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map projections.ppt
- 1. Map Projections & Their Effects on Perceptions in the Study of World History
- 2. What is a map? • A generalized view of an area, usually some portion of Earth’s surface, as seen from above at a greatly reduced size • Any geographical image of the environment • A two-dimensional representation of the spatial distribution of selected phenomena
- 3. Why make a map? • To represent a larger area than we can see • To show a phenomenon or process we can’t see with our eyes • To present information concisely • To show spatial relationships
- 4. Represent a larger area
- 8. What should we think about when we read maps? What do cartographers think about? • How will the flat map represent a curved surface? (projection) • Maps are selective views of reality (simplification) • Size of the map relative to reality (scale) • What’s on the map (symbolization) • What size of unit will be measured by the map (aggregation) • What type of map is being used? (reference or thematic)
- 9. “Map Projection” • The Earth is a sphere – it is accurately represented in the form of a globe. • Globe is a limited tool • Projection – the scientific method of transferring locations on Earth’s surface to a flat map
- 10. Create your own projection · Think of the beach ball as Earth. · Identify and mark (with your sharpie) on the grapefruit the locations of the North Pole and South Pole. · Then locate the spot that is halfway between the two poles and use a marker to draw a line around the Earth at that point, which geographers refer to as the equator. · Draw a few lines of longitude on the map, including a “prime meridian” · Then draw shapes to represent the continents on Earth. · Use the scissors to cut the beach ball – attempt to make the new map as flat as possible - Next, try to create from the sphere (grapefruit) a map that is flat and readable. Reflection Question: Are you able to create an accurate 2-D map from the grapefruit peel? Explain the activity and what is different from the grapefruit map to the flat map?
- 11. Distortion • Earth on a flat piece of paper creates distortions. Four types of distortions can result: – The shape of an area can be distorted, so that it appears more elongated or squat than in reality – The distance between two points may become increased or decreased – The relative size of different areas may be altered, so that one area may appear larger than another on a map but is in reality smaller – The direction from one place to another can be distorted
- 12. Medieval European T-O Map. In medieval Europe one of the most common forms of rendering the earth was the mappae mundi of which more than a thousand have survived. The T-O map is one kind of mappae mundi. The T-O image reproduced here comes from the encyclopedia of knowledge produced by Isidore, Bishop of Seville, in 630 A.D., and was printed in Augsburg in 1472.
- 13. The Maya Cosmos. Adopted with modifications from Linda Schele and David Freidel, A Forest of Kings: The Untold Story of the Ancient Maya (N.Y.: William Morrow, 1990), p. 67, fig. 2:1. Drawing by Linda Schele, courtesy Foundation for the Advancement of Mesoamerican Studies, Inc. (permissions Nov. 7, 2002).
- 14. An ancient map that strongly suggests Chinese sailors were first to round the world.
- 16. The Mercator Projection • Direction is true everywhere on his map • Distorts size of areas
- 18. The Robinson Projection • Tries to correct for the Mercator Projection’s distortions by curving distorted areas inwards. • Attempts to balance all distortions by making errors in all four ways: – Shape – Size – Distance – Direction
- 20. The Peters Projection • Focuses on keeping land masses equal in area. Shapes are distorted.
- 21. The West Wing: Map Projections What does this clip reveal about the importance of map projections?
- 23. A modern modification of the Mercator projection is Miller's cylindrical projection that decreases the amount of distortion in the high latitudes while setting the earth's surface on a rectangular grid.
- 24. Miller World Map Centered Along 90th West Meridian . It projects an American perspective on the world.
- 26. Rearranged Map: Brazil Perspective,
- 27. Seventeenth Century Atlantic Basin. Lines indicate direction of movement of goods from Europe and Africa to the Americas and from the Americas to Asia. Europe was the source of financial and commercial activity, while Africa was primarily important for the slave trade—so that the main cultural impacts were those of Europe upon Africa, and Africa upon America. This was the transoceanic arena in which an Atlantic World emerged in the Age of Empire, and the geographical stage for cross-cultural encounters, Spanish treasure fleets, a transatlantic slave trade, and the movement of European peoples. Adopted with permission from D.W. Meining, The Shaping of America: A Geographical Perspective on 500 Years of History. Volume 1, Atlantic America, 1492–1800 (Yale University Press, 1986), p. 56
- 29. North America appears to be more involved in the Pacific Basin than South America (its eastward location pulling it toward the Atlantic). Finally, this map reveals a major truth about the earth, and that is that the earth is mostly water not land, the Pacific Ocean amounting to 64,000,000 square miles (over twice the size of the Atlantic Ocean).
- 30. Miller World Map Centered on 180 Meridian: The Pacific Perspective. South is at top of map. After 1850, a Pacific perspective must be added. With the United States acquiring Alaska, the Aleutian Islands, and Hawaii (and taking possession of the Philippines), followed by Pearl Harbor and the Pacific theater of World War II, the strategic importance of the Pacific for the United States becomes obvious. With China emerging as a major power, the twenty-first century may become the Pacific century.
