which every point has an open neighbourhood homeomorphic to either an open subset of E² (Euclidean 2-space) or an open subset of the closed half of E². The set of points which have an open neighbourhood homeomorphic to Eⁿ is called the interior of the manifold; it is always non-empty. The complement of the interior, is called the boundary; it is a (1)-manifold, or union of closed curves. A surface with empty boundary is said to be closed if it is compact, and open if it is not compact.

Classification of closed surfaces

There is a complete classification of closed (i.e compact without boundary) connected, surfaces up to homeomorphism. Any such surface falls into one of two infinite collections:
- Spheres with g handles attached (called g-fold tori). These are orientable surfaces with Euler characteristic 2-2g, also called surfaces of genus g.
- Spheres with k projective planes attached. These are non-orientable surfaces with Euler characteristic 2-k. Therefore Euler characteristic and orientability describe a compact surfaces up to homeomorphism (and if surfaces are smooth then up to diffeomorphism).

Compact surfaces

Compact surfaces with boundary are just these with one or more removed open disks whose closures are disjoint.

Embeddings in R³

A compact surface can be embedded in R³ if it is orientable or if it has nonempty boundary. It is a consequence of the Whitney embedding theorem that any surface can be embedded in R⁴.

Differential geometry

A simple review of the embedding of a surface in n dimensions, and a computation of the area of such a surface, is provided in the article volume form. Metric properties of Riemann surfaces are briefly reviewed in the article Poincaré metric.

Some models

To make some models of various surfaces, attach the sides of these squares (A with A, B with B) so that the directions of the arrows match: Image:SphereAsSquare.png|sphere Image:ProjectivePlaneAsSquare.png|real projective plane Image:KleinBottleAsSquare.png|Klein bottle Image:TorusAsSquare.png|torus

Fundamental polygon

Each closed surface can be constructed from an even sided oriented polygon, called a fundamental polygon by pairwise identification of its edges. This construction can be represented as a string of length 2n of n distinct symbols where each symbol appears twice with exponent either +1 or -1. The exponent -1 signifies that the corresponding edge has the orientation opposing the one of the fundamental polygon. The above models can be described as follows:
- sphere:

A A^

- projective plane:

A A

- Klein bottle:

A B A^ B

- torus:

A B A^ B^

(See the main article fundamental polygon for details.)

Connected sum of surfaces

Given two surfaces M and M', their connected sum M # M' is obtained by removing a disk in each of them and gluing them along the newly formed boundary components. We use the following notation.
- sphere: S
- torus: T
- Klein bottle: K
- Projective plane: P Facts:
- S # S = S
- S # M = M
- P # P = K
- P # K = P # T We use a shorthand natation: nM = M # M # ... # M (n-times) with 0M = S. Closed surfaces are classified as follows:
- gT (g-fold torus): orientable surface of genus g, for

g \ge 0

.
- gP (g-fold projective plane): non-orientable surface of genus g, for

g \ge 1

Algebraic surface

This notion of a surface is distinct from the notion of an algebraic surface. A non-singular complex projective algebraic curve is a smooth surface. Algebraic surfaces over the complex number field have dimension 4 when considered as a real manifold.

External links

- [http://xahlee.org/surface/gallery.html Math Surfaces Gallery, with 60 ~surfaces and Java Applet for live rotation viewing] Category:Surfaces Category:Geometric topology ja:表面

Greek language

Greek (Greek Ελληνικά, IPA – "Hellenic") is an Indo-European language with a documented history of 3,500 years. Today, it is spoken by 15 million people in Greece, Cyprus, the former Yugoslavia, particularly The Former Yugoslav Republic of Macedonia, Bulgaria, Albania and Turkey. There are also many Greek emigrant communities around the world, such as those in Melbourne, Australia which is the third-largest Greek-populated city in the world, after Athens and Thessaloniki. Greek has been written in the Greek alphabet, the first true alphabet, since the 9th century B.C. and before that, in Linear B and the Cypriot syllabaries. Greek literature has a long and rich tradition.

