Map Work Flashcards
Well drawn map should always have the following features:
- A north arrow
- A scale
- Symbols with a key
- Be drawn from a Birds Eye view
- Title or Latitude/longitude
First world maps began to appear until
Early 16th century
Leading cartographer of the mid 16th century
Mercator from Belgium: developed mapping projection based on mathematics
Mercator published a map of the world in
1569
What’s necessary for creating maps
Map projections
All map projections…
Distort the surface in some fashion
Different map projections exist in order to…
Preserve some properties of the sphere-like body at the expense of other properties. Some distortions are acceptable and others are not
Mercator projection
Cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in 1569. It became the standard map projection for nautical purposes.
Advantages of Mercator projection:
- Uniquely suited to marine navigation
- Courses and bearings are measured using wind roses or protractors
- Corresponding directions are easily transferred from point to point on the map with the help of a parallel ruler or a pair of navigational protractor triangles
Disadvantages of Mercator projection:
- Distorts the size of objects as latitude increases from Equator to poles where scale becomes infinite: Greenland & Antarctica appear much larger relative to land masses near the equator than they actually are
Van der Griten projection
Places the entire Earth into a circle, though the polar regions are subject to extreme distortion
Advantages of van der Griten projection:
It was made famous when the National Geographic Society adopted it as their reference map of the world from 1922 until 1988.
Disadvantages of van der Griten projection:
Polar regions are subject to extreme distortion, it is an arbitrary geometric construction on the plane.
Gall-Peters projection
Named after James Gall and Arno Peters, is an equal-area map projection.
Advantages of Gall-Peters projection:
Areas of equal size on the globe are also equally sized on the map.
Disadvantages of Gall-Peters projection:
Shows extreme distortion in the polar regions, as any cylindrical projection must, and its distortion along the equator is considerable.
3 ways of illustrating scale on map
- Statement or word scale (simple statement)
- Representative fraction [RF] or ratio scale
- A line or linear scale (a line drawn in the margin or at the base of the map from which measurements can be taken).
3 types of symbols
- Point symbols – buildings, dipping tanks, trigonometrical beacons
- Line symbols – railways, roads, power lines, telephone lines,river
- Area symbols – cultivation, orchards & vineyards, pans
6 colour groups for symbols
- Brown: land or earth features = contours, eroded areas, sand areas & dunes
- Light blue: water features = coastlines, dams, lakes, marshes, swamps, rivers, reservoirs. National freeways are shown in dark blue.
- Green: vegetation features = cultivated fields, golf courses, recreational fields, nature & game reserves. White indicates natural vegetation.
- Black: construction features = roads, tracks, railways, buildings, bridges, cemeteries
- Grey: construction features = built-up areas, cadastral information.
- Red: construction features = national, arterial & main roads, lighthouses & marine lights.
- Pink: international boundaries.
- Purple - indicates man-made features that are in the process or have just been constructed and so are new to the map.
5 elements
- Relief: contours, spot heights, trigonometrical beacons
- Water: lakes, rivers, waterholes, reservoirs
- Vegetation: cultivation, orchards & vineyards, forests, plantations, woodland
- Man made: communication lines, settlement
- Political: boundaries
Grid reference:
Locates a point on the Earth in terms of latitude and longitude. Latitude is always written first.
How is height shown on orthophoto and topographic maps
- Contour lines: black lines on photograph, brown on map
- Trig beacons: black triangles on highest points on the map; no. to the right = reference number, no. below = height above sea level
- Bench marks: arrow with the height above sea level
- Spot heights: dots with height above sea level