- 31. The Peters Projection Map from Two Perspectives: In 1974, as an effort to reduce the political bias of conventional maps, Arno Peters created the 'Peters Projection' of the world so that one square inch anywhere on the map represents an equal number of square miles of the earth's surface.
- 33. "Political" Map
- 34. The Myth of Continents
- 37. The Myth of Continents • The traditional notion of continents can be abandoned (or at least modified). The idea of a North American continent, separate from South America, encourages false dichotomies that do not reflect actual biological, geological, and cultural realities, and that overlooks many themes that parallel the history of both regions (from cowboy culture to urbanization). • By substituting a world regionalism scheme for the continental one, today's students will be using a regional classification that better fits the realities of ethnicity, culture, and history. This, then, would be the beginning of an attempt to look at the New Old World in a new way.
- 39. Which map projection does the College Board use in their WHAP materials?
Editor's Notes
- It seems more likely that the world and all its continents were discovered by a Chinese admiral named Zheng He, whose fleets roamed the oceans between 1405 and 1435. His exploits, which are well documented in Chinese historical records, were written about in a book which appeared in China around 1418 called "The Marvellous Visions of the Star Raft". One of Zheng He's fleet's adventures, blown off course to the east to the New World, provides a fascinating thread in Neil Stephenson's fabulous fiction, Cryptonomicon. It is a copy, made in 1763, of a map, dated 1418, which contains notes that substantially match the descriptions in the book . Each fleet would have at least one "Treasure ship", used by the commander of the fleet and his deputies (nine-masted, about 120 meters (400 ft) long and 50 m (160 ft) wide).
- The greatest "inventor" of sixteenth century Europe was map maker Gerhardus Mercator whose 1569 summary map, publicized by the learned Richard Hakluyt in his Principal Navigations, Voyages and Discoveries of the English Nation (London: 1589), liberated cartography from dependence on Ptolemy, and included a projection that allowed navigators to understand the coasts of the New World. These maps silently promoted a Eurocentric view that privileged the Western image. Generations of European and American students have been indoctrinated with the glories of nationalism and colonialism through this map.
- This projection was presented by Arthur H. Robinson in 1963, and is also called the Orthophanic projection, which means right appearing. Scale is true along the 38º parallels and is constant along any parallel or between any pair of parallels equidistant from the Equator. It is not free of distortion at any point, but distortion is very low within about 45º of the center and along the Equator. This projection is not equal-area, conformal, or equidistant; however, it is considered to look right for world maps, and hence is widely used by Rand McNally, the National Geographic Society, and others. This feature is achieved through the use of tabular coordinates rather than mathematical formulae for the graticules.
- If the map is cut to place the center along the Prime Meridian, the result is a Eurocentric map useful for many purposes but not the only way to view the world.
- Note how the three major countries of North America, the United States, Canada, and Mexico, face both the Atlantic and Pacific oceans, while in South America only Colombia has a two-ocean perspective. Obviously, the two oceans have affected the history of North America more than South America, where Chile and Peru are Pacific-oriented countries while Brazil is an Atlantic-oriented nation. The Arctic circle is mostly filled with land, with only a sea gap between Scandinavia and Iceland. Certainly Norsemen and Vikings would note this feature. When viewing this map it is easy to see that the location of South America is to the east of North America.
- it becomes obvious that Brazil has no frontage on the Pacific Ocean, is bordered in the west by the Andes, and is strictly an Atlantic Basin country. The equator intersects Brazil at the Amazon and Africa between Nigeria and Angola, with Brazil being closer in nautical miles to Europe and Africa than most of North America. With seventy percent of Brazil's 172.8 million people clustered near the Atlantic coast, it is no wonder that it has been more influenced by Europe (e.g., the national language is Portuguese) and Africa (a multiracial population in which African influences dominate music and religion) than North America. Again, the bulk of African slaves imported into the New World in the eighteenth century went to Brazil, a feature of the relative closeness of the equatorial region of Brazil to a similar climatic zone in Angola and West Africa.
- The current sevenfold categorization of the earth into the continents (that is, continuous, discrete masses of land) of Asia, Europe, Africa, North America, South America, Oceania (Australia and New Zealand), and Antarctica, is a recent convention beginning with the threefold system of the Ancient Greeks and modified over time into today's system. The problem with this kind of classification is that most people consider "continents" to be "real" geographical realities "discovered" through scientific inquiry, instead of what they are—the product of creative imagination and metageography. Continents not only supposedly reflect physical reality, but natural and human features as well . In the field of geology, tectonic plates do not respect the geographer's continental system, with Europe and Asia sharing the same plate for more than thirty-five million years, and India being tectonically linked, not to Asia, but to distant Australia! While it is ridiculous to conceive of Europe as a continent and India a subcontinent, the continental status of Europe (which shares a land mass with Asia), serves to reassure Europeans that their sense of western superiority and false dichotomies (Europe equals West; Asia equals East) will go unchallenged.