History

This article does not cover the reconstructed history of Greek prior to the use of writing. For more information, see main article on Proto-Greek language. Greek has been spoken in the Balkan Peninsula since the 2nd millennium BC. The earliest evidence of this is found in the Linear B tablets dating from 1500 BC. The later Greek alphabet (q.v.) is unrelated to Linear B, and was derived from the Phoenician alphabet (abjad); with minor modifications, it is still used today. Greek is conventionally divided into the following periods:
- Mycenean Greek: the language of the Mycenean civilisation. It is recorded in the Linear B script on tablets dating from the 16th century BC onwards.
- Classical Greek (also known as Ancient Greek): In its various dialects was the language of the Archaic and Classical periods of Greek civilisation. It was widely known throughout the Roman empire. Classical Greek fell into disuse in western Europe in the Middle Ages, but remained known in the Byzantine world, and was reintroduced to the rest of Europe with the Fall of Constantinople and Greek migration to Italy.
- Hellenistic Greek (also known as Koine Greek): The fusion of various ancient Greek dialects with Attic (the dialect of Athens) resulted in the creation of the first common Greek dialect, which gradually turned into one of the world's first international languages. Koine Greek can be initially traced within the armies and conquered territories of Alexander the Great, but after the Hellenistic colonisation of the known world, it was spoken from Egypt to the fringes of India. After the Roman conquest of Greece, an unofficial diglossy of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. Through Koine Greek it is also traced the origin of Christianity, as the Apostles used it to preach in Greece and the Greek-speaking world. It is also known as the Alexandrian dialect, Post-Classical Greek or even New Testament Greek (after its most famous work of literature).
- Medieval Greek: The continuation of Hellenistic Greek during medieval Greek history as the official and vernacular (if not the literary nor the ecclesiastic) language of the Byzantine Empire, and continued to be used until, and after the fall of that Empire in the 15th century. Also known as Byzantine Greek.
- Modern Greek: Stemming independently from Koine Greek, Modern Greek usages can be traced in the late Byzantine period (as early as 11th century). Two main forms of the language have been in use since the end of the medieval Greek period: Dhimotikí (Δημοτική), the Demotic (vernacular) language, and Katharévousa (Καθαρεύουσα), an imitation of classical Greek, which was used for literary, juridic, and scientific purposes during the 19th and early 20th centuries. Demotic Greek is now the official language of the modern Greek state, and the most widely spoken by Greeks today. It has been claimed that an "educated" speaker of the modern language can understand an ancient text, but this is surely as much a function of education as of the similarity of the languages. Still, Koinē , the version of Greek used to write the New Testament and the Septuagint, is relatively easy to understand for modern speakers. Greek words have been widely borrowed into the European languages: astronomy, democracy, philosophy, thespian, etc. Moreover, Greek words and word elements continue to be productive as a basis for coinages: anthropology, photography, isomer, biomechanics etc. and form, with Latin words, the foundation of international scientific and technical vocabulary. See English words of Greek origin, and List of Greek words with English derivatives.

Classification

Greek is an independent branch of the Indo-European language family. The ancient languages which were probably most closely related to it, Ancient Macedonian language (which may be regarded as a dialect of Greek) and Phrygian, are not well enough documented to permit detailed comparison. Among living languages, Armenian seems to be the most closely related to it.

Geographic distribution

Modern Greek is spoken by about 15 million people mainly in Greece and Cyprus. There are also Greek-speaking populations in Georgia, Ukraine, Egypt, Turkey, Albania, Former Yugoslav Republic of Macedonia and Southern Italy. The language is spoken also in many other countries where Greeks have settled, including Armenia, Australia, Austria, Belgium, Bulgaria, Canada, Denmark, France, Germany, Netherlands, Sweden, United Kingdom, and the United States.

Official status

Greek is the official language of Greece where it is spoken by about 99.5% of the population. It is also, alongside Turkish, the official language of Cyprus. Due to the membership of Greece and Cyprus, Greek is one of the 20 official languages of the European Union.

Phonology

This section generally describes the post-Classic phonology of the Greek language. :All phonetic transcriptions in this section use the International Phonetic Alphabet

Vowel sounds

Greek has 5 vowel sounds, all phonemic:

18th century

As a means of recording the passage of time, the 18th century refers to the century that lasted from 1701 through 1800 in the Gregorian calendar. European history scholars will sometimes specifically refer to the 18th century as 1715-1789, denoting the period of time between the death of Louis XIV of France and the start of the French Revolution.

Events

- 1701-14: War of the Spanish Succession
- 1703: Saint Petersburg founded by Peter the Great. Russian capital until 1918.
- 1707: Act of Union passed merging the Scottish and the English Parliaments, thus establishing The Kingdom of Great Britain.
- 1707: After Aurangzeb's death, the Mughal Empire enters a long decline.
- 1715: Louis XIV dies
- 1718: City of New Orleans founded by the French in North America
- 1720: The South Sea Bubble
- 1721: Robert Walpole becomes the first Prime Minister of Great Britain (de facto).
- 1721: Treaty of Nystad signed, ending the Great Northern War.
- 1722: Afghans conquer Iran, ending the Safavid dynasty.
- 1722: Kangxi Emperor of China dies.
- 1733-38: War of the Polish Succession
- 1735-99: The Qianlong Emperor of China oversees a huge expansion in territory.
- 1736: Nadir Shah assumes title of Shah of Persia and founds the Afsharid dynasty. Rules until his death in 1747.
- 1739: Nadir Shah defeats the Mughals and sacks Delhi.
- 1740: Frederick the Great crowned King of Prussia.
- 1740-48: War of the Austrian Succession
- 1741: Russians begin settling the Aleutian Islands.
- 1747: Ahmad Shah founds the Durrani Empire in modern day Afghanistan.
- 1750: peak of the Little Ice Age
- 1755: The Lisbon earthquake
- 1756-63: Seven Years' War fought among European powers in various theaters around the world.
- 1757: Battle of Plassey signals the beginning of British rule in India.
- 1760: George III becomes King of Britain.
- 1762-96: Reign of Catherine the Great of Russia.
- 1763-66: Pontiac's Rebellion in North America
- 1766-99: Anglo-Mysore Wars
- 1767: Burmese conquer the Ayutthaya kingdom.
- 1768: Gurkhas conquer Nepal.
- 1768-1774: Russo-Turkish War
- 1769: Spanish missionaries establish the first of 21 missions in California.
- 1772-95: The Partitions of Poland end the Polish-Lithuanian Commonwealth and erase Poland from the map for 123 years.
- 1775-82: First Anglo-Maratha War
- 1775-83: American Revolution
- 1779-1879: Cape Frontier Wars between British and Boer settlers and the Xhosas in South Africa
- 1785-95: Northwest Indian War between the United States and Native Americans
- 1787: Freed slaves from London found Freetown in present-day Sierra Leone.
- 1788: First European settlement established in Australia at Sydney.
- 1789: George Washington elected President of the United States. Serves until 1797.
- 1789-99: The French Revolution
- 1791-1804: The Haitian Revolution
- 1792-1815: The Great French War starts as the French Revolutionary Wars which lead into the Napoleonic Wars.
- 1792: New York Stock & Exchange Board founded.
- 1793: Upper Canada bans slavery.
- 1795: Pinckney's Treaty between the United States and Spain grants the Mississippi Territory to the US.
- 1796: British eject Dutch from Ceylon.
- 1796-1804: White Lotus Rebellion in China.
- 1797: Napoleon's invasion and partition of the Republic of Venice ends over 1,000 years of independence for the Serene Republic.
- 1798: Irish Rebellion against British Rule
- 1798-1800: Quasi-War between the United States and France.
- 1799: Napoleon stages a coup d'état and becomes dictator of France.
- 1799: Dutch East India Company is dissolved.

Significant people

- Ueda Akinari (Japanese writer)
- Queen Anne (British monarch)
- Marie Antoinette (French royalty and symbol of anti-Revolutionary ire)
- Benedict Arnold, considered a traitor by many people on both sides (United States and Britain) of the American Revolutionary War.
- Johann Sebastian Bach (composer)
- Pierre Beaumarchais (French writer)
- Jeremy Bentham (English jurist, philosopher, and legal and social reformer)
- Napoleon Bonaparte (general and first consul of France)
- François Boucher (French painter)
- Edmund Burke (British statesman and philosopher who supported the American Revolution)
- Robert Burns (Scottish poet)
- Catherine the Great (Russian Tsaritsa)
- James Cook (British navigator)
- Denis Diderot (French writer and philosopher)
- Leonhard Euler (mathematician)
- Jean-Honoré Fragonard (French painter)
- Benjamin Franklin (American revolutionary, inventor, printer, and diplomat)
- Frederick the Great (Prussian monarch)
- Thomas Gainsborough (painter)
- King George III (British monarch)
- Christoph Willibald Gluck (German composer)
- Johann Wolfgang von Goethe (German writer)
- Thomas Gray (British writer)
- George Frideric Handel (German composer)
- Alexander Hamilton (American revolutionary, lawyer, and statesman)
- Joseph Haydn (Austrian composer)
- William Hogarth (painter and engraver)
- David Hume (philosopher)
- Thomas Jefferson (American revolutionary, philosopher, and statesman)
- Samuel Johnson (British writer and literary critic)
- Immanuel Kant (philosopher)
- Wolfgang von Kempelen (Hungarian scientist, pioneer in experimental phonetics)
- John Law (Scottish economist)
- Louis XIV of France (monarch)
- Louis XV of France (monarch)
- Louis XVI of France (monarch)
- James Madison (American revolutionary, writer, and statesman)
- Maria Theresa of Austria (Holy Roman Empress, Queen of Hungary and Bohemia)
- Michikinikwa (Miami tribe chief and war leader)
- Wolfgang Amadeus Mozart (composer)
- Thomas Paine (British intellectual and philosopher who advocated for the American Revolution)
- Philip II, Duke of Orléans (Regent of France)
- Alexander Pope (British poet)
- Francis II Rákóczi (prince of Hungary and Transylvania, leader of the Hungarian freedom war)
- Jean-Philippe Rameau (French composer and music theorist)
- Sir Joshua Reynolds (painter)
- Maximilien Robespierre (French Revolutionary leader and dictator)
- Jean-Jacques Rousseau (French writer and philosopher)
- Friedrich Schiller (German writer)
- John Small, Sr (Hambledon cricketer; the first great batsman)
- Adam Smith (Scottish economist and philosopher)
- Laurence Sterne (British writer)
- Edward "Lumpy" Stevens (Surrey cricketer; the first great bowler)
- Jonathan Swift (Anglo-Irish satirist)
- Tecumseh (Revolutionary)
- Voltaire (French writer and philosopher)
- George Washington (American revolutionary general and first president)
- John Wesley (Founder of Methodism, Anglican clergyman, English reformer, scholar, theologian and writer) See Founding Fathers of the United States

Inventions, discoveries, introductions

List of 18th century inventions
- Industrial Revolution begins
- The Encyclopédie by the Encyclopedists
- The English Dictionary by Samuel Johnson
- Economics by Adam Smith
- Rosetta stone discovered by Napoleon's troops.
- Vitus Bering discovered Alaska.
- James Cook mapped the boundaries of the Pacific Ocean and discovered many Pacific Islands.
- Wahhabism by Muhammad ibn Abd al Wahhab

Decades and years

- Category:Centuries Category:Industrial Revolution Category:Romanticism ko:18세기 ja:18世紀 th:คริสต์ศตวรรษที่ 18

United States Geological Survey

United States Geological Survey
United States Geological Survey logo
Established:	March 3, 1879
Acting Director:	P. Patrick Leahy
Budget:	$938 million (FY2004)
Employees:	10,000 (2004)

The United States Geological Survey (USGS) is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology, geography, geology, and hydrology. The USGS is a fact-finding research organization with no regulatory responsibility. The USGS was founded by Clarence King in March 3, 1879 from disparate regional survey agencies. Since 1962, it has been involved in global, lunar and planetary exploration and mapping. Part of the United States Department of the Interior, it is the department's sole scientific agency. The USGS employs approximately 10,000 people and is headquartered in Reston, Virginia, with major offices in Denver, Colorado, and Menlo Park, California. The USGS is the primary civilian mapping agency in the United States, and is best known for its 1:24,000 scale, 7.5-minute quadrangle

Topography

See also

Geography

Structure of geography

Physical geography

Human geography

Socio-environmental geography

Cultural and political ecology

Risk-hazards research

Historical geography

History of geography

Geographic techniques

Related fields

Urban and regional planning

Regional science

Reference

See also

External links

Landform

See also

List of landforms

Slope landforms

Coastal and oceanic landforms

Fluvial landforms

Mountain and glacial landforms

Volcanic landforms

Erosion landforms

External links

Elevation

Basic Definition

Determining Elevation

Links

Slope

Definition of slope

Example 1

Example 2

Geometry

Slope of a road, etc.

Algebra

Calculus

Why calculus is necessary

See also

Map

Introduction

Orientation of maps

Scale and accuracy

World maps and projections

Electronic maps

References

See also

External links

Shade

Surface

Definition

Classification of closed surfaces

Compact surfaces

Embeddings in R3

Differential geometry

Some models

Fundamental polygon

Connected sum of surfaces

Algebraic surface

See also

External links

Greek language

History

Classification

Geographic distribution

Official status

Phonology

Vowel sounds

18th century

Events

Significant people

Inventions, discoveries, introductions

Decades and years

United States Geological Survey

Embeddings in R³